US to UK Size Converter
US to UK Size Converter
Half sizes are supported. Select the size that best matches your current shoe.
Select Your Size
Choose a category above, then select your US size to see the UK equivalent and more international sizes.
Convert US sizes to UK equivalents for shoes, clothing, bras, rings, and hats
Shopping internationally or ordering from a UK retailer? Figuring out the right size can be frustrating when the US and UK systems use completely different numbering conventions. Our US to UK Size Converter is an all-in-one tool that handles every major clothing and accessory category — shoes (men's, women's, and kids'), tops and pants, bras, rings, and hats — so you never have to guess your size again. The difference between US and UK sizing might seem small, but getting it wrong means returns, exchanges, and disappointment. For shoes, men's UK sizes are typically one full size smaller than US sizes (US 10 = UK 9), while women's UK sizes are two full sizes smaller (US 8 = UK 6). Children's shoe sizing follows similar patterns but varies by age group, from infants all the way through big kids. Our converter includes complete size tables for all five kids' categories, covering everything from size 0 infant shoes up through youth size 7. For clothing, the US and UK systems diverge more significantly. A US women's size 8 becomes a UK size 12, and a US size 0 corresponds to a UK size 4. Men's tops use the same letter sizing in both countries (S, M, L, XL), but pant waist measurements are identical in inches — it's the European conversion that changes. Our clothing converter also includes the international letter size (XS through 3XL) and European numeric size for every entry, giving you a complete reference in a single lookup. Bra sizing is one of the most commonly misunderstood conversions. While band sizes are identical between the US and UK (both measured in inches), cup sizes diverge significantly above a D cup. US DD becomes UK E, US DDD becomes UK F, US G becomes UK FF, and so on. Shopping for lingerie from UK brands without knowing this difference can result in a cup size that is dramatically off. Ring sizes use an entirely different system in the UK — alphabetical letters instead of US numeric sizes. US size 6 is UK L, US size 7 is UK N, and US size 9 is UK R. Our ring converter also shows the inner diameter and circumference in millimetres, which is handy when buying from European or Asian jewellers who use the metric Mondopoint system. Hat sizing is the simplest of the categories — US and UK hat sizes use the same numeric value, derived from head circumference divided by pi. The European system uses the head circumference directly in centimetres, so a US/UK size 7 equals an EU 56. Our hat size converter includes the EU equivalent and head circumference in centimetres for every US/UK size from 6 3/8 to 8. Whether you're shopping from ASOS, Marks & Spencer, Selfridges, John Lewis, or any other UK retailer, this tool gives you instant, accurate conversions across all size categories. Bookmark it for your next international shopping trip, and never order the wrong size again.
Understanding US vs UK Sizing
Why Do US and UK Sizes Differ?
The United States and United Kingdom developed their clothing and footwear sizing standards independently over many decades, resulting in systems that often use the same numbers to mean entirely different things. US shoe sizes are rooted in the Barleycorn system (each size increment equals one third of an inch or about 8.46 mm), a system also used in the UK, but starting from a different baseline point. For women's shoes, the US system assigns sizes that are two full increments higher than UK sizes for the same foot length. For men's shoes, it's one increment higher. Clothing sizes diverged even further, with the UK adopting a higher number scale for women's clothing — what Americans call a size 8 dress is sold as a size 12 in UK shops.
How Are Conversions Calculated?
Shoe conversions use standardised lookup tables that have been compiled from manufacturer data and international standards bodies. The general formulas are: Men's UK = US - 1; Women's UK = US - 2; Children's UK = US - 1. EU sizes are approximated using: Men's EU = US + 33; Women's EU = US + 31 (with some variation at half sizes). Foot length in centimetres is derived from the Mondopoint standard. Clothing conversions are fixed lookup table relationships — there is no simple arithmetic formula because the size systems evolved separately. Bra band sizes are identical in inches in both systems; only cup letters diverge above D. Ring sizes use the formula: UK alphabetical position corresponds to a specific inner diameter, with each letter increment equal to approximately 1.25 mm in diameter.
