Shopping for shoes internationally can be confusing. A US size 9 is not the same as a UK size 9 or an EU size 9. Each country or region uses a different sizing standard based on different measurement systems, and ISO 19407:2023 explicitly notes that the different systems have been developed and interpreted over many years without being formalized. Whether you are buying shoes from a foreign retailer, a European brand, or an athletic company that lists sizes differently, a shoe size conversion tool helps you find the right fit without guesswork. ISO 9407:2019, the Mondopoint standard, was confirmed as current in June 2026 and remains the international standard for footwear sizing based on foot length in millimeters.
What This Calculator Does
Select your gender and current size system, then choose your size. The calculator instantly shows the equivalent in all major sizing standards including US, UK, EU, and foot length in centimeters and inches.
For related conversion tools, try our Height Calculator for converting between centimeters and feet/inches, or our BMI Calculator for health assessments. You can also use our Percentage Calculator for calculating discounts when shopping for shoes online.
Inputs Required
- Gender: Men or Women (sizing systems differ by gender)
- Size System: The system you already know your size in (US, UK, EU, or cm)
- Your Size: Your known shoe size in that system
Outputs Provided
- US Size: North American standard sizing
- UK Size: British standard sizing
- EU Size: European (Paris Point) sizing
- Foot Length in cm and inches: The actual foot measurement
How the Calculation Works
Shoe sizes are based on the length of the last (the mold used to shape the shoe) rather than the exact foot length. ISO/TR 25295:2025, the global last measurement systems guide, documents that 10 mm intervals are commonly referred to as whole sizes and 5 mm intervals as half sizes. Each sizing system uses a different unit and starting point.
- US sizing is based on barleycorn units (1/3 inch), with a starting offset for men and women. King Edward II (1284 to 1327) is often credited with introducing this system
- UK sizing uses the same barleycorn unit but starts at a different offset (usually 1 size smaller than US for men)
- EU sizing uses Paris Points (2/3 of a centimeter per size unit), also known as continental sizing
- Mondopoint (ISO 9407:2019) uses foot length in millimeters directly, eliminating conversion ambiguity. It is commonly used for ski boots and military footwear
EU Size = (Foot Length in cm / 0.667) + 2 (approximate)
US Men = UK + 0.5 (approximate)
Mondopoint = Foot Length in mm (direct measurement)
How to Use the Calculator
- Select whether you are shopping for men's or women's shoes
- Choose the size system you currently know your size in
- Select your size from the dropdown
- View all equivalent sizes instantly
- Use the full size chart at the bottom for a broader reference
Example Conversion
A man who wears US size 10 is shopping at a Spanish shoe store that uses EU sizing:
- US: 10
- UK: 9.5
- EU: 44
- Foot Length: 27.5 cm / 10.8 inches
- Mondopoint: 275 mm
Real-World Scenarios
Buying Running Shoes from a German Brand in Portland
A 29-year-old software developer in Portland wants to order a pair of Adidas running shoes from a German website that lists sizes in EU only. She knows her US women's size is 8.5. Using the calculator, she finds that US women's 8.5 converts to EU 39.5, UK 6, and a foot length of approximately 25.1 cm. The German site does not offer half sizes in this model, so she sizes up to EU 40, which corresponds to US 9. She checks the brand's specific fit guide and finds that this model runs small, confirming that sizing up is the right call. Without the conversion tool, she would have guessed and likely needed a return.
Buying Dress Shoes as a Gift in Boston
A man in Boston is buying dress shoes online as a gift for his wife. He knows she wears EU size 38 but the American retailer only lists US sizes. The calculator confirms that EU 38 converts to US women's 7.5, UK 5.5, and a foot length of approximately 23.8 cm. He orders the US 7.5. The shoes fit perfectly. He also checks the retailer's return policy, because ISO 19407:2023 notes that conversions are guidelines, not exact equivalents, and brand-specific lasts can vary by up to a full size.
Ski Boot Sizing Using Mondopoint in Denver
A 35-year-old skier in Denver is buying new ski boots, which use the Mondopoint system (ISO 9407:2019). The boot shell lists 305 mm, but he only knows his US men's size is 10.5. Using the calculator, he finds that US men's 10.5 corresponds to a foot length of approximately 28.3 cm, or 283 mm in Mondopoint. He tries on boots in the 283 to 288 mm range and finds that 285 mm provides the snug performance fit he needs for advanced skiing. The Mondopoint system eliminates the ambiguity of US, UK, and EU conversions by using direct foot length measurement.
Common Mistakes to Avoid
- Assuming all systems are offset by the same amount: Men's and women's conversions use different offsets. A women's US 8 is approximately a men's US 6.5, not the same size. Always specify gender when converting
- Ignoring half sizes: Not all brands offer half sizes in all systems. ISO/TR 25295:2025 documents that 5 mm intervals correspond to half sizes. When in doubt, size up rather than down, especially for athletic shoes
- Not accounting for shoe type: Athletic shoes, dress shoes, and boots may fit differently even in the same size. ISO 19407:2023 explicitly states that its conversion tables are guidelines, not exact equivalents, because last shapes vary by manufacturer and shoe type
- Confusing Australian sizing: Australian women's sizing aligns with US sizing, but Australian men's sizing aligns with UK sizing, which is about half a size smaller than US for men. This is a common source of fit errors for online shoppers
Limitations of This Calculator
This calculator provides conversion guidelines based on standard sizing relationships. ISO 19407:2023 explicitly notes that shoe size conversions are guidelines, not exact equivalents, because each system has been developed and interpreted over many years without formalization. The calculator does not account for width fittings (narrow, standard, wide, extra wide), which ISO/TR 25295:2025 documents as a separate dimension with 7 mm intervals for whole sizes and 3.5 mm for half sizes. Brand-specific lasts can vary by up to a full size from the standard conversion. The calculator does not cover children's sizing, specialty sizing (such as orthopedic or extra-depth footwear), or regional variations within systems (for example, Italian versus German EU sizing). Always check the brand's specific size chart when available, and consider foot width and arch type in addition to length.
Authoritative Research and Resources
- ISO 19407:2023: Footwear, Sizing, Conversion of Sizing Systems - The international standard providing three shoe size conversion tables covering Mondopoint, European, UK, China, Japan, Republic of Korea, and US systems. ISO notes that these tables are guidelines because the systems were developed without formalization.
- ISO 9407:2019: Footwear Sizing, Mondopoint System - The international standard for footwear sizing based on foot length in millimeters, confirmed as current in June 2026. Mondopoint eliminates conversion ambiguity by using direct measurement and is commonly used for ski boots and military footwear.
- ISO/TR 25295:2025: Footwear, Global Last Measurement Systems Guide - A technical report documenting standardized last dimensions, grading intervals (10 mm for whole sizes, 5 mm for half sizes), and width measurements across global footwear manufacturing systems.