What is the difference between Qi 1.x and Qi2?

Qi 1.x, in deployment since 2010, is the historical Wireless Power Consortium specification structured around two profiles: Baseline Power Profile (BPP) at 5 W and Extended Power Profile (EPP) up to 15 W. Coil alignment relies on the user or on a multi-coil array embedded in the pad. Qi2, launched in April 2023 with specification v2.0, adds a Magnetic Power Profile (MPP) based on the magnet array published by Apple under MagSafe, which physically positions the receiver opposite the transmitter coil. Qi v2.2, published in 2025 under the Qi2 25W brand, raises MPP to 25 W. The three profiles coexist within the same Qi2 specification family and may share a single receiver design.

Is Qi certification mandatory to use the Qi logo?

Yes. The Qi mark is a registered trademark of the Wireless Power Consortium (WPC). Using the logo, the brand name "Qi" or the designation "Qi certified" on a product, its packaging or its documentation requires WPC membership and product certification at a WPC-recognised test lab. Use without certification exposes the manufacturer to a trademark action and to removal of the product from the public WPC product registry. Compatibility tests within the consumer ecosystem (iPhone, Samsung Galaxy, Pixel) rely on this registry, and an uncertified product is rejected by the host device authentication chain when present.

Which labs are recognised by the WPC?

The WPC publishes the list of Authorised Test Laboratories (ATL) on its site. Among the most active labs: Allion (Taiwan, US), UL (US, several locations), TUV Rheinland (Germany and Asia branches), Element Materials Technology (US, UK), MET Labs (US), Bureau Veritas CPS (US, Asia). Each lab covers a portion of the Compliance Test Specifications (CT) and the relevant Interoperability Test Specifications (IT). For a multi-region product, the choice of lab is generally guided by proximity to the engineering team and by ATL capacity to handle the targeted profile (BPP, EPP, MPP).

What is Foreign Object Detection (FOD) and why does it matter?

FOD is the function by which a Qi transmitter detects a metallic foreign object (coin, key, ring, foil) placed in its magnetic field and shuts down power transfer to avoid heating that object. The Qi specification mandates FOD for EPP and MPP, with a power-loss method (the transmitter compares the power supplied with the power acknowledged received by the receiver, and infers the loss attributed to a foreign object) or a Q-factor method (the transmitter measures the quality factor of its primary coil and detects the resonance drop caused by a metallic object). A poorly-calibrated FOD is the leading cause of EPP and MPP certification failures.

Does Qi communication use a separate radio?

No. Qi receiver-to-transmitter communication uses load modulation at about 2 kHz, directly over the power-transfer magnetic field itself. The receiver applies a controlled modulation to its load impedance, the transmitter senses it on its primary current, and the resulting data link carries Control Error Packets and configuration packets. Qi does not require a separate radio channel. Qi2 with authentication uses the same in-band channel, with cryptographic exchanges encoded on top of the existing messages.

Does Qi count as a radio service for FCC and RED?

The two jurisdictions answer differently. Qi power transfer runs at 87-205 kHz for BPP and EPP and at 360 kHz for MPP, none of which is allocated to a radio service by the ITU Radio Regulations, so in the United States the system is regulated as an Industrial, Scientific and Medical (ISM) inductive device under FCC Part 18, not as a radio transmitter. In the European Union the answer runs the other way: EN 303 417 states in its scope that a wireless power transmission system carrying inherent in-band communication is radio equipment, which is exactly what Qi does with its load-modulation and FSK messages. The power-transfer link is therefore assessed under the RED, article 3(2), not under the EMC Directive, and the RED reaches the power link itself, not only a complementary radio such as BLE pairing or NFC. Only one of the two ETSI candidates actually reaches a Qi design, though. EN 303 417 is written for the 19-21 kHz, 59-61 kHz, 79-90 kHz, 100-300 kHz and 6 765-6 795 kHz ranges, so a BPP or EPP link at 87-205 kHz sits inside it only from 100 kHz up, and an MPP link at 360 kHz sits outside every one of them. It is also absent from Annex I of Implementing Decision (EU) 2022/2191, so it is not cited in the Official Journal and confers no presumption of conformity. EN 300 330 spans 9 kHz to 25 MHz, covers both profiles end to end, and is cited. See EMC immunity tests for the immunity counterpart.