Why Getting Your Size Right Matters
International online shopping has made it easier than ever to buy from UK and European retailers, but the size confusion that comes with it leads to billions of dollars in returns worldwide each year. Getting the right shoe size matters for foot health — wearing a shoe even half a size too small can cause blisters, bunions, and long-term joint problems. Clothing that's one size too small is uncomfortable and unflattering, while clothing that's too large looks sloppy and may not be returnable if it was a sale item. For jewellery, a ring that's even a quarter size too small is impossible to wear, and resizing can damage delicate settings. Knowing your UK size before placing an order saves you the hassle and cost of international returns, which can sometimes cost as much as the item itself.
Limitations and Brand Variation
Size conversion tables are guides, not guarantees. Individual brands — both US and UK — size their garments and footwear differently even within the same country. A UK size 12 from Marks & Spencer may fit differently from a UK size 12 from Topshop. Athletic footwear tends to run slightly larger than dress shoes, so many professionals recommend sizing up half a size for running shoes. When feet differ in size, always size to the larger foot. Bra sizing varies significantly by brand and style — a T-shirt bra from one manufacturer may fit quite differently from a push-up bra in the same numeric size. For the most accurate result, use this converter as a starting point, then consult the specific retailer's size guide and, where possible, their customer reviews for sizing feedback.
Size Conversion Formulas
Men's UK Shoe Size
UK = US − 1
Men's UK shoe sizes are one full size smaller than the equivalent US size. A US men's 10 converts to UK 9.
Women's UK Shoe Size
UK = US − 2
Women's UK shoe sizes are two full sizes smaller than the US equivalent. A US women's 8 converts to UK 6.
Approximate EU Shoe Size (Men)
EU ≈ US + 33
A rough approximation for converting US men's shoe sizes to EU sizes. Exact values vary by half-size increments.
Women's Clothing Size Offset
UK = US + 4
UK women's clothing sizes are four numbers higher than the US equivalent. A US size 8 dress becomes a UK size 12.
Size Reference Tables
US to UK Shoe Sizes (Men & Women)
Standard shoe size conversions for adult men's and women's sizes, including EU equivalents.
| US Men | UK Men | EU Men | US Women | UK Women | EU Women |
|---|---|---|---|---|---|
| 6 | 5 | 39 | 5 | 3 | 35.5 |
| 7 | 6 | 40 | 6 | 4 | 36.5 |
| 8 | 7 | 41 | 7 | 5 | 37.5 |
| 9 | 8 | 42 | 8 | 6 | 39 |
| 10 | 9 | 43 | 9 | 7 | 40 |
| 11 | 10 | 44.5 | 10 | 8 | 41 |
| 12 | 11 | 45.5 | 11 | 9 | 42.5 |
| 13 | 12 | 47 | 12 | 10 | 43.5 |
| 14 | 13 | 48 | — | — | — |
| 15 | 14 | 49 | — | — | — |
US to UK Women's Clothing Sizes
Standard women's clothing size conversions from US numeric sizes to UK and international letter sizes.
| US Size | UK Size | Int'l Letter | EU Size |
|---|---|---|---|
| 0 | 4 | XS | 32 |
| 2 | 6 | XS | 34 |
| 4 | 8 | S | 36 |
| 6 | 10 | S/M | 38 |
| 8 | 12 | M | 40 |
| 10 | 14 | M/L | 42 |
| 12 | 16 | L | 44 |
| 14 | 18 | L/XL | 46 |
| 16 | 20 | XL | 48 |
| 18 | 22 | XXL | 50 |
| 20 | 24 | 3XL | 52 |
Worked Examples
Convert US Men's Size 10 Shoes to UK
A man wears US size 10 shoes and wants to order from a UK retailer.
Apply the men's shoe formula: UK = US − 1
UK = 10 − 1 = 9
Check the EU equivalent: EU ≈ 10 + 33 = 43
Foot length is approximately 28 cm (11 inches)
US men's 10 = UK 9 = EU 43. Order a UK size 9 from the retailer.
Convert US Women's Dress Size 8 to UK
A woman wears US size 8 dresses and is shopping on a UK fashion website.
Apply the women's clothing formula: UK = US + 4
UK = 8 + 4 = 12
The international letter size for this range is M
EU equivalent is approximately 40
US women's size 8 = UK 12 = EU 40. Select UK 12 or Medium when ordering.
