Short answer: a laptop that supports USB-C charging will accept power from a USB Power Delivery charger, but how well it charges depends on four things. The first is watts: match or beat the laptop's own adapter for normal speed. The second is the port, because not every USB-C port takes power in. The third is the cable, since anything above 60 W needs an e-marked cable. The fourth is anything in between: docks and hubs keep some power for themselves. A smaller charger usually charges more slowly, may only keep up while the laptop sleeps, and on some laptops will not charge at all.
Our chargers-and-cables guide covers watts and PD in general. This guide is about laptops specifically.
Step 1: find your laptop's number
The easiest reference is the wattage printed on the adapter that came with the laptop, or the maker's recommendation. Apple, for example, recommends adapters by model (as listed in November 2026): from 30 W (13-inch only) up to 70 W for MacBook Air models from 2022 on, 67 W to 96 W for the 14-inch MacBook Pro, and 140 W for the 16-inch. Microsoft lists the Surface Pro 9 at 60 W (15 volts at 4 amps) and the Surface Pro 10 for Business at 39 W minimum and 45 W recommended.
On a Mac you can see what a charger is actually delivering: hold the Option key, choose Apple menu, then System Information, then Power, and read the wattage under AC Charger Information.
What a smaller charger does
| Charger compared with the laptop's own adapter | What usually happens (varies by model) | What the makers say |
|---|---|---|
| Same wattage or higher | Normal charging; the laptop draws only what it needs | Apple: any USB PD adapter or display works, higher or lower wattage |
| Somewhat lower |