BIPM-ratified constants · v1.0

Converter

Uk, to us shoe size converter calculator.

Free UK to US shoe size converter for men, women, and kids. Uses the standard +1 offset for men's and +2 for women's sizing.

From

uk_to_us

8 uk_to_us =9Converted Shoe Size

Equivalents

Precision: 6 dp · Notation: Decimal · 3 units

Men'smen9

Women'swomen10

Kids'kids9

Common pairings

1 uk_to_usequals2 men

1 uk_to_usequals3 women

1 uk_to_usequals2 kids

1 us_to_ukequals0 men

1 us_to_ukequals-1 women

1 us_to_ukequals0 kids

The conversion

How the value
is computed.

How the UK to US Shoe Size Converter Works

Converting shoe sizes between the United Kingdom and the United States relies on a simple arithmetic offset. Both systems use the same base unit — one-third of an inch per size increment — but their numbering sequences begin at different points, creating a fixed numerical gap that a single formula resolves.

The Core Conversion Formula

The offset differs by sizing category because each country calibrated its scale independently for men's and women's footwear:

Men's (UK to US): US size = UK size + 1
Women's (UK to US): US size = UK size + 2
Men's (US to UK): UK size = US size − 1
Women's (US to UK): UK size = US size − 2

Why the Offsets Differ Between Men's and Women's

The two-size gap for women's versus the one-size gap for men's reflects a historical difference in how each country set the zero point of its numbering sequence. US women's sizing begins at a lower foot-length baseline than US men's, pushing the numerical value two steps higher relative to the UK baseline rather than one. This is a structural feature of independently developed national standards — not a rounding error — and it remains consistent across all major footwear brands.

Variables Explained

Shoe Size to Convert (value): Enter the numeric size printed inside the shoe or listed on the product page in the source country's system. Half sizes such as 9.5 are fully supported and follow the same offset rule.
Conversion Direction (direction): Select UK to US or US to UK. The reverse direction simply subtracts the offset instead of adding it.
Sizing Category (gender): Select men's, women's, or children's. Applying a men's offset to a women's size produces an incorrect result, so this selection is required for accuracy.

Worked Examples

UK men's size 9 → US men's size 10 (9 + 1 = 10)
UK women's size 6 → US women's size 8 (6 + 2 = 8)
UK men's size 11.5 → US men's size 12.5 (11.5 + 1 = 12.5)
UK women's size 7.5 → US women's size 9.5 (7.5 + 2 = 9.5)
US men's size 13 → UK men's size 12 (13 − 1 = 12)
US women's size 9 → UK women's size 7 (9 − 2 = 7)

Common Real-World Scenarios

This converter is essential for cross-border shoe shopping. Key use cases include purchasing from UK retailers such as ASOS, Clarks, or John Lewis while based in the United States, buying from US brands while residing in the UK, verifying a size on a multi-national product page that lists both UK and US columns, and confirming a fit when purchasing second-hand footwear from international sellers on platforms like eBay or Depop.

Important Fit Considerations Beyond Size

While the size conversion formula is consistent, shoe fit depends on additional factors beyond numerical size. Width fittings, arch support profiles, and heel-to-toe proportions vary significantly by brand and shoe category. A UK size 7 women's running shoe from one manufacturer may feel different from a UK size 7 ballet flat or casual trainer from another brand, even after converting to US sizing. Always consult the specific brand's international size guide and read customer reviews mentioning fit and comfort. Return policies differ between retailers and countries, so verify the terms before purchasing from an unfamiliar seller. When buying shoes online across borders, measuring your foot length in millimeters and comparing it against the brand's detailed size chart — rather than relying solely on the numerical offset — significantly improves the accuracy of your selection and reduces the likelihood of returns.

Sources and Methodology

The +1 men's and +2 women's offsets are confirmed by the official size guides of leading global footwear brands. Nike's official men's footwear size chart lists UK and US equivalents side by side, showing a consistent one-size difference across the full men's range. Adidas's international size charts confirm the two-size offset for women's sizing between UK and US numbering systems. Academic support for these linear offset values can also be found in Beginning Algebra Made Useful (GVSU ScholarWorks), which uses US and international shoe size tables as a real-world linear algebra application, illustrating the fixed additive relationship between sizing systems.

Reference

Frequently asked questions

What is a UK men's size 8 in US shoe sizing?

A UK men's size 8 converts to a US men's size 9. The standard formula adds 1 to the UK size for men's footwear: 8 + 1 = 9. This offset is uniform across the entire men's range — for example, UK 6 equals US 7, UK 10 equals US 11, and UK 13 equals US 14.

What is a UK women's size 6 in US shoe sizing?

A UK women's size 6 converts to a US women's size 8. Women's sizing uses a +2 offset: 6 + 2 = 8. This two-size difference applies across the full women's range. UK 4 becomes US 6, UK 7 becomes US 9, and UK 9 becomes US 11, all following the same consistent rule.

Do half sizes convert the same way between UK and US shoes?

Yes, half sizes follow the identical offset. A UK men's size 9.5 becomes US men's size 10.5 (9.5 + 1 = 10.5), and a UK women's size 6.5 becomes US women's size 8.5 (6.5 + 2 = 8.5). Major brands including Nike and Adidas produce half sizes and list them with the same consistent offset on their official international size charts.

Why do men's and women's UK to US shoe conversions use different offsets?

The difference exists because the United States and United Kingdom independently calibrated their sizing scales at different historical starting points. US women's sizing begins numbering at a lower foot-length baseline than US men's, which places the numerical value two steps higher against the UK scale rather than one. This structural divergence in national standards has remained consistent across all major footwear manufacturers and is not a measurement error.

How do I convert US shoe sizes back to UK sizes?

Reverse the formula by subtracting the offset. For men's footwear, UK size = US size minus 1. For women's footwear, UK size = US size minus 2. Examples: US men's size 12 becomes UK men's size 11 (12 − 1 = 11); US women's size 10 becomes UK women's size 8 (10 − 2 = 8). Half sizes follow the same subtraction rule.

Are UK and US children's shoe sizes converted the same way as adults?

No — children's sizing uses a different offset from adult sizing. For young children and toddlers, UK and US sizes are often the same number or separated by only half a size, unlike the one-to-two size gap seen in adult footwear. Because children's offsets vary more by age group and brand, it is best to verify against a specific brand's published kids' international size chart rather than applying a fixed adult formula.