US to UK Suit Size Conversion
| US/UK Chest (in) | US/UK Chest (in) |
|---|---|
| 36 | 36 |
| 38 | 38 |
| 40 | 40 |
| 42 | 42 |
| 44 | 44 |
| 46 | 46 |
| 48 | 48 |
Sizing conventions vary by brand and by cut — this table shows the standard published conversion. Always check the garment's own size chart when one is available. See how these tables are compiled.
US and UK men's suit sizes are the same number — a US 40 jacket is a UK 40 — since both markets size suits by chest measurement in inches rather than by a separate national scale.
The genuine difference between a US-cut and UK-cut suit at the same labelled size is the cut itself: British tailoring has traditionally used a more structured shoulder and higher armhole than the softer, roomier American cut, which the size number alone doesn't capture.
Frequently asked questions
If US and UK suit sizes are the same number, why do the suits fit differently?
Cut, not size — British tailoring traditionally uses a more structured shoulder and higher armhole than the softer American cut, a stylistic difference the shared chest-inch number doesn't reflect.