Compare · Port shape, power ceiling
USB-A vs USB-C: 12 watts against 240.
A USB-A port on a charger has a hard ceiling. Without Power Delivery it supplies 5 volts, which caps a standard port around 12W and a Quick Charge port around 18W. USB-C negotiates voltage and runs to 240W.
Spec sheet, side by side
| USB-A | USB-C | |
|---|---|---|
| Voltage | 5V fixed (QC ports vary it proprietarily) | 5V, 9V, 15V, 20V, plus 28V/36V/48V on PD 3.1 |
| Typical ceiling | About 12W (5V/2.4A); 18W with Quick Charge | 20W to 240W depending on the adapter |
| Power Delivery | Not supported | Native |
| Connector | One orientation, no e-marker | Reversible, e-marked cables above 3A |
| Data role | Host only | Host or device, plus video and PD over one cable |
| Best-suited devices | Older Kindles, controllers, dash cams, cheap accessories | Every current phone, tablet, handheld and USB-C laptop |
This is why an iPhone plugged into a USB-A port with a USB-A-to-Lightning cable never fast-charges: the 9V rail it needs is a Power Delivery feature, and USB-A cannot offer it. More on the standard at USB standards explained.
Where each one still wins
USB-A wins on legacy cables you already own. A drawer of USB-A cables for a Kindle, a games controller, a dash cam or a bike light is worth one A port on a multi-port charger. Those devices draw 5–10W and will never benefit from more.
USB-C wins on everything current. Every phone sold in the EU is USB-C by law, every MacBook since 2016 charges over it, and the whole Power Delivery ladder from 20W to 240W lives there. It is also the only side that carries the 9V, 15V and 20V rails that make fast charging possible. Detail at USB-A adapters and USB-C power adapters.
Verdict: USB-C, with at most one A port for the drawer
Buy USB-C. On delivered watts it is not a close call — 12W against 20W minimum and 240W maximum — and on protocol correctness USB-A simply cannot participate in Power Delivery at all. The only defensible reason to keep an A port is compatibility with cables you already own for low-draw accessories, and one port covers that. Do not buy an A-only charger new, and do not keep a 5V/2.4A A brick as a phone charger: see 5W vs 20W for what that costs you. If you are choosing because of Quick Charge branding, read USB PD vs Quick Charge; for cable choice, the USB-C cable guide.
- USB-A
Apple 12W USB Power Adapter
The USB-A side at its best: 5V/2.4A for older iPads and legacy accessories.
- Output
- 12W USB-A
- Voltage
- 5V fixed
- PD
- No
- USB-C
Apple 20W USB-C Power Adapter
The USB-C side at the entry point: Power Delivery with the 9V fast-charge rail.
- Output
- 20W USB-C PD
- Rails
- 5V/3A, 9V/2.22A
- Ports
- 1× USB-C
- C+A
Statik 65W GaN 3-Port
The compromise: two USB-C ports for current devices plus one A port for the drawer.
- Output
- 65W total
- Ports
- 2× C, 1× A
- Tech
- GaN
Related: USB-C vs Lightning and the full comparison index.
FAQ
Can a USB-A port fast-charge an iPhone?
No. iPhone fast charging requires the 9V Power Delivery rail, which only exists over USB-C. A USB-A port will charge the phone at roughly 5 to 12W.
Are USB-A ports worth having on a new charger in 2026?
One, at most, for legacy cables. Every device you buy now charges faster and more predictably over USB-C.
Does a USB-A to USB-C cable enable Power Delivery?
No. The A end determines the rules, so the link stays at 5V. Power Delivery requires USB-C on both ends of the connection.