What Is Qi Wireless Charging?
Qi is the leading wireless charging standard used by billions of devices worldwide. Learn how it works, its versions, and whether your device supports it.
Qi (pronounced chee) is the universal wireless charging standard maintained by the Wireless Power Consortium. Over 4 billion Qi-compatible devices have shipped.
What Is Qi Wireless Charging?
Qi (pronounced "chee") is the world's most widely adopted wireless charging standard. Maintained by the Wireless Power Consortium (WPC), it enables power transfer between a charging transmitter (the pad) and a receiver (your device) through electromagnetic induction — with no physical cable connection.
As of 2026, over 4 billion Qi-compatible devices have shipped globally, and virtually every major smartphone manufacturer supports the standard.
How Qi Wireless Charging Works
The science is straightforward. A Qi charging pad contains a transmitter coil. When alternating current flows through it, it generates an oscillating magnetic field. Your phone contains a receiver coil that converts this magnetic field back into electrical current, which the battery management system uses to charge the battery.
The two coils must be close together — typically within 5-8mm — for efficient energy transfer. This is why the phone must be placed directly on or very near the charging pad.
Efficiency
Qi charging is approximately 75-85% efficient. For every 10W supplied to the charger, about 7.5-8.5W reaches the battery. The remaining energy is lost as heat — which is why wireless charging always generates more warmth than wired charging.
Qi Versions
Original Qi (2008-2022)
The original Qi standard evolved from 5W baseline charging to support up to 15W for certified devices. Different devices and chargers negotiate the maximum supported wattage when placed together.
Qi2 (2023-Present)
Qi2 is a significant upgrade that introduced:
- Magnetic Alignment System (MAS): A ring of magnets identical to Apple MagSafe ensures precise coil-to-coil alignment every time, maximising efficiency and enabling consistent 15W+ delivery.
- Standardised 15W: All Qi2 certified devices and chargers support 15W, ending the previous fragmentation where 15W often required specific brand pairings.
- Improved Efficiency: Better coil design and power regulation reduce heat generation.
- Backward Compatibility: Qi2 chargers work with all existing Qi devices at Qi speeds.
Pros and Cons of Qi Wireless Charging
Pros
- Universal compatibility: One charger for all Qi devices (phones, earbuds, watches, tablets)
- Convenience: No fumbling with cables; just place and charge
- Reduced port wear: Fewer USB-C insertions extend connector life
- Clean desk: Eliminates cable clutter
- Safety: Comprehensive protection built into the standard
Cons
- Slower than wired: Even 15W wireless is slower than 25W+ wired charging
- Less efficient: 15-25% energy loss vs 3-8% for wired charging
- Alignment required: Phone must stay on the pad; does not charge while in pocket
- Higher upfront cost: Quality wireless chargers cost more than USB cables
- Heat: More heat generated than wired charging
Safety Notes
Qi charging uses electromagnetic induction operating at 100-200 kHz — a frequency range that is well below any threshold for biological harm. The power levels involved (5-15W) are similar to those in phone calls and Wi-Fi connections, both of which have extensive safety records.
Qi-certified products must pass tests for:
- Thermal safety
- Foreign object detection
- Overcharge and overvoltage protection
- Electromagnetic compatibility
Is Your Device Qi Compatible?
Use the Compatibility Checker to look up your specific device, or check the manufacturer spec sheet for Wireless Charging or Qi listed under connectivity specifications.