USB-C connector — specs & standards explained
USB-C is a connector shape, not a speed standard. The oval reversible plug can carry USB 2.0, USB 3.2, USB4, Thunderbolt 3, or Thunderbolt 4 — you cannot tell which from the shape alone. This page explains each standard and how to identify what your port actually supports.
⚠️ The USB-C shape ≠ speed or power
A cheap phone charger cable can use USB-C connectors at both ends but only carry USB 2.0 speeds (480 Mbps) and limited wattage. Always check the cable or device specification, not just the connector shape.
USB-C speed tiers
| Standard | Max speed | Cable requirement |
|---|---|---|
| USB 2.0 via USB-C | 480 Mbps | Any USB-C cable |
| USB 3.2 Gen 1 | 5 Gbps | USB 3.2 Gen 1 cable |
| USB 3.2 Gen 2 | 10 Gbps | USB 3.2 Gen 2 cable |
| USB 3.2 Gen 2×2 | 20 Gbps | USB 3.2 Gen 2×2 cable (USB-C only) |
| USB4 Gen 2×2 | 20 Gbps | USB4 cable |
| USB4 Gen 3×2 | 40 Gbps | USB4 cable (40 Gbps rated) |
| Thunderbolt 3 | 40 Gbps | Thunderbolt 3 cable (passive ≤0.5 m, active >0.5 m) |
| Thunderbolt 4 | 40 Gbps | Thunderbolt 4 cable |
Thunderbolt vs USB4
Both Thunderbolt 4 and USB4 Gen 3×2 use USB-C connectors and top out at 40 Gbps. Key differences:
- Thunderbolt 4 mandates certain features (two 4K displays, PCIe tunnelling) that USB4 makes optional.
- A Thunderbolt 4 cable works in a USB4 port and vice-versa at compatible speeds — the certifications differ, not the connector.
- Look for the lightning-bolt icon next to the port to identify Thunderbolt on laptops and monitors.
USB Power Delivery (USB PD)
| Profile | Max wattage | Typical use |
|---|---|---|
| Standard (USB 2.0) | 2.5 W (5 V / 0.5 A) | Basic charging, data |
| USB BC 1.2 | 7.5 W (5 V / 1.5 A) | Phone charging |
| USB PD 2.0 | 100 W (20 V / 5 A) | Laptops, monitors |
| USB PD 3.1 | 240 W (48 V / 5 A) | High-power laptops, monitors |
PD negotiation happens between the charger and device. A 100 W charger will not force 100 W into a 18 W phone — the device requests what it needs.
Physical dimensions
| Measurement | Value |
|---|---|
| Plug width | 8.25 mm |
| Plug height | 2.4 mm |
| Reversible | Yes — no wrong way to insert |
| Contacts | 24 pins (all USB 3.x features use additional pins) |
How to identify your USB-C port's capability
- Check the laptop/device spec sheet. Port speeds and PD wattage are usually listed per port.
- A small ⚡ symbol next to the port indicates Thunderbolt.
- A numbers like 10 Gbps or 40 Gbps may be printed near the port.
- On desktop PCs, a USB-C port on a budget motherboard is likely USB 3.2 Gen 1. On a current premium laptop, it's likely Thunderbolt 4.