What human-exposure tests apply to a Qi pad?

At the Qi operating frequencies, 87-205 kHz for BPP and EPP and 360 kHz for MPP, the dominant exposure quantity is the induced electric field, not the SAR used at GHz frequencies. The ICNIRP 2010 guidelines set the general-public basic restriction on induced electric field across 3 kHz to 10 MHz at 1.35 × 10⁻⁴ times the frequency in hertz, in volts per metre, so it moves with frequency: about 11.7 V/m at 87 kHz, 27.7 V/m at 205 kHz and 48.6 V/m at 360 kHz. The general-public reference levels over that same range, which is what a lab actually measures, are 83 V/m, 21 A/m and 27 microtesla. An MPP transmitter at 360 kHz does not leave the low-frequency document behind: ICNIRP 2010 extends its nervous-system guidance to 10 MHz, and its own reference-level table notes that above 100 kHz the RF reference levels apply in addition. Both documents are in scope at 360 kHz, one for nerve stimulation and one for heating. The FCC RF exposure rules (47 CFR Section 1.1310) apply, with uncontrolled environment limits, as does EU Recommendation 1999/519/EC. Most Qi pads remain compliant by design because the coupling distance is a few millimetres and the field decays rapidly. Lab measurement may still be required for multi-coil pads or higher-power MPP designs.

What does Qi2 authentication add over Qi 1.x?

Qi authentication runs from the charger to the phone, not the other way round. Qi 1.3 and Qi2 require EPP and MPP power transmitters to carry a Product Unit Certificate: an X.509 leaf issued by a Manufacturer CA and chaining to the WPC Root CA (WPCCA1). The power receiver is the relying party: it challenges the transmitter, validates the chain and decides whether to accept more than 5 W. The aim is to stop a counterfeit or uncertified charger from delivering 15 W or 25 W to a phone that has no other way of knowing what it is sitting on. A transmitter that cannot present a valid chain is held at Baseline Power Profile (5 W). Certificates are bought from an approved Manufacturer CA Service Provider and provisioned unit by unit on the production line; they are not an output of the test campaign.

Qi, Qi2 wireless charging certification (WPC)

Author Hugues Orgitello Last updated 30 August 2026 ~14 min read

Guide, Qi wireless charging certification

Wireless charging on consumer electronics is structured around the Qi specification published by the Wireless Power Consortium (WPC), an industry body created in 2008 that today brings together several hundred manufacturers, silicon suppliers, accessory makers and test laboratories. Since the first commercial deployments in 2010, Qi has gone through three major generations: Qi 1.x with Baseline Power Profile (BPP, 5 W) and Extended Power Profile (EPP, up to 15 W), then Qi2 introduced in 2023 with the Magnetic Power Profile (MPP) based on the alignment magnet array originally published by Apple under MagSafe, and finally Qi v2.2 in 2025, under the Qi2 25W brand, which raises MPP to 25 W. This guide presents the institutional frame, the Qi specification family, the certification process by a WPC Authorised Test Laboratory, the applicable EMC and human-exposure regimes, the thermal and Foreign Object Detection requirements, then the recurring pitfalls observed on transmitter and receiver projects.

Wireless Power Consortium and the Qi mark

The Wireless Power Consortium is a not-for-profit industry association registered in the Netherlands, founded in 2008 by a small group of consumer-electronics manufacturers. Its mandate is the publication and maintenance of the Qi specification, the management of the Qi trademark and the operation of the certification programme. The WPC does not test products itself: it authorises an external network of Authorised Test Laboratories (ATL) that run the Compliance Test Specifications (CT) and the Interoperability Test Specifications (IT).

