{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"paper-size"},"result":{"entity_type":"calculator","id":"paper-size","calculator_id":"paper-size","canonical_url":"https://tttkmbb.com/conversion/paper-size","name":"Paper Size Converter","title":"Paper Size Converter – ISO 216 A/B, ISO 269 C/DL and US Letter/Legal/Tabloid Sizes in mm, Inches, Area and Aspect Ratio","category":"conversion","category_name":"Unit Conversion","tool_name":"convert_paper_size","featured_mcp_tool":false,"description":"Returns the dimensions of a standard paper size (ISO A0–A10, B0–B10, C4–C6, DL, US Letter, Legal, Tabloid, Executive, Statement, ANSI C–E) in millimetres and inches with area and aspect ratio, or finds the nearest standard size for given dimensions.","use_when":"You need the exact size of a paper format, the inch equivalent of an A or B size (or vice versa), the area for paper-weight calculations, or want to identify a sheet you measured.","do_not_use_when":"You need envelope fit for a folded sheet, printer margins, or photo/print sizes such as 4 × 6 in (use aspect-ratio for image proportions).","inputs":[{"name":"size","label":"Paper size","type":"enum","required":true,"values":[{"value":"a0","label":"A0 (ISO 216)","aliases":["din a0","iso a0"]},{"value":"a1","label":"A1 (ISO 216)","aliases":["din a1","iso a1"]},{"value":"a2","label":"A2 (ISO 216)","aliases":["din a2","iso a2"]},{"value":"a3","label":"A3 (ISO 216)","aliases":["din a3","iso a3"]},{"value":"a4","label":"A4 (ISO 216)","aliases":["din a4","iso a4"]},{"value":"a5","label":"A5 (ISO 216)","aliases":["din a5","iso a5"]},{"value":"a6","label":"A6 (ISO 216)","aliases":["din a6","iso a6"]},{"value":"a7","label":"A7 (ISO 216)","aliases":["din a7","iso a7"]},{"value":"a8","label":"A8 (ISO 216)","aliases":["din a8","iso a8"]},{"value":"a9","label":"A9 (ISO 216)","aliases":["din a9","iso a9"]},{"value":"a10","label":"A10 (ISO 216)","aliases":["din a10","iso a10"]},{"value":"b0","label":"B0 (ISO 216)","aliases":["iso b0"]},{"value":"b1","label":"B1 (ISO 216)","aliases":["iso b1"]},{"value":"b2","label":"B2 (ISO 216)","aliases":["iso b2"]},{"value":"b3","label":"B3 (ISO 216)","aliases":["iso b3"]},{"value":"b4","label":"B4 (ISO 216)","aliases":["iso b4"]},{"value":"b5","label":"B5 (ISO 216)","aliases":["iso b5"]},{"value":"b6","label":"B6 (ISO 216)","aliases":["iso b6"]},{"value":"b7","label":"B7 (ISO 216)","aliases":["iso b7"]},{"value":"b8","label":"B8 (ISO 216)","aliases":["iso b8"]},{"value":"b9","label":"B9 (ISO 216)","aliases":["iso b9"]},{"value":"b10","label":"B10 (ISO 216)","aliases":["iso b10"]},{"value":"c4","label":"C4 envelope (ISO 269)"},{"value":"c5","label":"C5 envelope (ISO 269)"},{"value":"c6","label":"C6 envelope (ISO 269)"},{"value":"dl","label":"DL envelope (110 × 220 mm)"},{"value":"letter","label":"US Letter / ANSI A (8.5 × 11 in)","aliases":["us letter","ansi a","a"]},{"value":"legal","label":"US Legal (8.5 × 14 in)","aliases":["us legal"]},{"value":"tabloid","label":"Tabloid / Ledger / ANSI B (11 × 17 in)","aliases":["ledger","ansi b","b"]},{"value":"executive","label":"Executive (7.25 × 10.5 in)"},{"value":"statement","label":"Statement / Half Letter (5.5 × 8.5 in)","aliases":["half letter","invoice"]},{"value":"ansi_c","label":"ANSI C (17 × 22 in)","aliases":["ansi c","c"]},{"value":"ansi_d","label":"ANSI D (22 × 34 in)","aliases":["ansi d","d"]},{"value":"ansi_e","label":"ANSI E (34 × 44 in)","aliases":["ansi e","e"]},{"value":"custom","label":"Custom dimensions (find the nearest standard size)","aliases":["nearest","measured"]}],"description":"Standard size to look up, or custom to identify a sheet from width and height.","example":"custom"},{"name":"width","label":"Width (custom only)","type":"number","required":false,"max":5000,"exclusive_min":0,"description":"Measured width in dimension_unit; used only with