2026-11-02
TTBy Tonetron Engineering Team · Dongguan Taitron Electronic Limited
How do I tell a 3 A USB-C cable from a 5 A one?
By the E-Marker, not by thickness. No E-Marker means the link is limited to 3 A.
Answer: the E-Marker declares the current capability. A cable without an E-Marker is limited to 3 A by the spec, however thick it looks.
| E-Marker | Max current |
|---|
| Absent | 3 A |
| Present, declares 3 A | 3 A |
| Present, declares 5 A | 5 A |
Thickness alone proves nothing: a thick cable with a 3 A E-Marker still delivers 3 A.
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Frequently asked questions
How can I tell a 5 A USB-C cable from a 3 A one?
Read the E-Marker — without one the link is limited to 3 A regardless of cable thickness.