Shoe Size Converter

How Does the Formula Work?

The shoe size converter instantly translates between US, UK, EU, and centimeter (foot length) sizing systems for men, women, and children. Shoe sizing is one of the most confusing aspects of shopping — especially online and internationally — because each country uses a different system with no intuitive relationship between them. A US Men's 10 is a UK 9, an EU 43-44, and corresponds to a 27-28 cm foot. This converter eliminates the guesswork by calculating all systems simultaneously from any single input. Results include the size in all four systems plus the foot length in both centimeters and inches.

Understanding Shoe Size Systems

The EU system uses the Paris Point (each size = 2/3 cm or 6.67 mm). EU sizes are the same for men and women — an EU 42 is the same physical size regardless of gender. The US system uses the Brannock Device, invented in 1927 by Charles Brannock, which measures foot length in inches and converts using the formula: size = 3 × length_in_inches − 22 (men) or − 20.5 (women). This means US women's sizes are 1.5 larger than men's for the same foot length — a US Women's 9.5 equals a US Men's 8. The UK system is similar to US but offset by approximately 1 size (UK = US Men − 1). Japanese and Korean sizing uses centimeters directly (a 27 cm foot is size 27). Brazilian sizing (BR) is close to EU but typically 2 sizes smaller (EU 42 ≈ BR 40).

How to Measure Your Foot

Accurate measurement is essential because shoe sizes are approximations. Stand on a piece of paper with your heel against a wall. Mark the tip of your longest toe (which may not be your big toe — about 20 percent of people have a longer second toe, called Morton's toe). Measure the distance from the wall to the mark in centimeters. Measure both feet — they are often different sizes, and you should buy shoes for the larger foot. Measure in the afternoon or evening when feet are slightly swollen from daily activity. Wearing the socks you plan to use with the shoes can add 3-5 mm to the measurement. For width, measure the widest part of your foot — standard widths are B (narrow), D (standard for men, wide for women), and EE (wide for men).

Online Shopping Tips

Buying shoes online requires extra care because sizing varies between brands. Nike tends to run small — many people go half a size up. Adidas is generally true to size. New Balance offers multiple widths (rare among brands). European brands like Birkenstock use EU sizing that matches this converter well. When ordering from international retailers, always convert to centimeters first (the most universal measurement), then use the brand's specific size chart if available. Many online stores now offer free returns, making it practical to order two sizes and return the one that does not fit. Read reviews for brand-specific sizing advice — phrases like "runs small" or "runs large" indicate you should adjust.

Children's Sizing

Children's shoe sizes are particularly confusing because kids' feet grow rapidly — about 1 mm per month for toddlers and 0.7 mm per month for school-age children. US children's sizes run from 0 (newborn) to 13.5, then jump to US 1 (youth) which is an entirely different scale. EU children's sizes start around 16-17 (newborn) and go up to about 35-36 before transitioning to adult sizing. Always measure children's feet before buying — do not assume they need the next size up from their last pair. A thumbnail width of space (about 1 cm) between the longest toe and the front of the shoe allows room for growth. Replace children's shoes every 3-4 months for toddlers and every 4-6 months for older children.

Foot Health and Proper Fit

Wearing incorrectly sized shoes causes more problems than most people realize. Shoes that are too small can cause bunions, hammertoes, ingrown toenails, corns, and nerve damage (Morton's neuroma). Shoes that are too large cause blisters from friction and instability that can lead to ankle sprains. The American Orthopaedic Foot and Ankle Society estimates that 88 percent of women and 72 percent of men wear shoes that are too small. A properly fitted shoe should have about 1 cm (a thumb's width) of space between your longest toe and the front of the shoe, should not pinch anywhere, and should secure your heel without slipping. Different activities require different fits — running shoes need more toe room than dress shoes.

Athletic Shoe Sizing

Athletic shoes require special sizing attention. Running shoes typically need a half to full size larger than dress shoes because feet swell during exercise. The American Academy of Podiatric Sports Medicine recommends having a thumbnail's width between your longest toe and the front of the running shoe. Basketball shoes need ankle support so should fit snugly. Soccer cleats should fit tighter than casual shoes for ball control. Hiking boots need room for thick socks plus toe space for downhill sections to prevent black toenails. This converter gives you the baseline size — then adjust based on activity and brand recommendations.