size=custom.","example":216},{"name":"height","label":"Height (custom only)","type":"number","required":false,"max":5000,"exclusive_min":0,"description":"Measured height in dimension_unit; used only with size=custom.","example":280},{"name":"dimension_unit","label":"Dimension unit","type":"enum","required":false,"default":"mm","values":[{"value":"mm","label":"Millimetres","aliases":["millimetre","millimeter","millimetres","millimeters"]},{"value":"in","label":"Inches","aliases":["inch","inches"]}],"description":"Unit of the custom width and height.","example":"mm"}],"outputs":[{"name":"size_name","label":"Size","type":"string","decimals":4,"description":"Name and family of the size (for custom input: the dimensions given)."},{"name":"width_mm","label":"Width","type":"number","unit":"mm","decimals":1,"description":"Short side in millimetres (portrait orientation)."},{"name":"height_mm","label":"Height","type":"number","unit":"mm","decimals":1,"description":"Long side in millimetres."},{"name":"width_in","label":"Width","type":"number","unit":"in","decimals":2,"description":"Short side in inches."},{"name":"height_in","label":"Height","type":"number","unit":"in","decimals":2,"description":"Long side in inches."},{"name":"area_m2","label":"Area","type":"number","unit":"m²","decimals":4,"description":"Sheet area in square metres (multiply by grammage in g/m² for the sheet weight)."},{"name":"area_in2","label":"Area","type":"number","unit":"in²","decimals":1,"description":"Sheet area in square inches."},{"name":"aspect_ratio","label":"Aspect ratio (long / short)","type":"number","decimals":4,"description":"Height divided by width; ISO sizes are √2 ≈ 1.4142."},{"name":"aspect_ratio_text","label":"Aspect ratio","type":"string","decimals":4,"description":"Ratio as 1 : x."},{"name":"nearest_standard_size","label":"Nearest standard size","type":"string","decimals":4,"description":"Closest standard size for custom dimensions (orientation ignored)."},{"name":"deviation_percent","label":"Deviation from nearest size","type":"number","unit":"%","decimals":1,"description":"Largest relative difference of the two sides from the nearest standard size (custom input only)."},{"name":"series_note","label":"Series note","type":"string","decimals":4,"description":"How the size relates to its family (halving, area, next sizes)."}],"input_schema":{"type":"object","properties":{"size":{"description":"Standard size to look up, or custom to identify a sheet from width and height.","type":"string","enum":["a0","a1","a2","a3","a4","a5","a6","a7","a8","a9","a10","b0","b1","b2","b3","b4","b5","b6","b7","b8","b9","b10","c4","c5","c6","dl","letter","legal","tabloid","executive","statement","ansi_c","ansi_d","ansi_e","custom"],"examples":["custom"]},"width":{"description":"Measured width in dimension_unit; used only with size=custom.","type":"number","maximum":5000,"exclusiveMinimum":0,"examples":[216]},"height":{"description":"Measured height in dimension_unit; used only with size=custom.","type":"number","maximum":5000,"exclusiveMinimum":0,"examples":[280]},"dimension_unit":{"description":"Unit of the custom width and height.","type":"string","enum":["mm","in"],"default":"mm","examples":["mm"]}},"additionalProperties":false,"required":["size"]},"output_schema":{"type":"object","properties":{"size_name":{"description":"Name and family of the size (for custom input: the dimensions given).","type":"string"},"width_mm":{"description":"Short side in millimetres (portrait orientation). Unit: mm.","type":"number","x-unit":"mm"},"height_mm":{"description":"Long side in millimetres. Unit: mm.","type":"number","x-unit":"mm"},"width_in":{"description":"Short side in inches. Unit: in.","type":"number","x-unit":"in"},"height_in":{"description":"Long side in inches. Unit: in.","type":"number","x-unit":"in"},"area_m2":{"description":"Sheet