Guide · 5 min read
What wattage do I need?
One rule covers everything: find your device's maximum charging input, buy that wattage or the next class up. Extra watts sit unused; missing watts cost you speed. Here's the map.
Device-to-wattage map
| Device | Max input | Buy this class |
|---|---|---|
| AirPods, watches, e-readers | 5–10W | Any — share your phone's |
| iPhone 12–16 | 20–27W | 20W–30W |
| iPhone 17 series | up to 60W burst | 40W Dynamic or 60W+ |
| Galaxy S25/S24 (base) | 25W | 25W PPS |
| Galaxy S Ultra / S+ | 45W | 45W PPS |
| Google Pixel 9/10 | 27–37W | 30–45W PPS |
| iPad / iPad Air | 20–30W | 30W |
| iPad Pro (M4) | ~40W | 45–65W |
| Nintendo Switch / Switch 2 | 18W / 45W | 45W (docks need OEM-spec) |
| Steam Deck / ROG Ally | 45W / 65W | 45–65W |
| MacBook Air | 70W (fast) | 35–70W |
| MacBook Pro 14″ / 16″ | 96W / 140W | 96–100W / 140W |
| Windows ultrabooks | 45–65W | 65W |
The three sizing rules
Round up, never down. A device on an oversized adapter draws exactly its maximum and no more — the negotiation is device-controlled (how PD works). A device on an undersized adapter charges slowly or, under heavy use, loses charge while plugged in.
Multi-port math is additive. Sum the simultaneous draws and add ~20%: laptop (45W) + phone (25W) needs an 85W+ budget, i.e. a 100W multi-port — not a "65W dual" that splits into 45+20 exactly with zero margin.
Above 60W, the cable is part of the spec. 5A e-marked for 61–100W; EPR 240W-rated above that. See the cable guide.
Where the map gets it wrong
Docks and cradles are not devices. A Nintendo Switch draws 18W handheld but its dock negotiates 15V/2.6A — 39W — and refuses to output video on adapters that cannot supply exactly that. The Switch 2 raises the figure to 45W. Buy for the dock, not the console: Switch, Switch 2.
Peak input is not sustained input. An iPhone 17 accepts a 60W burst for the first few minutes and settles near 27W; a Steam Deck asks for 45W while gaming and 30W while idle. Sizing to the peak is correct — it just means the adapter spends most of its life loafing, which is exactly what you want thermally.
Laptops under load are a special case. A 65W ultrabook compiling code can draw more than 65W from the wall and the battery together, so a 65W adapter holds the charge level steady rather than raising it. That is normal, not a fault; step to 100W if you want the battery to climb while working. Full detail at the laptop hub and laptop USB-C charging, with device-specific numbers at chargers by device and ranked picks at best laptop chargers.
FAQ
Is it OK to charge a phone with a laptop charger?
Yes — completely safe on any certified USB-C PD adapter, at any wattage. The phone requests its normal 20–45W profile and the adapter complies.
What wattage do I need for two devices at once?
Add both devices' maximums plus ~20% headroom, then buy a multi-port unit at that total. Two phones: 65W. Phone + ultrabook: 100W.
Does higher wattage charge my phone faster past its limit?
No. Speed is capped by the phone's own maximum input. Past that number, extra adapter watts do nothing — don't pay for them unless you'll add devices.