Power markings answer one question
USB-IF’s current certified C-to-C cable power logos use 60 W or 240 W. More than 60 W requires a 5 A electronically marked cable. A legacy 100 W / 5 A claim can still describe an older compliant product, but it is not the current certified new-cable power logo.
Data labels should say the rate
Prefer explicit performance language—USB 5Gbps, 10Gbps, 20Gbps, 40Gbps, or 80Gbps—over generation names. USB 2.0 charge-first cables remain common and may be sufficient for charging while being unsuitable for fast storage or a full-featured display path.
| Claim | What it establishes | What it does not establish |
|---|---|---|
| 240 W | Power class, when genuine and applicable | High-speed data or video |
| USB 20Gbps | Declared USB data rate | 5 A charging or DisplayPort mode |
| USB4 40Gbps | Declared USB4 link class | Exact host display count or dock behavior |
| Thunderbolt | Certified ecosystem capability for the marked generation | Every monitor mode on every host |
Video is a path, not a cable sticker
A full-featured cable can carry DisplayPort Alt Mode only when the source port emits video and the sink or adapter accepts the intended mode. Purpose-built USB-C-to-DisplayPort or USB-C-to-HDMI cables are directional adapters, not general C-to-C data cables.
Length requires exact-model evidence
Signal integrity depends on rate, construction, certification, active electronics, and exact length. That is why Cable Check Lab does not offer a universal cable-length calculator: public standards do not turn one length number into a safe compatibility verdict.
Select requirementsDecode a claimCheck the data pathUSB-IF cable page