UK to US Maternity Size Conversion
| UK | US |
|---|---|
| 6 | XS |
| 8 | S |
| 10-12 | M |
| 14-16 | L |
| 18-20 | XL |
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.
A UK 12 maternity item matches a US 8 on the standard chart, since maternity brands base their sizing on the wearer's ordinary pre-pregnancy dress size rather than a scale of their own.
Maternity fit needs shift by trimester and by where a person carries in a way regular dress sizing simply doesn't have to account for, so a specific brand's own bump-room notes (some cut noticeably more room through the belly panel than others at the same nominal size) are worth reading before you order rather than assuming the size number tells the whole story.
Frequently asked questions
Does maternity sizing change across trimesters?
The size label typically doesn't, but how much room a specific brand builds into the belly panel varies — some maternity lines are cut for more growth room than others at the same converted size.