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01Same plug, different wires
USB-C is the shape of the plug, not a promise about what's inside. The cable types are explained by two separate ratings: power, in watts, and data speed, in megabits or gigabits per second.
A cheap USB-C cable and a $40 Thunderbolt cable both fit every USB-C port. The difference is in the wires and chips inside. Power depends on how thick the power wires are and whether the cable has an e-marker chip to tell the charger it can handle more current. Data speed depends on how many high-speed wire pairs it has and how well they're shielded. A cable can be excellent at one and basic at the other: plenty of 240W charging cables only move data at USB 2.0 speed.
There's also the other end to think about. A USB-C to USB-C cable can use every feature above. A USB-A to USB-C cable can't carry USB Power Delivery, so it charges phones slowly on most chargers and tops out at USB 3 data speeds at best. A USB-C to Lightning cable is its own thing: it fast charges iPhone 8 through 14 with a USB-C PD charger, and moves data at USB 2.0 speed.
02Power ratings: 60W, 100W and 240W
| Rating | Max current | E-marker chip? | What it's for |
|---|---|---|---|
| 60W | 3A at up to 20V | Not required | Every iPhone, Pixel and most Galaxy phones, tablets, small laptops |
| 100W | 5A at up to 20V | Required | Samsung's 45W and 60W modes, most laptops |
| 240W | 5A at up to 48V | Required | Big laptops and gaming laptops using USB PD 3.1 Extended Power Range |
A higher-rated cable is never dangerous for a phone. The phone and charger negotiate the power, and the cable only sets a ceiling. So a 240W cable charges an iPhone exactly as fast as a 60W one. The reverse matters, though: a 60W cable on a 45W Galaxy charger will hold the phone to its slower 25W mode because 45W needs 5A. The e-marker explainer covers that chip, and what is USB Power Delivery explains the negotiation.
Length doesn't change a cable's power rating; a 2 m 60W cable carries 60W just like a 1 m one. Length matters much more for data, which is why the fastest cables are short. More on that in does cable length affect charging speed.
03Data speeds, from USB 2.0 to Thunderbolt 5
| Name on the box | Top speed | Typical use |
|---|---|---|
| USB 2.0 | 480 Mbps | Charging cables, CarPlay, Android Auto, light syncing |
| USB 5Gbps (USB 3.2 Gen 1) | 5 Gbps | External drives |
| USB 10Gbps (USB 3.2 Gen 2) | 10 Gbps | Fast phone backups, SSDs |
| USB 20Gbps (USB 3.2 Gen 2x2) | 20 Gbps | Fast SSDs, on supported PCs |
| USB 40Gbps (USB4) | 40 Gbps | Docks, monitors, external SSDs |
| Thunderbolt 4 | 40 Gbps | Docks and multiple monitors on Thunderbolt laptops |
| USB 80Gbps (USB4 v2) / Thunderbolt 5 | 80 Gbps | High-end docks, external GPUs |
Most phones don't come close to the top of this table. Standard iPhones and many Android phones transfer data at USB 2.0 speed. The iPhone 15 Pro, 16 Pro and 17 Pro models support USB 3 at up to 10 Gbps, but only with a cable that's rated for it, and the cable in the box isn't. If you move big 4K video files off your phone, that's when a 10Gbps cable pays off. For the rest of us, data speed barely matters.
04Reading the label on the box
USB-IF, the group that runs the USB standards, simplified its logos so certified cables show two things on the packaging: a data speed and a wattage. A box that reads "USB 40Gbps" and "240W" tells you everything. Uncertified cables use all sorts of terms, so here's how to decode the common ones:
- "60W" or "3A"
- Standard power. Fine for every phone
- "100W", "240W" or "5A"
- E-marked cable for laptops and Samsung Super Fast Charging 2.0
- "Fast charging" with no number
- Tells you nothing. Assume 60W at most
- "Data sync"
- Usually USB 2.0 (480 Mbps)
- "USB 3.1" / "USB 3.2" alone
- Could be 5, 10 or 20 Gbps. Look for the Gbps figure
- "Supports video" or "4K"
- Needs DisplayPort Alt Mode support, which USB 2.0 cables lack
- Thunderbolt lightning-bolt logo
- Intel-certified Thunderbolt cable; also works as a USB-C cable
Once you own a few, they become impossible to tell apart. A colored band or a bit of tape on the 100W and 10Gbps ones saves a lot of guessing at the desk.
05Which USB-C cable do you need?
60W USB 2.0
- Fast charges every iPhone and Pixel
- Cheapest and most flexible
- Fine for CarPlay and Android Auto
100W or 240W
- 5A, e-marked
- One cable for every device you own
- Usually still USB 2.0 data
10Gbps to 40Gbps
- Fast backups from Pro iPhones
- Needed for video out and docks
- Shorter and stiffer
Comparing the top two tiers? USB4 vs Thunderbolt 4 cables covers when it makes a difference. And if a cable has stopped charging altogether, start with USB-C cable not charging.
Ratings are in the product names, so you can match them to the table above.
Questions people ask
Are all USB-C cables the same?
No. They share a plug shape, but power ratings run from 60W to 240W and data speeds from 480 Mbps to 80 Gbps. Some also support video output and some don't. Check the wattage and Gbps figures on the packaging.
Can I use a 240W USB-C cable to charge my phone?
Yes. The cable only sets a maximum. Your phone and charger agree on how much power to use, so a 240W cable charges a phone safely at its normal speed.
How can I tell if a USB-C cable supports fast charging?
Almost every USB-C to USB-C cable handles 60W, which covers fast charging on iPhones and Pixels. For Samsung's 45W mode or laptops over 60W, look for 100W, 240W or 5A on the label.
What is the difference between a charging cable and a data cable?
Charge-only cables skip the data wires, so they can't sync, transfer files or run CarPlay. Most USB-C cables carry at least USB 2.0 data. Faster data, like 10Gbps or 40Gbps, needs extra wire pairs that basic cables don't have.
Does a USB4 cable work with a phone?
Yes. USB4 cables are backward compatible with every USB-C device. Your phone simply charges and transfers at its own speed, so you won't see any benefit unless you also use the cable with a laptop, dock or monitor.