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, announced in 2023 and deployed in 2024, 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. Qi2.1, published in 2025, extends MPP to higher powers. The three profiles coexist within the same Qi v2.1 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 87-205 kHz power-transfer magnetic field. 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?

Qi operates in the 87-205 kHz band, which is not allocated to a radio service per the ITU Radio Regulations. The system is therefore regulated as an Industrial, Scientific and Medical (ISM) inductive device, not as a radio transmitter. The applicable regimes are FCC Part 18 in the United States, EN 55014 for household EMC and EN 300 330 or EN 303 417 for inductive short-range devices in the European Union. The CE pathway uses the EMC Directive and possibly the RED for any complementary radio (BLE pairing, NFC), but not for the power-transfer link itself. See [EMC immunity tests](/en/guides/iec-61000-4-3-radiated-rf-immunity/) for the immunity counterpart.

What human-exposure tests apply to a Qi pad?

At 87-205 kHz, the dominant exposure quantity is the induced electric field, not the SAR used at GHz frequencies. ICNIRP reference levels for the general public (2010 guidelines) fix the basic restriction at 87 mV/m for induced electric field, with a magnetic field reference level around 27 microtesla in the 3 kHz-10 MHz range, derived to ensure no nerve stimulation. 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?

Qi2 introduces an optional Authenticated Key Exchange (AKE) between the transmitter and the receiver, anchored to the WPC Root CA. Each compliant device carries an X.509 certificate chain signed by the WPC. Before the transmitter authorises an operating power above 5 W, it requests the receiver certificate and validates the chain. The aim is to prevent a counterfeit transmitter from delivering 15 W to a receiver not designed for that power, and to prevent a counterfeit receiver from requesting prohibited power profiles. Authentication is optional in Qi v2.1.0 but is becoming a precondition for access to MPP at maximum power on certain ecosystems.

Qi, Qi2 wireless charging certification (WPC)

Author Hugues Orgitello Last updated 27 May 2026 ~12 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 v2.1 in 2025 which extends MPP to higher powers and consolidates authentication. This guide presents the institutional frame, the Qi v2.1 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 December 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 v2.1 specification family

The Qi v2.1 specification, published in 2025, consolidates the documents previously distributed across Qi 1.3 and Qi2. 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 Qi v2.1
Extended Power Profile	EPP	up to 15 W	Free or multi-coil, with FOD	Qi 1.2.x, kept in Qi v2.1
Magnetic Power Profile	MPP	up to 15 W (Qi2), higher in 2.1	Magnet array imposing position	Qi2 (2023), extended Qi 2.1

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, depending on profile and coil load. 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 Qi v2.1
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 Qi v2.1.

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

Qi power transfer is not a radio service, but it 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	EMC Directive, possibly RED for an embedded radio	EN 300 330 or EN 303 417	Short-range inductive system specification
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

At 87-205 kHz, the dominant biological mechanism is nerve stimulation by induced electric field, not the SAR thermal effect that dominates at GHz frequencies. The applicable reference levels come from ICNIRP 2010 (1 Hz to 100 kHz) and ICNIRP 1998 (100 kHz to 300 GHz), interpolated at the Qi operating frequency.

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 then 2020 (above 100 kHz)	Basic restriction in induced E field

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 of the standard sets the limits per surface category (metal, plastic, glass) and per accessibility duration. A wireless charging pad in normal operation is treated as a constantly-touchable surface, with a strict limit (typically 48 degrees C on metal, 60 degrees C on plastic).

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 v2.1 ships with an optional Authenticated Key Exchange (AKE) anchored at the WPC Root CA. Each compliant device carries an X.509 certificate chain signed by the WPC, downloaded during certification and securely stored in the controller.

Operating principle

The receiver requests a power profile higher than 5 W from the transmitter.
The transmitter requests the receiver certificate chain via the load-modulation channel.
The receiver transmits its certificate chain, signed by an intermediate WPC CA and ultimately by the WPC Root CA.
The transmitter validates the chain against its local copy of the WPC Root certificate.
If validation succeeds, the transmitter authorises the requested power. Otherwise it limits the operating point to 5 W (BPP) or refuses charging.

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 is provisioned in the receiver during production, in a secure element or in the controller's protected memory.

Practical implications

Production line provisioning: each receiver receives a unique certificate, signed by the WPC during the certification process or by a delegated CA. Provisioning is a critical step that must be designed 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 Qi v2.1 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 ignored at 87-205 kHz	Fundamental and second-harmonic radiated emissions out of limits, late discovery in 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
Receiver 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/
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/72082