Romper Size Conversion Chart

How romper size conversion works

Size systems use different labels for the same body measurements. The US system uses letters such as S, M and L and numbers such as 6, 8 and 10, the UK system uses numbers such as 10, 12 and 14, and the EU system uses numbers such as 38, 40 and 42. A conversion chart lines those labels up by the bust, waist and hip ranges behind them, so you can move from one system to another without guessing.

The match is always approximate. Two brands in the same system can cut the same label differently, and a brand that sells in several systems may grade its romper differently for each market. Treat the conversion as a starting point, then check your own measurements against the brand chart in the system the brand actually uses for that romper.

The general conversion table

The table below lines up broad adult romper sizes across the US, UK and EU systems, with the bust, waist and hip ranges that sit behind each row. Use your measurements to find your row, then read across to the label you need. If your measurements span two rows, start with the row that covers your largest measurement, because a romper must fit the widest area that affects it.

Number sizes add another layer. A US 8 is broadly a UK 12 and an EU 40, while a US 10 is broadly a UK 14 and an EU 42, but some brands skip numbers or use even numbers only. When a brand lists both a letter and a number, use the number if you can, because numbers carry a little more detail than letters, and check the stated garment measurements as well.

Converting between letters and numbers

Letter sizes group several number sizes together, so a letter covers a range rather than a single point. A US M usually covers US numbers 8 to 10, while a US L usually covers US numbers 12 to 14, and the same grouping applies in the UK and EU systems with their own numbers. That grouping is why a letter conversion feels rough, and why two people who both wear M can have quite different measurements.

If you know your number size in one system, convert through the measurement ranges rather than through the letter. Find the row whose bust, waist and hip ranges cover your numbers, then read the label in the system you need. The Romper Size Calculator estimates a starting letter size from your measurements, which you can then convert with the table below.

Ordering across systems without a fitting room

When you order from a brand in another system, start with fresh measurements in inches or centimetres, then open the brand chart and compare your numbers with the full row, not just the converted label. If the brand also lists torso length and inseam, compare those too, because a conversion table says nothing about torso length, and a romper with the wrong torso length will pull or sag.

Read the fit note as well as the chart. A brand that describes a style as fitted has already built a close cut into its sizes, so converting down on top of that can leave you with a romper that pulls at the crotch and strains across the bust. When the conversion is close and the fabric is firm, the larger of the two converted sizes is usually the safer starting point.

Romper size conversion table

The table below is a broad general guide. Always check the brand chart for the romper you are buying.