WPC membership tiers

Tier	Typical scope	Voting rights	Specification access
Regular Member	Component supplier, integrator, accessory maker	Limited	Public specs plus member-only documents
Full Member	Active participant in working groups	Full vote on specification ballots	Drafts, errata, design support documents
Adopter	Manufacturer who only wishes to certify	No vote	Final specifications and CT documents

Membership is a precondition for filing a certification request: a product is registered against a member account. The annual fees and the per-product certification fees are published in the WPC fee schedule, available on the consortium site to members. Per-product fees vary by profile (BPP, EPP, MPP) and by submission status (new product, derivative, re-test after change).

Qi product registry

Each Qi certified product is recorded in the WPC public registry, with a Qi ID, the model name, the supplier, the profile and the maximum certified power. The registry is queried by host devices that implement Qi2 authentication, and by integrators looking to validate the conformity of a component sourced on the market. A product removed from the registry following a non-compliance loses the right to use the Qi mark, even when units are still in distribution.

Qi specification family

The Qi v2 specification was published as v2.0 in April 2023, then v2.1 in September 2024, v2.2 (Qi2 25W) in April 2025 and v2.3 in December 2025, consolidating the documents previously distributed across Qi 1.3 and Qi2. The WPC gives v2.3 as the current version, available to members only. It is structured into four families of normative documents.

Family	Code	Subject
System Description	SD	Functional architecture, profiles, communication, power-control sequences
Test Specifications	T	Reference test methods (test fixtures, instrumentation, calibration)
Compliance Test Specifications	CT	Detailed pass/fail criteria, test patterns, sample reports
Interoperability Test Specifications	IT	Cross-tests of receivers against a transmitter sample pool and vice versa

A certifiable product is described in the SD family, evaluated against the CT family in lab, and validated end-to-end against the IT family on a sample of certified peer products. A single CT campaign does not guarantee certification: an IT failure on a single peer product blocks the issuance of the Qi ID until the root cause is resolved.

Power profiles

Profile	Code	Max power	Coil alignment	Status
Baseline Power Profile	BPP	5 W	Free or multi-coil	Qi 1.x, kept in Qi2
Extended Power Profile	EPP	up to 15 W	Free or multi-coil, with FOD	Qi 1.2.x, kept in Qi2
Magnetic Power Profile	MPP	15 W (Qi2), 25 W (Qi2 25W)	Magnet array imposing position	Qi2 (2023), extended in v2.2 (2025)

The three profiles can coexist in a single device. A modern smartphone receiver typically advertises BPP, EPP and MPP, and negotiates with the transmitter the highest profile common to both endpoints.

Operating frequency and communication

The power-transfer link operates in the 87-205 kHz band for BPP and EPP. The Magnetic Power Profile introduced in Qi v2.0 moved to a 360 kHz operating frequency, so a Qi2 MPP design places its fundamental, and therefore its whole harmonic comb, in a different place from a Qi 1.x design. Receiver-to-transmitter communication uses load modulation at about 2 kHz, encoded as Differential Bi-phase. The transmitter senses load modulation on its primary current and decodes Control Error Packets, Received Power Packets, Configuration Packets and end-of-charge messages. The transmitter has no direct return channel: it adapts its driving frequency, duty cycle or voltage in response to the received messages.

Certification process

The certification process from a finished product to a Qi ID typically runs in eight steps. The order varies marginally per lab but the substance is set by the WPC.

