Apple 10W USB-A Charger (A1357) on a MacBook Air: Measured
Apple's 10W USB-A iPad brick against a MacBook Air M5: 7.1 W delivered, because the Mac won't speak its protocol and falls back to USB BC 1.2.
The Apple 10W USB power adapter (model A1357) shipped with the early iPads. Tested against a MacBook Air M5 with a low battery, per the methodology.
The numbers
| Rated | 10 W |
| Offered | ~8 W (5 V up to 1.5 A) |
| Negotiated | USB BC 1.2 |
| Live draw | 7.1 W (5 V at 1.43 A) |
Profile menu: one entry - ~8 W (5 V up to 1.5 A). No USB Power Delivery; this predates USB-C entirely.
Why 10 W becomes 7 W
The 10 on the label is real - but it’s Apple’s own number, reached through Apple’s proprietary charging signaling (the 2.1-amp mode that pre-PD iPads used). Modern USB-C Macs don’t implement that legacy signaling, so the two devices meet at the strongest standard they share: USB Battery Charging 1.2 (BC 1.2), whose dedicated-charger mode allows up to 1.5 A at 5 V.
5 V × 1.5 A = 7.5 W. That’s the ceiling, and the measured 7.1 W is that contract minus normal losses.
The notable part isn’t the shortfall - it’s that charging works at all. Delivering 7 W to a laptop is an unusually low-power path for a vendor to bother supporting, and macOS handles it without complaint.
Its sibling, the 12W adapter, lands on exactly the same 7.1 W for the same reason - and the 5W cube is capped by its own hardware instead.
No longer sold
Apple retired this adapter years ago, superseded first by the 12W USB-A model and then by the USB-C line-up entirely. Any you find now are second-hand or old stock.
The modern Apple equivalent for compact charging is the 40W Dynamic Power Adapter (60W Max), which speaks USB-C Power Delivery properly and will charge a MacBook Air several times faster than this brick can.
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