Convert US Women's Size 7 Shoes to UK
A woman wears US size 7 shoes and wants to buy trainers from a British brand.
Apply the women's shoe formula: UK = US − 2
UK = 7 − 2 = 5
EU equivalent is approximately 37.5–38
Foot length is approximately 23.8 cm
US women's 7 = UK 5 = EU 37.5. Order a UK size 5.
How to Use This Converter
Select a Category
Click one of the five category tabs at the top: Shoes, Clothing, Bra, Ring, or Hat. Each tab shows the relevant inputs for that size type.
Choose Your Options
For shoes, select your gender (Men, Women, or Kids) and your kids' age group if applicable. For clothing, choose your gender and clothing type (tops or pants).
Enter Your US Size
Select your current US size from the dropdown. Shoe sizes include half-size increments. Bra sizes need both band size and cup size selected.
Read Your UK Size
Your UK equivalent appears instantly in the results panel, along with EU size and additional measurements. Use the Copy button to save the result for reference when shopping.
Frequently Asked Questions
What is the difference between US and UK shoe sizes?
US and UK shoe sizes use the same Barleycorn increment system (each size = 1/3 inch), but with different starting points. For men's shoes, UK sizes are one full size smaller than US sizes — so a US men's 10 is a UK 9. For women's shoes, UK sizes are two full sizes smaller — a US women's 8 is a UK 6. This means a man and a woman with the same foot length would wear different US sizes but the same UK size. Children's shoes follow the men's pattern, with UK sizes typically one smaller than US.
Are US and UK women's clothing sizes the same?
No — US and UK women's clothing sizes are quite different. UK women's clothing sizes are generally four numbers higher than the equivalent US size. So a US size 4 is a UK size 8, a US size 8 is a UK size 12, and a US size 14 is a UK size 18. Both systems increase by 2 with each size step. The European sizing system uses a completely different scale based on body measurements in centimetres. Always check the specific retailer's size guide, as individual brands may vary from these standard conversions.
How do bra cup sizes differ between the US and UK?
Bra band sizes are identical between the US and UK systems — both use inches. The difference only appears in cup sizes beyond D. US DD corresponds to UK E, US DDD (or F) corresponds to UK F, US G corresponds to UK FF, US H corresponds to UK G, US I corresponds to UK GG, US J corresponds to UK H, and US K corresponds to UK HH. Below DD, the cup letters are the same in both systems (A, B, C, D). This difference means that if you're a 34DD in the US and buy from a UK lingerie brand without converting, you would need to look for a 34E.
How are UK ring sizes different from US ring sizes?
UK ring sizes use an alphabetical letter system (F through Z+), while US ring sizes use a numeric scale (3 to 13 or higher). The two systems do not share a simple arithmetic formula — they require a lookup table. For example, US size 5 equals UK J, US size 7 equals UK N, and US size 9 equals UK R. Each UK letter corresponds to a specific inner diameter in millimetres, with approximately 1.25 mm between each letter. When buying rings from UK or European jewellers, always convert your US size to the correct UK letter to ensure the best fit.
Are US and UK hat sizes the same?
Yes — US and UK hat sizes use exactly the same numeric values, derived from the head circumference divided by pi. A US size 7 hat and a UK size 7 hat refer to the same head measurement. The European hat sizing system is different — it simply uses the head circumference in centimetres. So a US/UK size 7 equals approximately an EU 56 (56 cm circumference). When shopping for hats from UK retailers, you do not need to convert — just use your US size directly. However, if the hat uses EU sizing, you will need the centimetre conversion.
Why do different brands fit differently even in the same size?
Clothing and footwear sizing standards are guidelines, not legally mandated measurements. Individual brands adjust their patterns and lasts (the foot-shaped forms used to construct shoes) based on their target customer, design aesthetic, and manufacturing processes. A UK size 12 dress from one high-street brand may be cut more generously than the same size from another. Athletic footwear tends to run slightly larger than dress shoes due to the thicker socks typically worn with them. This is why size conversion tables should always be treated as a starting point — consulting the specific brand's size guide, checking customer reviews for fit feedback, and measuring yourself against the brand's measurement chart will give the most accurate result.
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