WPC membership. Sign up at the chosen tier, obtain the credentials needed to access the certification portal.
Product specification freeze. Coil reference (inductance, Q-factor, winding), ferrite, capacitor, controller, firmware version, mechanical enclosure. Any later change reopens the process.
Internal pre-tests. Foreign Object Detection calibration, thermal mapping, Q-factor measurement, EMC pre-scan in the 9 kHz-30 MHz band. The aim is to fix obvious failures before paying for the lab.
Lab booking. Pick an Authorised Test Laboratory (Allion, UL, TUV Rheinland, Element, MET, Bureau Veritas CPS, and others) recognised for the targeted profile. Allow several weeks of lead time depending on the period.
Compliance Test campaign (CT). Execution of the CT documents corresponding to the product (CT-PTx for a transmitter, CT-PRx for a receiver), including FOD, thermal, communication, power efficiency, mechanical alignment.
Interoperability Test campaign (IT). Cross-tests against a sample pool of certified products: a transmitter is verified against a set of receivers, a receiver against a set of transmitters. The pool is maintained by the WPC.
Submission to WPC. The CT and IT reports are uploaded to the WPC portal, reviewed by the consortium technical team. Comments and clarification requests are managed by exchange of messages.
Qi ID issuance and registry listing. Once the dossier is accepted, the WPC issues a Qi ID, lists the product in the public registry and authorises use of the Qi mark on packaging and documentation.

For the broader cross-cutting view, see certification timeline and certification costs.

Foreign Object Detection (FOD)

FOD is the central safety function of Qi. Without it, a metallic object placed in the field heats by induction and can reach hazardous temperatures within seconds.

Detection methods

Method	Principle	Status in Qi2
Power-loss accounting	The transmitter compares the power delivered with the power acknowledged received, and infers the loss attributed to a foreign object	Historical method, kept
Q-factor measurement	The transmitter measures the quality factor of its primary coil before and during charging, detects the drop caused by a metallic object	Mandatory complement on EPP and MPP
Resonance shift	The transmitter measures the change of the resonance frequency caused by the foreign object	Optional, used as cross-check
NFC-based detection	The transmitter scans for NFC tags whose response indicates that a chip card or passport is present	Optional, recommended for accessory pads

The combination of power-loss and Q-factor methods is the practical standard on EPP and MPP. A single method is no longer sufficient to pass CT for these profiles in Qi2.

Standard pre-tests

The CT documents prescribe a panel of standardised foreign objects placed on the transmitter, with maximum temperatures verified by thermocouple or thermal camera. The typical panel includes:

EU 1-cent and 50-cent coin (low-cost reference, recurring use case),
US dime and quarter (US market),
keychain ring (steel),
paperclip (small bulk, low coupling, detection limit),
aluminium foil square (low mass, very high coupling),
steel washer (medium mass).

Each object is positioned in turn at the centre of the active coil, with the transmitter running at its nominal power. The temperature reached after a 30-minute exposure must remain below the lab threshold (typically 65-70 degrees C, depending on the CT document version). A passed test is recorded with a photograph and a thermal mapping.

Q-factor, resonance and Qi-specific tests

Beyond the receiver power, the CT campaign characterises several intrinsic parameters of the transmitter or receiver coil.

Parameter	Definition	Typical value
Coil inductance	Primary or secondary inductance at the operating frequency	6-12 microhenry
Quality factor (Q)	Ratio of stored energy to dissipated energy per cycle	80-200
Resonance frequency	Primary frequency of the LC tank	100-150 kHz for BPP, adjusted for MPP
Reference temperature	Coil temperature at full power	depends on profile and time

Q-factor drift between prototype and production is a recurring failure cause. A change of ferrite supplier, an insertion of a metallic part in the enclosure or a layout change on the controller PCB can divide the Q by two, prevent FOD calibration and cause IT failures against certain receivers.

EMC at 87-205 kHz (BPP, EPP) and 360 kHz (MPP)

Qi power transfer is not allocated to a radio service by the ITU Radio Regulations, but in the European Union a wireless power system carrying in-band communication is radio equipment, and the transfer produces harmonics across the 9 kHz-30 MHz band that are measured under several regimes.

