Wattage · The old iPad brick
12W adapters: the fastest a USB-A port ever got.
Apple's 12W USB Power Adapter (A1401) delivers 5.2V at 2.4A — 12.5W on paper, sold as 12W. It is the ceiling of the USB-A era, and if you still have one, it is a perfectly good accessory charger rather than e-waste.
Why the number is 12, not 12.5
5.2V × 2.4A = 12.48W. Apple rounded down; third-party clones quote either figure. The 5.2V is deliberate — the extra 0.2V compensates for the voltage lost in a Lightning or micro-USB cable so the device still sees a clean 5V.
The 2.4A part is not a USB standard. Plain USB-A Battery Charging 1.2 tops out at 1.5A (7.5W); to go beyond it Apple puts a resistor divider on the D+/D− data pins that tells an Apple device "2.4A is available here". Samsung, Sony and Qualcomm each used different codes for the same job, which is why an old Android phone sometimes drew only 5W from an Apple 12W brick. Universal negotiation arrived only with USB-C Power Delivery.
What shipped with — or is capped by — 12W
| Device | Relationship to 12W |
|---|---|
| iPad Air, iPad mini, iPad 5th–9th gen | Shipped in the box with the A1401 |
| iPhone 6 through iPhone 11 | Charges at full USB-A speed, no fast-charge trigger |
| iPhone 15/16/17 | Accepts ~12W; expect roughly double the time to 50% versus 20W PD |
| AirPods, Apple Watch puck, Kindle | Already at their own ceiling — 12W changes nothing |
| iPad Pro 11″/13″ | Wants ~30W; 12W barely keeps pace during use |
| Nintendo Switch | Not supported — the console needs 39W at 15V |
Apple's own 12W USB adapter page has the full model history, and iPad fast charging covers what changed when iPads moved to USB-C.
Picks at this wattage
- 12W
Apple 12W USB Power Adapter (A1401)
The original. Worth buying only as an exact replacement for a lost iPad-era brick; anything newer should be USB-C.
- Output
- 5.2V/2.4A
- Port
- 1× USB-A
- Input
- 100–240V
- 2-port
12W-class dual USB-A charger
Class pick for two legacy devices. Look for 2.4A per port and a total rating of 24W if you want both sockets at full speed simultaneously.
- Output
- 5V/2.4A per port
- Ports
- 2× USB-A
- Check
- Total vs per-port
- Car
12W-class USB-A car adapter
Same rail, 12V socket. The sane replacement for a car charger that has stopped holding a phone steady on navigation duty.
- Output
- 5V/2.4A
- Port
- 1× USB-A
- Input
- 12–24V DC
When to size up
Size up whenever a device supports Power Delivery, which means every iPhone since the 8, every iPad since 2018, and effectively all of Android. 18W is the first PD step and doubles usable speed by moving to a 9V rail; 20W is the current phone standard and costs about the same. Step down to 10W or 5W only for accessories. If you are replacing a brick that vanished, the replacement guide matches old adapters to current parts, and the USB-A adapter guide explains why 12W is the end of that road.
FAQ
Can I charge an iPad with a 12W adapter?
Yes — every iPad accepts it, and iPads through the 9th generation shipped with exactly this brick. Newer USB-C iPads will charge, just well below the roughly 30W they can take.
Is 12W enough for an iPhone?
It works and it is safe, but it is not fast charging. Fast charging requires a 9V or higher rail delivered over USB-C PD, which a 12W USB-A brick does not have.
Why does my 12W charger say 5.2V?
The extra 0.2V is headroom for cable losses, so the device still receives close to 5V under a 2.4A load. It is a design choice, not a fault or an out-of-spec output.