Wattage · The single-port sweet spot
30W adapters: four rails, and the last brick most people need.
30W is the first wattage that carries a 20V rail, which is what makes it the smallest adapter that can charge a laptop. It is also the exact figure a MacBook Air and an iPad Pro ask for — which is why it is the best single-port buy on the ladder.
The rail ladder
Apple's 30W USB-C Power Adapter (A2164) publishes four fixed profiles, and good third-party 30W GaN units match them:
| Rail | Power | What requests it |
|---|---|---|
| 5V / 3A | 15W | Accessories, hubs, anything without PD |
| 9V / 3A | 27W | Phones at full peak — including Pro iPhones |
| 15V / 2A | 30W | Tablets, handhelds, some docks |
| 20V / 1.5A | 30W | Laptops — the rail 20W bricks do not have |
That 20V line is the whole story. Below 30W an adapter usually stops at 9V or 12V, so a laptop sees no profile it recognises and either refuses to charge or draws a trickle. At 30W it charges properly, if not quickly.
Why 30W is the buy-once wattage
A MacBook Air with Apple silicon ships with a 30W adapter and charges at its normal rate from one. An iPad Pro peaks around 30W. Every iPhone, including the Pro Max, is fully served by the 9V/3A rail with watts to spare. A Steam Deck will run and slowly charge. In practice a single 30W GaN cube covers every device in a typical bag except a Pro-class laptop and a Nintendo Switch dock.
It is also the wattage where GaN stopped being a premium — 30W GaN cubes are now smaller than the old 12W USB-A brick. See 30W GaN chargers for the form-factor comparison.
Picks at this wattage
- 30W
Anker Nano 30W
The size benchmark for this class: full 30W in a folding-plug GaN body barely larger than Apple's old 5W cube.
- Output
- 30W PD
- Port
- 1× USB-C
- Body
- GaN, folding plug
- 30W
Apple 30W USB-C Power Adapter (A2164)
The reference part, with published 5V/9V/15V/20V rails. The right replacement if your MacBook Air brick went missing.
- Output
- 30W, 4 rails
- Port
- 1× USB-C
- Input
- 100–240V
- 30W
UGREEN Nexode 30W-class GaN
Class pick for value. Same rail set in a GaN body, frequently with a slimmer profile than the Apple part at a lower price per watt.
- Output
- 30W PD
- Port
- 1× USB-C
- Body
- GaN
When to size up, when it is overkill
30W is overkill for a phone-only household — 20W does that job for less, and 25W is the Samsung-specific version. Size up to 35W if you want two USB-C ports rather than more total power, or to 45W for a Galaxy Ultra, a Steam Deck or a Switch dock. Above that, 65W is the standardise-on-one-brick answer for a laptop household. The head-to-heads are on 20W vs 30W and 30W vs 45W, and every other device class is mapped in what wattage do I need.
FAQ
Is 30W enough for a MacBook Air?
Yes for normal charging — Apple silicon Airs shipped with a 30W brick. It is not enough for Apple's fast-charge claim, which specifies a 70W adapter on current models.
Does a 30W charger charge an iPhone faster than 20W?
Marginally, and only on Pro models. The 9V/3A rail lets a Pro iPhone reach its mid-20s peak, but a standard iPhone caps near 20W and sees no difference.
What is the difference between a 30W and a 35W adapter?
Total watts barely change; port count does. Apple's 35W part is a dual USB-C adapter that splits roughly in half when both ports are in use, whereas 30W is a single full-power port.