Shoe Size Converter

Three major sizing systems coexist globally, and none of them are fully compatible without conversion. The US system uses different number sequences for men and women, with a 1.5-size gap between them — a Men's 8 and a Women's 9.5 accommodate the same foot length. The UK system follows a similar barleycorn (⅓ inch) unit but starts from a different zero point, making UK sizes generally 0.5 smaller than equivalent US men's sizes.

European sizes use Paris Points (⅔ cm each), measured from the insole length of the shoe — not the foot — which means the same EU size fits a range of foot lengths depending on how much toe room the shoe is designed to have. The CM/JP system used in Japan and increasingly by global athletic brands is the most straightforward: it directly represents the foot length in centimeters the shoe is designed to accommodate. If you know your foot length precisely, CM sizing eliminates conversion guesswork entirely and is the most reliable system for online purchasing across international brands.

Even within a single sizing system, the same nominal size from two different brands can fit very differently. The reason is the last — the 3D mold around which the shoe is constructed. A Nike running shoe last is engineered for a performance fit with a narrow heel, a slightly elevated instep, and a snug toe box that locks the foot during lateral movements. New Balance builds on a wider last with more volume through the forefoot, which is why runners with wider feet often find New Balance sizes feel more accurate than others.

European dress shoe brands like Salvatore Ferragamo or Magnanni use lasts designed for narrow Mediterranean foot profiles, so American buyers often need a half or full size up. Conversely, some Japanese brands size conservatively and run large. Even within a single brand, different shoe models can use different lasts — a company's trail runner and its road racing flat may fit quite differently at the same size. This is why the confidence score in the brand comparison feature matters: it reflects how well the two brands' sizing curves align for your specific size range, not just a generic offset.

Foot measurements change throughout the day. Your feet are at their smallest first thing in the morning and at their largest in the late afternoon after standing and walking, when they have expanded from swelling and weight bearing. Always measure at the end of the day, wearing the socks you plan to use with the shoes, to capture the maximum size you'll need to accommodate.

To measure at home, stand on a flat hard floor with your full weight on both feet — not sitting. Place a piece of paper against a wall, step on it with your heel touching the wall, and trace your foot outline with a pencil held perpendicular to the floor (not angled in). Measure from the back of the heel trace to the tip of the longest toe (which is not always the big toe — for many people it is the second toe). Measure both feet; most people have one foot slightly larger, and you should fit to the larger one. Centimeters give the most universally translatable result for cross-system conversions.

Online shoe shopping has the highest return rate of any clothing category — about 25–35% of orders are returned, with incorrect size being the leading reason. A few habits dramatically reduce that rate. First, always look up the brand's specific size chart rather than relying on a generic conversion table — brands publish insole measurements for each size, and comparing that to your foot length is the most reliable approach.

Second, read user reviews specifically for comments about fit, not just comfort or durability. If multiple reviewers say "runs a half size small" or "narrow in the toe box," that's more reliable than any size chart. Third, if you're between sizes, generally go up for athletic shoes and down for leather dress shoes (which will stretch). Fourth, for athletic shoes, ensure there is roughly a thumb's width (about 1 cm) between your longest toe and the end of the shoe — this prevents bruised toenails on downhills and swelling-related discomfort on long runs. Buying from retailers with free returns provides a safety net, but getting the size right the first time saves significant time.

Most shoe buyers focus entirely on length and ignore width, but width fit matters just as much for long-term foot health. The standard width system runs from AAA (extra narrow) through B (standard women's), D (standard men's), EE (wide), and up to EEEE (extra wide). Each letter step changes the ball-of-foot width by approximately 4.8 mm (3/16 inch), which is enough to cause blisters, bunions, or pressure sores if you're consistently wearing the wrong width.

Signs you need a wider shoe: your toes feel squeezed laterally, you develop calluses on the outer edge of your little toe, or you notice the upper leather bulging over the sole edge when wearing your shoes. Signs you need a narrower shoe: your foot slides laterally inside the shoe when turning, causing friction blisters on the inside of the heel or little toe. Only a handful of brands — New Balance, Brooks, Asics, and New Balance being the leaders — offer the full AAA through EEEE width range in most styles. If you need a non-standard width, filter by brand before selecting a model to avoid finding the right size is unavailable in your width.