Applicable regimes by region

Region	Regulatory regime	Applicable standard	Comment
United States	FCC Part 18 (ISM equipment)	FCC Part 18	Conducted emissions on power supply, radiated emissions per ISM band
European Union	RED article 3(2), power-transfer link included	EN 300 330 (9 kHz to 25 MHz, cited in the Official Journal). EN 303 417 does not cover 360 kHz and is not cited	Short-range inductive system specification; EN 300 330 is the only cited standard that spans both Qi profiles
European Union (household)	EMC Directive	EN 55014	Household appliances and similar (depends on product positioning)
Japan	Radio Law, mandatory MIC notification for some powers	Telec inductive technical conditions	Public auctioning of Qi spectrum management since 2018
Korea	Radio Research Agency, KC marking	KS C 9618 series	Korean alignment on the Qi spec

The first-order EMC pre-scan covers the 9-150 kHz band (LF emissions, very low ambient noise, very sensitive to switching mode), the 150 kHz-30 MHz band (conducted emissions per CISPR 11 or 22), and the 30-300 MHz radiated emissions band where ringing on transient switching can emerge. A radiated pre-scan in an open lab, before the formal EMC campaign, often saves a wasted-lab visit.

Coupling to the surrounding EMC stack

The product does not stop at Qi. A finished consumer product typically includes Bluetooth (host, accessory), Wi-Fi (host) and NFC alongside Qi. Each radio brings its own EMC envelope, with risks of interaction in the harmonics. See Bluetooth SIG qualification and RED tests.

Human exposure and ICNIRP

Across the Qi operating frequencies the dominant biological mechanism is nerve stimulation by induced electric field, not the SAR thermal effect that dominates at GHz frequencies. For BPP and EPP the 87-205 kHz band straddles the 100 kHz boundary between the two ICNIRP guideline documents, so the assessment has to name which side of 100 kHz each measurement point sits on. For MPP at 360 kHz the fundamental sits above 100 kHz, but that does not retire the low-frequency document: ICNIRP 2010 extends its nervous-system guidance to 10 MHz, and its reference-level table states that above 100 kHz the RF reference levels apply in addition. Both are in scope at 360 kHz, the 2010 document for nerve stimulation and the 100 kHz to 300 GHz document for heating.

Region	Regulation	Limit type
EU	Recommendation 1999/519/EC general public, Directive 2013/35/EU workers	ICNIRP 2010 reference levels
United States	FCC 47 CFR Section 1.1310	Maximum Permissible Exposure (MPE), uncontrolled environment
International	ICNIRP 2010 up to 10 MHz for nerve stimulation, ICNIRP 2020 in addition above 100 kHz	Induced E field basic restriction, general public, 1.35 × 10⁻⁴ times the frequency in hertz

In practice, a 5 W BPP pad with the receiver in contact remains compliant by design: the field drops several orders of magnitude within a few centimetres. For a 15 W MPP transmitter, the verification is more rigorous and may require an SAR-style measurement done on a phantom representative of the body part exposed.

Thermal safety and IEC 62368-1

The user-touchable surface of a Qi transmitter or a charging receiver is subject to the temperature limits of IEC 62368-1:2023, Table 38.

Three variables set the limit, and a single number is not transferable between them: the surface material (metal conducts heat into the hand far faster than plastic or glass, so its ceiling is the lowest of the three), the contact duration the design implies, and who is expected to touch it. A wireless charging pad is the demanding case on all three at once, because it is treated as continuously touchable by an ordinary person for the whole charge cycle. Read the values in the standard against your own material and duration rather than carrying a figure across from another product: the same 45 degrees C is compliant on one surface and a failure on another.

What the design actually has to absorb is that the limit applies to the enclosure the user touches, not to the coil, so the thermal path from coil to shell is the variable under your control.

Qi itself adds its own thermal cap, often more restrictive than IEC 62368-1, with measurement at defined points on the transmitter surface (centre coil, peripheral coil for multi-coil pads, immediate vicinity of the controller IC). Failure on a 62368-1 thermal point is the second leading cause of EPP and MPP certification failures, after FOD.

For the battery side of a charging receiver, see IEC 62133 and UN 38.3 on cell safety and transport.

