USB Cheat Sheet
| Marketing Name | Also Known As | Signal Gbps | Signal MiB/s | Wires | Cable |
|---|---|---|---|---|---|
| USB 1.1 | Full Speed | 12 Mbps | 1.5 MiB/s | 4 | 4m |
| USB 2.0 | Hi-Speed | 480 Mbps | 60 MiB/s | 4 | 4m |
| SuperSpeed USB 5Gbps | USB 3.0 USB 3.1 USB 3.2 USB 3.1 Gen 1 USB 3.2 Gen 1 |
5000 Mbps | 625 MiB/s | 8 | 3m |
| SuperSpeedPlus USB 10Gbps | USB 3.1 USB 3.2 USB 3.1 Gen 2 USB 3.2 Gen 2 |
10000 Mbps | 1250 MiB/s | 8 | 2m |
| SuperSpeedPlus USB 20Gbps | USB 3.2 USB 3.2 Gen 2x2 |
20000 Mbps | 2500 MiB/s | 12 | 1m |
| USB4 20Gbps | USB4 Gen 2×2 USB4 |
20000 Mbps | 2500 MiB/s | 12 | 0.8m |
| USB4 40Gbps | USB4 Gen 3×2 USB4 |
40000 Mbps | 5000 MiB/s | 12 | 0.8m |
Gen naming Convention, lanes, and Speed
USB Gen A x B
A = Generation
B = Num lanes used
| Name | Signal | Sig Totala | Encoding | Effective bb | Effective Bb | Real Lifec |
|---|---|---|---|---|---|---|
| USB 3.2 Gen 1x1 | 5,000 Mbps | 5,000 Mbps | 8b/10b | 4,000 Mbps | 500 MiB/s | 400 MiB/s[1|1] |
| USB 3.2 Gen 1x2 | 5,000 Mbps | 10,000 Mbps | 8b/10b | 8,000 Mbps | 1,000 MiB/s | 800 MiB/s |
| USB 3.2 Gen 2x1 | 10,000 Mbps | 10,000 Mbps | 128b/132b | 9,696 Mbps | 1,212 MiB/s | 780 MiB/s[2|2] |
| USB 3.2 Gen 2x2 | 10,000 Mbps | 20,000 Mbps | 128b/132b | 19,392 Mbps | 2,424 MiB/s | 1,600 MiB/s[4|4] |
| USB 4 Gen 2x2 | 10,000 Mbps | 20,000 Mbps | 128b/132b | 19,392 Mbps | 2,424 MiB/s | 1,600 MiB/s |
| USB 4 Gen 3x2 | 20,000 Mbps | 40,000 Mbps | 128b/132b | 38,787 Mbps | 4,848 MiB/s | 2,700 MiB/s[5|5] |
Note: Multi-lanes systems, uses lane striping (on TX) and lane bonding (on RX).
a - What they put on the box.
b - Rate with encoding overhead. e.g, 8b/10b = 20%.
c - Real life sequential read rate.
Cables
4 wires: PWR, GND, D+, D-.
8 wires: PWR, GND, D+, D-. RX+ , RX- , TX- , TX+.
12 wires: PWR, GND, D+, D-, RX1+, RX1-, RX2-, RX2+, TX1+, TX1-, TX2-, TX2+.
Note: 1 USB lane = 1 twisted wire pair +/-.
Note: 4 wires = 1 half-duplex lane, 8 wires = 2 lanes (one up, one down), and 12 wires = 4 lanes (two up, two down).
USB-A/B: Connectors 4/8 wires
| Type-A 4-wires | Type-A 8-wires | Type-B 4-wires | Type-B 8-wires |
|---|---|---|---|
 |
 |
 |
 |
USB-C: Connectors 12 wires
Only the USB Type-C connector has enough pins to support two lanes.
CC1 and CC2 are downstream facing port (DFP) and upstream facing port (UFP) detection. Also used for power negotiation and alt mode switch.
- SBU1 and SBU2 are secondary bus wires, for the DisplayPort AUX channel and hot plug detection (HPD).
Charge rates / Cable types
| Specifications | Max. Voltage | Max. Current | Max. Power |
|---|---|---|---|
| USB 2.0 | 5V | 500mA | 2.5W |
| USB 3.0 / USB3.1 | 5V | 900mA | 4.5W |
| USB Battery Charging (BC) 1.2 | 5V | 1.5A | 7.5W |
| USB-C Current Mode (non-PD) | 5V | 3A | 15W |
| USB-C / Power Delivery (PD 1/2) | 20V | 5A | 100W |
| USB-C PD 3.1 (EPR) | 48V | 5A | 240W |
Specifications
USB 1.0 (Jan, 1996).
USB 1.1 (Sep, 1998).
USB 2.0 (Apr, 2000).
USB 3.0 (Nov, 2008).
USB 3.1 (Jul, 2013).
USB 3.2 (Sep, 2017).
USB 4.0 (Aug, 2019).