How the US and UK Systems Compare
Both the US (Brannock) and UK (British) sizing systems descend from the English barleycorn unit — one-third of an inch per full size, with half-sizes in between. The only real difference is the zero point: the US system starts counting from a slightly different baseline, which is why US Men's sizes are approximately 1 higher than UK sizes for the same foot length. US Women's sizes are about 2 higher than UK sizes.
The precise formulas are: US Men = 3 × foot (in) − 22 and UK = 3 × foot (in) − 23. The 1-unit offset means US Men ≈ UK + 1 for men, and US Women ≈ UK + 2 for women.
US Women's to UK Conversion Chart
| US Women's | UK | cm |
|---|---|---|
| 4 | 2 | 21.2 |
| 4.5 | 2.5 | 21.6 |
| 5 | 3 | 22 |
| 5.5 | 3.5 | 22.4 |
| 6 | 4 | 22.9 |
| 6.5 | 4.5 | 23.3 |
| 7 | 5 | 23.7 |
| 7.5 | 5.5 | 24.1 |
| 8 | 6 | 24.6 |
| 8.5 | 6.5 | 25 |
| 9 | 7 | 25.4 |
| 9.5 | 7.5 | 25.8 |
| 10 | 8 | 26.2 |
| 10.5 | 8.5 | 26.7 |
| 11 | 9 | 27.1 |
| 11.5 | 9.5 | 27.5 |
| 12 | 10 | 27.9 |
US Men's to UK Conversion Chart
| US Men's | UK | cm |
|---|---|---|
| 6 | 5 | 23.7 |
| 6.5 | 5.5 | 24.1 |
| 7 | 6 | 24.6 |
| 7.5 | 6.5 | 25 |
| 8 | 7 | 25.4 |
| 8.5 | 7.5 | 25.8 |
| 9 | 8 | 26.2 |
| 9.5 | 8.5 | 26.7 |
| 10 | 9 | 27.1 |
| 10.5 | 9.5 | 27.5 |
| 11 | 10 | 27.9 |
| 11.5 | 10.5 | 28.4 |
| 12 | 11 | 28.8 |
| 12.5 | 11.5 | 29.2 |
| 13 | 12 | 29.6 |
| 13.5 | 12.5 | 30.1 |
| 14 | 13 | 30.5 |
Worked Examples
- US Men's 10 → UK 9: foot = 10.7 in (27.1 cm). UK = 3 × 10.7 − 23 = 9.
- US Women's 8 → UK 6: foot = 9.7 in. UK = 6.
- US Men's 7 → UK 6: foot = 9.7 in. UK = 6.
Common Mistakes
- Using “subtract 1” for women: The 1-size offset applies to men's only. For women's US-to-UK, subtract 2.
- Mixing up UK and US kids' sizing: Children's sizes use a different formula entirely. Don't apply adult rules to kids' shoes.
- Forgetting half sizes exist: Both US and UK systems use half sizes. Rounding to the nearest whole number may put you a half size off.
Enter a US size in the shoe size converter to get the UK equivalent plus EU, Japan, and China sizes.