Size comparison · UK womenswear
What a UK 18 really measures across UK shops
The label says 18. The tape measure disagrees. We read each retailer’s own published chart — and at UK 18 the waist moves 9 cm between Roman Curve and Yours Clothing. That is most of a dress size, on the same number on the tag.
The quick answer
- Waist at UK 18: 92 cm (Yours) to 101 cm (Roman Curve) — a 9 cm spread.
- Bust: 107 cm (Yours) to 111.5 cm (Roman Curve).
- Hips: 116 cm (Yours) to 118 cm (Roman Curve).
UK 18 across five shops — the real numbers
Every figure below is read directly from each retailer’s published size guide, in centimetres.
| Retailer | Bust | Waist | Hips |
|---|---|---|---|
| Yours Clothing | 107 cm | 92 cm | 116 cm |
| Simply Be | 110 cm | 95 cm | 116 cm |
| Dorothy Perkins | 111 cm | 93 cm | 119 cm |
| Boohoo | 111 cm | 93 cm | 119 cm |
| Roman Curve | 111.5 cm | 101 cm | 118 cm |
Sources: yoursclothing.co.uk, roman.co.uk (Curve chart), dorothyperkins.com, simplybe.co.uk, read 24 October 2026.
Why the Roman gap doesn’t close as sizes go up
Most shops step up about 4 cm at the waist per size. Roman Curve also steps up about 4 cm — but it starts roughly a size ahead, so the gap narrows without ever disappearing:
| Size | Roman Curve waist | Yours / DP waist | Gap |
|---|---|---|---|
| UK 16 | 97 cm | 87 cm | 10 cm |
| UK 18 | 101 cm | 92–93 cm | 8.5 cm |
| UK 20 | 105 cm | 98–99 cm | 6.5 cm |
In practice: if your waist is 101 cm, Roman Curve at UK 18 is your closest fit — but at Yours or Dorothy Perkins you would be looking at a UK 20.
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UK 18 questions, answered
What are the measurements for a UK size 18 in cm and inches?
Across the UK curve retailers we checked, a UK 18 bust measures 107–111.5 cm (42.1–43.9 inches), a natural waist measures 92–101 cm (36.2–39.8 inches), and full hips measure 116–119 cm (45.7–46.9 inches). The waist varies by up to 9 cm on the same label.
Does a UK 18 fit the same at Yours Clothing and Roman Curve?
No. Yours Clothing publishes a UK 18 with a 92 cm (36.2 inch) waist and 116 cm hips. Roman Curve publishes a 101 cm (39.8 inch) waist and 118 cm hips — 9 cm more waist room. If your waist is 101 cm, Roman Curve at UK 18 fits you; at Yours you would look at a UK 20.
Which UK shop has the narrowest UK 18 waist?
Dorothy Perkins and Boohoo publish the same chart: a 93 cm (36.6 inch) waist at UK 18. Simply Be sits between them at 95 cm. Roman Curve is the widest at 101 cm.
Is a UK 18 the same across all UK shops?
No. Bust and hips are close across shops at UK 18 — within 4.5 cm and 3 cm — but the waist moves 9 cm. The label is a starting point, not a size.