Multi-coil pads and free positioning

A multi-coil pad embeds two, three or more primary coils, distributed across the surface to give the user true free positioning. The transmitter detects which coil best couples to the receiver and activates it. Multi-coil designs face several additional certification challenges:

Crosstalk between coils: a non-active coil can couple to a foreign object placed on it, requiring extension of FOD to all coils, not only the active one.
Selective activation: the activation decision algorithm must be deterministic and validated for the full range of receiver positions, including diagonals and edges.
Q-factor calibration: each coil has its own Q, its own FOD calibration parameters, its own reference temperature.
Increased EMC envelope: the more active coils, the broader the radiated harmonics spectrum, with risks of intermodulation at the operating frequency sums and differences.

Multi-coil designs add a measurable cost to the certification campaign, both in CT and in IT.

Qi2 authentication and the WPC PKI

Qi authenticates the charger, not the phone. Qi 1.3 and Qi2 require EPP and MPP power transmitters to carry a Product Unit Certificate: an X.509 leaf issued by a Manufacturer CA and chaining to the WPC Root CA (WPCCA1). The power receiver is the relying party: it challenges the transmitter and decides whether to accept more than 5 W.

Operating principle

The receiver asks the transmitter for the digests of its certificate chain. Requests travel on the load-modulation (ASK) channel; the transmitter answers on the FSK channel.
The receiver requests whichever certificates it does not already cache: the Product Unit Certificate and the Manufacturer CA certificate above it.
The receiver sends a random challenge; the transmitter signs it with the private key paired to its Product Unit Certificate.
The receiver validates the chain against the WPC Root certificate hash it stores, then verifies the signature over its own challenge.
If any step fails, the receiver holds the negotiation at Baseline Power Profile (5 W) instead of moving to EPP or MPP.

The cryptographic primitives use ECDSA on P-256, with hashing on SHA-256. The exchange must complete in under a few seconds via the 2 kHz channel, which requires care in message encoding. The certificate and its private key are provisioned in the transmitter during production, in a secure element or in the controller's protected memory.

Practical implications

Production line provisioning: certificates are not an output of the test campaign. A transmitter manufacturer signs the Authentication Agreement for a Manufacturer, procures Product Unit Certificates from an approved Manufacturer CA Service Provider (Infineon, NXP, ST, Microchip and others) and tells the WPC licence administrator which MCSP will supply them. The WPC Root CA signs only Manufacturer CA certificates, on a weekly signing cycle. Each unit is then provisioned with a unique certificate on the line, which is a step to design in from the start.
Counterfeits: an uncertified product cannot generate a valid chain. The protection is effective against generic clones, but it does not stop a counterfeiter who would reuse a stolen genuine certificate (revocation and certificate transparency are kept under WPC governance).
Backwards compatibility: a Qi2 transmitter must still charge a Qi 1.x receiver at 5 W, without authentication. Authentication is only required to unlock higher powers.

For the broader IoT cybersecurity context, see EN 303 645 and CRA.

Common pitfalls

Pitfall	Consequence
FOD not calibrated on the production line	Variability of the metallic object detection threshold, intermittent EPP failure
Q-factor drifted by an enclosure metal part	Q below the calibration threshold, FOD impossible, return to design
EMC pre-scan run only over 87-205 kHz on a Qi2 MPP design	Fundamental at 360 kHz and its harmonics never characterised, late discovery in the formal lab
Inverted Qi2 magnet polarity	No magnetic contact, receiver impossible to align with an iPhone MagSafe or other Qi2 transmitter
MagSafe compatibility claimed without Qi2 certification	Trademark infringement risk, possible Apple action, removal from the Apple ecosystem
Transmitter certificate non-unique per unit	Identification confusion, revocation impossible without removing a complete batch
Insufficient thermal headroom on the enclosure	IEC 62368-1 limit reached in EPP, certification refused
Bluetooth or Wi-Fi radio not isolated from the coil	Spurious modulation of the radio signal by the magnetic field, RED failure on the embedded radio

Going further

MFi made for iPhone: Apple's accessory programme, partially aligned with Qi2 for MagSafe
IEC 62133 and UN 38.3: cells and transport, the battery side of a Qi receiver
IEC 61000-4-3 radiated immunity: EMC immunity, the immunity counterpart of Qi emission measurements
Bluetooth SIG qualification: for products combining Qi and Bluetooth
Certification timeline: cross-cutting orders of magnitude per phase
Glossary: definitions of BPP, EPP, MPP, FOD, Q-factor, ATL, AKE, WPC Root CA

