{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"shoe-size"},"result":{"entity_type":"calculator","id":"shoe-size","calculator_id":"shoe-size","canonical_url":"https://tttkmbb.com/everyday/shoe-size","name":"Shoe Size Converter","title":"Shoe Size Converter – US Men's, US Women's, UK, EU and Centimetre (Japan) Adult Sizes","category":"everyday","category_name":"Everyday Life","tool_name":"convert_shoe_size","featured_mcp_tool":false,"description":"Converts an adult shoe size between US men's, US women's, UK, EU (Paris point) and centimetre foot-length (Japanese / Mondopoint) sizing with the adult formulas of the Wikipedia 'Shoe size' article, snapping to the nearest half UK size of the adult chart (UK 3–14).","use_when":"You have a shoe size in one system, or a measured foot length in centimetres, and need the equivalent adult US, UK, EU or centimetre size.","do_not_use_when":"You need children's sizes (different scales), width fittings, or an exact match for a specific brand — brand charts differ by up to a full size, so use the brand's own table; to convert foot lengths between units use length.","inputs":[{"name":"size","label":"Size","type":"number","required":true,"min":0,"max":60,"description":"The size number in the chosen system (for cm: the measured foot length in centimetres).","example":10},{"name":"system","label":"Sizing system","type":"enum","required":true,"values":[{"value":"us_men","label":"US men's","aliases":["us","us_m","usa_men","men"]},{"value":"us_women","label":"US women's","aliases":["us_w","usa_women","women"]},{"value":"uk","label":"UK / Ireland","aliases":["british","ireland","gb"]},{"value":"eu","label":"EU (Paris point)","aliases":["eur","europe","european","fr","de","it","es"]},{"value":"cm","label":"Centimetres – foot length (Japan / Mondopoint)","aliases":["jp","japan","japanese","mondopoint","centimeters","centimetres"]}],"description":"System of the entered size.","example":"us_men"}],"outputs":[{"name":"us_men","label":"US men's","type":"number","decimals":1,"description":"US men's size = UK + 1."},{"name":"us_women","label":"US women's","type":"number","decimals":1,"description":"US women's size = US men's + 1.5 (common retail scale; athletic/FIA charts use +1)."},{"name":"uk","label":"UK","type":"number","decimals":1,"description":"UK size, the nearest half size of the adult chart (3–14)."},{"name":"eu","label":"EU","type":"number","decimals":1,"description":"EU (Paris point) size = 1.5 × foot length in cm + 2, rounded to the nearest half size."},{"name":"cm","label":"Foot length","type":"number","unit":"cm","decimals":1,"description":"Foot length of the chart row, (UK + 23) / 3 inches in cm; the basis of Japanese and Mondopoint sizing."},{"name":"jp","label":"Japan","type":"number","unit":"cm","decimals":1,"description":"Japanese (JIS) size = foot length in cm rounded to the nearest 0.5."},{"name":"foot_length_in","label":"Foot length","type":"number","unit":"in","decimals":2,"description":"Foot length of the chart row in inches."},{"name":"note","label":"Note","type":"string","decimals":4,"description":"Chart row used and the brand-variation caveat."}],"input_schema":{"type":"object","properties":{"size":{"description":"The size number in the chosen system (for cm: the measured foot length in centimetres).","type":"number","minimum":0,"maximum":60,"examples":[10]},"system":{"description":"System of the entered size.","type":"string","enum":["us_men","us_women","uk","eu","cm"],"examples":["us_men"]}},"additionalProperties":false,"required":["size","system"]},"output_schema":{"type":"object","properties":{"us_men":{"description":"US men's size = UK + 1.","type":"number"},"us_women":{"description":"US women's size = US men's + 1.5 (common retail scale; athletic/FIA charts use +1).","type":"number"},"uk":{"description":"UK size, the nearest half size of the adult chart (3–14).","type":"number"},"eu":{"description":"EU (Paris point) size = 1.5 × foot length in cm + 2, rounded to the nearest half size.","type":"number"},"cm":{"description":"Foot length of the chart row, (UK + 23) / 3 inches in cm; the basis of Japanese and Mondopoint sizing. Unit: cm.","type":"number","x-unit":"cm"},"jp":{"description":"Japanese (JIS) size = foot length in cm rounded to the nearest 0.5. Unit: cm.","type":"number","x-unit":"cm"},"foot_length_in":{"description":"Foot length of the chart row in inches. Unit: in.","type":"number","x-unit":"in"},"note":{"description":"Chart row used and the brand-variation caveat.","type":"string"}}},"formula":"foot_in = (UK + 23) / 3 = (US_men + 22) / 3 = (US_women + 20.5) / 3; cm = foot_in × 2.54 = (EU − 2) / 1.5; UK = 3 × foot_in − 23 rounded to the nearest 0.5 (chart UK 3–14); US_men = UK + 1; US_women = US_men + 1.5; EU = 1.5 × cm + 2 rounded to the nearest 0.5; JP = cm rounded to the nearest 0.5","method":"Adult formulas from the Wikipedia 'Shoe size' article: the UK/US barleycorn scale (1/3 inch per size, US men's one size above UK) and the EU Paris point (2/3 cm per size, including the 2-point last allowance). The result is the chart row nearest to the input, so converting back and forth can move by half a size; manufacturers' charts deviate by up to one full size and their cm/Japanese labels typically run 0.5–1 cm larger than the measured foot.","sources":[{"name":"Shoe size – sizing systems and adult conversion formulas (Wikipedia)","url":"https://en.wikipedia.org/wiki/Shoe_size","type":"reference","retrieved_at":"2026-09-24"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"US men's 10","inputs":{"size":10,"system":"us_men"},"expected":{"us_men":10,"us_women":11.5,"uk":9,"eu":42.5,"cm":27.1,"jp":27,"foot_length_in":10.67},"url":"https://tttkmbb.com/api/v1/calculate/shoe-size?size=10&system=us_men"},{"name":"24 cm foot length","inputs":{"size":24,"system":"cm"},"expected":{"uk":5.5,"us_men":6.5,"us_women":8,"eu":38,"cm":24.1,"jp":24},"url":"https://tttkmbb.com/api/v1/calculate/shoe-size?size=24&system=cm"}],"faq":[{"q":"Why does my brand's chart give a different EU or cm size?","a":"Brands size on their own lasts: EU labels vary by about ±1 and cm/Japanese labels usually include 0.5–1 cm of toe room beyond the measured foot. This tool applies the published formula relations, so treat the result as a starting point."},{"q":"Which US women's scale is used?","a":"The common retail scale (women's = men's + 1.5). Athletic brands using the FIA scale label women's shoes only one size above men's; subtract 0.5 for those."},{"q":"How do I measure foot length?","a":"Stand on paper, mark the heel and the longest toe, measure the distance in cm and use the larger foot; enter it with system cm."}],"tags":["shoe size converter","us to eu shoe size","uk to us shoe size","shoe size in cm","foot length to shoe size"],"related":[{"calculator_id":"ring-size","reason":"Ring sizes between US, UK, EU, Japan and millimetres."},{"calculator_id":"length","reason":"Convert foot length between centimetres and inches."}],"links":{"html":"https://tttkmbb.com/everyday/shoe-size","markdown":"https://tttkmbb.com/everyday/shoe-size.md","json":"https://tttkmbb.com/everyday/shoe-size.json","api":"https://tttkmbb.com/api/v1/calculate/shoe-size","schema":"https://tttkmbb.com/api/v1/calculators/shoe-size","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T03:45:08Z"}