Does your USB-C cable matter?
Yes, above 60W. Most USB-C cables carry up to 3A; laptops that charge at 100W or 140W need a cable rated for it.
A charger can only deliver what the cable allows. For phones it rarely matters. For laptops it often does.
The three cable power ratings
| Cable rating | Max current | Max power |
|---|---|---|
| Standard USB-C | 3A | 60W (20V × 3A) |
| 5A, with an “e-marker” chip | 5A | 100W (20V × 5A) |
| 240W (Extended Power Range) | 5A | 240W (48V × 5A) |
Cables rated above 3A contain a small chip, an e-marker, that tells the charger the cable can safely carry more current. Without it, the charger limits itself to 3A.
What this means in practice
- A 65W laptop charger with a standard 3A cable will usually deliver up to 60W, still close to full speed.
- A 100W or 140W charger needs a 5A or 240W cable to reach its rated output.
- Some phone modes need more current than usual. For example, Samsung sells its 45W adapter with a 5A cable.
Data speed is a separate rating
A cable’s data speed (USB 2.0, 10Gbps, 40Gbps…) is independent of its power rating. A cheap charging cable can carry 100W but only USB 2.0 data, and a fast data cable might be limited to 60W. Check the packaging for both.
Wattson’s take: If your laptop charges more slowly than expected, try a cable labelled 100W or 240W before blaming the charger.