area in square metres (multiply by grammage in g/m² for the sheet weight). Unit: m².","type":"number","x-unit":"m²"},"area_in2":{"description":"Sheet area in square inches. Unit: in².","type":"number","x-unit":"in²"},"aspect_ratio":{"description":"Height divided by width; ISO sizes are √2 ≈ 1.4142.","type":"number"},"aspect_ratio_text":{"description":"Ratio as 1 : x.","type":"string"},"nearest_standard_size":{"description":"Closest standard size for custom dimensions (orientation ignored).","type":"string"},"deviation_percent":{"description":"Largest relative difference of the two sides from the nearest standard size (custom input only). Unit: %.","type":"number","x-unit":"%"},"series_note":{"description":"How the size relates to its family (halving, area, next sizes).","type":"string"}}},"formula":"ISO 216: A0 = 841 × 1189 mm (area ≈ 1 m²), each next size = previous long side halved, aspect √2; B(n) sides = geometric mean of A(n) and A(n−1); C(n) = geometric mean of A(n) and B(n); 1 in = 25.4 mm; area = width × height; aspect = height / width; nearest size = min over sizes of max(|w − w₀|/w₀, |h − h₀|/h₀)","method":"ISO dimensions are the standard's rounded millimetre values (tolerance ±1.5 mm for sizes up to 150 mm, ±2 mm up to 600 mm, ±3 mm above). US sizes follow ANSI/ASME Y14.1 and the customary Letter/Legal definitions.","sources":[{"name":"ISO 216:2007 – Writing paper and certain classes of printed matter – Trimmed sizes – A and B series","url":"https://www.iso.org/standard/36631.html","type":"standard","retrieved_at":"2026-09-24"},{"name":"Wikipedia – ISO 216","url":"https://en.wikipedia.org/wiki/ISO_216","type":"reference","retrieved_at":"2026-09-24"},{"name":"Wikipedia – Paper size (North American sizes, ANSI/ASME Y14.1)","url":"https://en.wikipedia.org/wiki/Paper_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":"A4","inputs":{"size":"a4"},"expected":{"width_mm":210,"height_mm":297,"width_in":8.27,"height_in":11.69,"area_m2":0.0624,"area_in2":96.7,"aspect_ratio":1.4143,"size_name":"A4 (ISO 216)"},"url":"https://tttkmbb.com/api/v1/calculate/paper-size?size=a4"},{"name":"US Letter","inputs":{"size":"letter"},"expected":{"width_mm":215.9,"height_mm":279.4,"width_in":8.5,"height_in":11,"area_m2":0.0603,"area_in2":93.5,"aspect_ratio":1.2941},"url":"https://tttkmbb.com/api/v1/calculate/paper-size?size=letter"}],"faq":[{"q":"Why is A4 not exactly 1/16 m²?","a":"Dimensions are rounded to whole millimetres at every halving step; A4 is 210 × 297 = 0.06237 m² instead of 0.0625 m², and its ratio 1.4143 differs from √2 in the fourth decimal."},{"q":"Is A4 the same as Letter?","a":"No. A4 is 6 mm narrower and 18 mm taller than US Letter (210 × 297 vs 215.9 × 279.4 mm); documents laid out for one usually need scaling (about 94 %) to print on the other."},{"q":"Which envelope fits an A4 sheet?","a":"C4 unfolded, C5 folded once, DL or C6/5 folded in thirds; C6 takes an A6 card or A4 folded twice."}],"tags":["paper size","a4 in inches","a4 dimensions mm","letter vs a4","iso 216","paper size converter"],"related":[{"calculator_id":"aspect-ratio","reason":"Aspect ratios of images and screens."},{"calculator_id":"area","reason":"Convert the sheet area between units."},{"calculator_id":"length","reason":"Convert individual dimensions between mm and inches."}],"links":{"html":"https://tttkmbb.com/conversion/paper-size","markdown":"https://tttkmbb.com/conversion/paper-size.md","json":"https://tttkmbb.com/conversion/paper-size.json","api":"https://tttkmbb.com/api/v1/calculate/paper-size","schema":"https://tttkmbb.com/api/v1/calculators/paper-size","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T01:46:41Z","next_actions":[{"tool":"run_calculator","calculator_id":"paper-size","reason":"Run Paper Size Converter with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/conversion/paper-size.md"}}