Sources & references

Wireless Power Consortium, Qi specification documents , Wireless Power Consortium www.wirelesspowerconsortium.com/knowledge-base/specifications/
WPC public product registry (Qi certified products database) , Wireless Power Consortium www.wirelesspowerconsortium.com/products/
FCC 47 CFR Part 18, Industrial, Scientific, and Medical Equipment , FCC www.ecfr.gov/current/title-47/chapter-I/subchapter-A/part-18
EN 300 330, Short Range Devices in 9 kHz to 25 MHz, inductive loop systems , ETSI www.etsi.org/deliver/etsi_en/300300_300399/300330/
EN 303 417, Wireless power transmission systems in 19-21 kHz, 59-61 kHz, 79-90 kHz, 100-300 kHz, 6 765-6 795 kHz frequency ranges , ETSI www.etsi.org/deliver/etsi_en/303400_303499/303417/
Commission Implementing Decision (EU) 2022/2191, harmonised standards for radio equipment (Annex I) , European Commission eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32022D2191
ICNIRP Guidelines for limiting exposure to time-varying electric and magnetic fields (1 Hz to 100 kHz) , ICNIRP www.icnirp.org/en/publications/article/lf-guidelines-2010.html
IEC 62368-1:2023, Audio/video, information and communication technology equipment, safety requirements , IEC webstore.iec.ch/publication/69308

