USB-C Cable Types: Data, Power and Video

A USB-C cable is not a single product. The connector is the same, but the cable inside may carry only USB 2.0 data, or it may carry 80 Gbps, 240 W of power and a DisplayPort signal. The plug tells you nothing about the wire. This page explains what varies inside a USB-C cable, how to read the labels, and how to pick the right one for charging, data or a monitor.

The connector is not the cable

USB-C is a 24-pin reversible connector, specified in 2014. It says nothing about speed or power. A USB-C cable may be a USB 2.0 cable (480 Mbps) or carry 10, 20, 40 or 80 Gbps. It may be rated for 3 A or 5 A, or for no data at all beyond charging.

When you buy a cable, you are buying three separate capabilities:

• Data speed: how fast it moves files or drives a display.
• Power: how much current it can carry safely.
• Video: whether it carries DisplayPort or Thunderbolt signals.

A cable may have one, two or all three. A charging cable often has only power and USB 2.0 data. A monitor cable needs high-speed data and video. A Thunderbolt cable needs everything.

USB-C data vs charging cable

The most common confusion is between a cable that only charges and a cable that also moves data quickly.

A USB 2.0 USB-C cable has only the USB 2.0 pair wired for data. It can charge at up to 60 W (3 A at 20 V) and may carry video if it is a full-featured cable, but its data speed is 480 Mbps. Many cables sold for phone charging are this type.

A USB 5Gbps, 10Gbps or 20Gbps cable has the extra high-speed pairs. These are the cables you need for external SSDs, docks and monitors. The speed is printed on the packaging, but not always on the cable.

USB-IF now labels products by speed: USB 5Gbps, USB 10Gbps, USB 20Gbps, USB 40Gbps, USB 80Gbps. If a cable has no speed marking, assume it is USB 2.0 unless the maker states otherwise. For a full breakdown of how the old names map to the new ones, see USB 3.0, 3.1, 3.2 and USB4: speeds and names decoded.

What the specification allows for length

USB-C cable lengths are limited by the standard, not by the maker:

Longer cables exist, but they are active or optical, with electronics built into the plugs. A passive cable longer than the table above may work at a lower speed or not at all.

Power: 60 W, 100 W and 240 W

Every USB-C to USB-C cable must carry 3 A, which is 60 W at 20 V. That is the baseline. If you need more than 60 W, the cable must have an e-marker chip.

An e-marker is a small chip in the cable plug that tells the charger and device what the cable can handle. Without it, the devices default to 3 A. With it, the cable can be rated for 5 A (100 W) or, under USB Power Delivery 3.1 Extended Power Range, 240 W at 48 V.

A 100 W cable has an e-marker rated for 5 A. A 240 W cable has an e-marker rated for 5 A and 48 V. If you use a 60 W cable with a 100 W charger and laptop, the laptop will charge at 60 W or less. The cable is the bottleneck.

For a detailed explanation of the wattage labels and how to choose, see USB-C charging: 60 W, 100 W and 240 W cables explained.

USB-C cable for a monitor

Driving a monitor over USB-C uses DisplayPort Alt Mode. The cable must carry the video signal, which means it needs the high-speed pairs and often a specific orientation. Not every USB-C cable does this.

A USB 2.0 charging cable will not drive a monitor. A USB 5Gbps or 10Gbps data cable may or may not support video, depending on how it is wired. The safest choice is a cable marked for USB4, Thunderbolt 3, 4 or 5, or one explicitly sold as a USB-C video cable.

Thunderbolt 4 and 5 cables also work as USB-C cables for data and charging. Thunderbolt 4 supports two 4K displays or one 8K, and up to 100 W charging. Thunderbolt 5 supports 80 Gbps both ways, up to 120 Gbps in one direction for displays, and up to 240 W charging. For the differences between Thunderbolt and USB4, see Thunderbolt 3, 4 and 5 vs USB4.

If you are connecting a monitor that uses HDMI or DisplayPort, a simple USB-C to HDMI or USB-C to DisplayPort cable is often the easiest. These cables have the converter built into the plug and are directional: the USB-C end goes to the computer.

How to read the labels and markings

USB-C cables are rarely marked with their full capabilities. Here is what to look for:

• Speed: USB 5Gbps, 10Gbps, 20Gbps, 40Gbps, 80Gbps. If absent, assume USB 2.0.
• Power: 60 W, 100 W, 240 W, or 3 A, 5 A. If absent, assume 60 W.
• Video: DisplayPort Alt Mode, Thunderbolt, or a specific video standard. If absent, assume no video.
• Certification: Thunderbolt cables have a lightning bolt logo. USB4 cables may have a USB4 logo. These are not guarantees of every feature, but they are a good start.

A cable that says only “USB-C” is a basic cable. It will charge a phone and move data at USB 2.0 speed. It will not drive a monitor or charge a laptop at full speed.

What goes wrong

• Using a charging cable for a dock or monitor. The dock may not work at all, or the monitor may not light up. The cable lacks the high-speed pairs.
• Using a 60 W cable with a 100 W laptop. The laptop charges slowly or not at all under load. The e-marker limits the current to 3 A.
• Assuming a USB-C cable carries video. Many do not. Check for DisplayPort Alt Mode or Thunderbolt.
• Mating an active cable backwards. Active and optical USB-C cables are directional. The source end must go to the computer or charger.
• Using a passive cable that is too long. A 3 m passive USB 10Gbps cable will not meet the standard and may drop to USB 2.0 speed or fail.
• Confusing USB-C with Thunderbolt. Thunderbolt 3, 4 and 5 use the USB-C connector, but not every USB-C port is Thunderbolt. A Thunderbolt cable works in a USB-C port, but a USB-C cable may not work in a Thunderbolt dock at full speed.

Choosing the right cable

Match the cable to the job:

• Phone charging: a USB 2.0 USB-C cable with a 60 W rating is enough for most phones. If your phone supports fast charging above 60 W, get a 100 W cable.
• Laptop charging: check the laptop’s power requirement. If it is above 60 W, get a 100 W or 240 W cable with an e-marker.
• External SSD: get a USB 10Gbps or 20Gbps cable, and keep it short (1 m or less for 10Gbps).
• Monitor: get a USB4 or Thunderbolt cable, or a USB-C to HDMI/DisplayPort cable. Make sure it supports the resolution and refresh rate you need.
• Dock: use the cable that came with the dock, or a Thunderbolt/USB4 cable rated for the dock’s speed and power.

When in doubt, a Thunderbolt 4 or USB4 cable will handle almost everything, but it costs more. For simple charging, a basic USB 2.0 cable is fine.

The bottom line

USB-C is a connector, not a cable specification. The cable inside determines speed, power and video support. Read the labels, check for an e-marker if you need more than 60 W, and choose a cable rated for the speed and features you need. A charging cable will not drive a monitor, and a 60 W cable will not charge a 100 W laptop at full speed.