Frequently asked questions

What is the difference between Qi 1.x and Qi2?: Qi 1.x, in deployment since 2010, is the historical Wireless Power Consortium specification structured around two profiles: Baseline Power Profile (BPP) at 5 W and Extended Power Profile (EPP) up to 15 W. Coil alignment relies on the user or on a multi-coil array embedded in the pad. Qi2, launched in April 2023 with specification v2.0, adds a Magnetic Power Profile (MPP) based on the magnet array published by Apple under MagSafe, which physically positions the receiver opposite the transmitter coil. Qi v2.2, published in 2025 under the Qi2 25W brand, raises MPP to 25 W. The three profiles coexist within the same Qi2 specification family and may share a single receiver design.
Is Qi certification mandatory to use the Qi logo?: Yes. The Qi mark is a registered trademark of the Wireless Power Consortium (WPC). Using the logo, the brand name "Qi" or the designation "Qi certified" on a product, its packaging or its documentation requires WPC membership and product certification at a WPC-recognised test lab. Use without certification exposes the manufacturer to a trademark action and to removal of the product from the public WPC product registry. Compatibility tests within the consumer ecosystem (iPhone, Samsung Galaxy, Pixel) rely on this registry, and an uncertified product is rejected by the host device authentication chain when present.
Which labs are recognised by the WPC?: The WPC publishes the list of Authorised Test Laboratories (ATL) on its site. Among the most active labs: Allion (Taiwan, US), UL (US, several locations), TUV Rheinland (Germany and Asia branches), Element Materials Technology (US, UK), MET Labs (US), Bureau Veritas CPS (US, Asia). Each lab covers a portion of the Compliance Test Specifications (CT) and the relevant Interoperability Test Specifications (IT). For a multi-region product, the choice of lab is generally guided by proximity to the engineering team and by ATL capacity to handle the targeted profile (BPP, EPP, MPP).
What is Foreign Object Detection (FOD) and why does it matter?: FOD is the function by which a Qi transmitter detects a metallic foreign object (coin, key, ring, foil) placed in its magnetic field and shuts down power transfer to avoid heating that object. The Qi specification mandates FOD for EPP and MPP, with a power-loss method (the transmitter compares the power supplied with the power acknowledged received by the receiver, and infers the loss attributed to a foreign object) or a Q-factor method (the transmitter measures the quality factor of its primary coil and detects the resonance drop caused by a metallic object). A poorly-calibrated FOD is the leading cause of EPP and MPP certification failures.
Does Qi communication use a separate radio?: No. Qi receiver-to-transmitter communication uses load modulation at about 2 kHz, directly over the power-transfer magnetic field itself. The receiver applies a controlled modulation to its load impedance, the transmitter senses it on its primary current, and the resulting data link carries Control Error Packets and configuration packets. Qi does not require a separate radio channel. Qi2 with authentication uses the same in-band channel, with cryptographic exchanges encoded on top of the existing messages.
Does Qi count as a radio service for FCC and RED?: The two jurisdictions answer differently. Qi power transfer runs at 87-205 kHz for BPP and EPP and at 360 kHz for MPP, none of which is allocated to a radio service by the ITU Radio Regulations, so in the United States the system is regulated as an Industrial, Scientific and Medical (ISM) inductive device under FCC Part 18, not as a radio transmitter. In the European Union the answer runs the other way: EN 303 417 states in its scope that a wireless power transmission system carrying inherent in-band communication is radio equipment, which is exactly what Qi does with its load-modulation and FSK messages. The power-transfer link is therefore assessed under the RED, article 3(2), not under the EMC Directive, and the RED reaches the power link itself, not only a complementary radio such as BLE pairing or NFC. Only one of the two ETSI candidates actually reaches a Qi design, though. EN 303 417 is written for the 19-21 kHz, 59-61 kHz, 79-90 kHz, 100-300 kHz and 6 765-6 795 kHz ranges, so a BPP or EPP link at 87-205 kHz sits inside it only from 100 kHz up, and an MPP link at 360 kHz sits outside every one of them. It is also absent from Annex I of Implementing Decision (EU) 2022/2191, so it is not cited in the Official Journal and confers no presumption of conformity. EN 300 330 spans 9 kHz to 25 MHz, covers both profiles end to end, and is cited. See EMC immunity tests for the immunity counterpart.
What human-exposure tests apply to a Qi pad?: At the Qi operating frequencies, 87-205 kHz for BPP and EPP and 360 kHz for MPP, the dominant exposure quantity is the induced electric field, not the SAR used at GHz frequencies. The ICNIRP 2010 guidelines set the general-public basic restriction on induced electric field across 3 kHz to 10 MHz at 1.35 × 10⁻⁴ times the frequency in hertz, in volts per metre, so it moves with frequency: about 11.7 V/m at 87 kHz, 27.7 V/m at 205 kHz and 48.6 V/m at 360 kHz. The general-public reference levels over that same range, which is what a lab actually measures, are 83 V/m, 21 A/m and 27 microtesla. An MPP transmitter at 360 kHz does not leave the low-frequency document behind: ICNIRP 2010 extends its nervous-system guidance to 10 MHz, and its own reference-level table notes that above 100 kHz the RF reference levels apply in addition. Both documents are in scope at 360 kHz, one for nerve stimulation and one for heating. The FCC RF exposure rules (47 CFR Section 1.1310) apply, with uncontrolled environment limits, as does EU Recommendation 1999/519/EC. Most Qi pads remain compliant by design because the coupling distance is a few millimetres and the field decays rapidly. Lab measurement may still be required for multi-coil pads or higher-power MPP designs.
What does Qi2 authentication add over Qi 1.x?: Qi authentication runs from the charger to the phone, not the other way round. Qi 1.3 and Qi2 require EPP and MPP power transmitters to carry a Product Unit Certificate: an X.509 leaf issued by a Manufacturer CA and chaining to the WPC Root CA (WPCCA1). The power receiver is the relying party: it challenges the transmitter, validates the chain and decides whether to accept more than 5 W. The aim is to stop a counterfeit or uncertified charger from delivering 15 W or 25 W to a phone that has no other way of knowing what it is sitting on. A transmitter that cannot present a valid chain is held at Baseline Power Profile (5 W). Certificates are bought from an approved Manufacturer CA Service Provider and provisioned unit by unit on the production line; they are not an output of the test campaign.