{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"vitamin-iu-conversion"},"result":{"entity_type":"calculator","id":"vitamin-iu-conversion","calculator_id":"vitamin-iu-conversion","canonical_url":"https://tttkmbb.com/medical/vitamin-iu-conversion","name":"Vitamin IU Converter","title":"Vitamin IU to Microgram/Milligram Converter – Vitamin D, Vitamin A (Retinol) and Vitamin E","category":"medical","category_name":"Medical & Clinical","tool_name":"convert_vitamin_iu","featured_mcp_tool":false,"description":"Converts international units to mass and back for vitamin D (1 µg = 40 IU), vitamin A as retinol (1 IU = 0.3 µg) and vitamin E as natural d-alpha-tocopherol (1 IU = 0.67 mg) or synthetic dl-alpha-tocopherol (1 IU = 0.9 mg by mass, 0.45 mg alpha-tocopherol equivalents for RDA purposes).","use_when":"A supplement label, prescription or dietary reference gives a vitamin in IU and you need µg or mg, or vice versa.","do_not_use_when":"The vitamin is not D, A or E (IU is not defined for others in current use), or the vitamin A source is beta-carotene, which has different retinol-activity factors.","inputs":[{"name":"vitamin","label":"Vitamin","type":"enum","required":true,"values":[{"value":"vitamin_d","label":"Vitamin D (D2 or D3): 1 µg = 40 IU","aliases":["d","d3","d2","cholecalciferol","ergocalciferol"]},{"value":"vitamin_a_retinol","label":"Vitamin A as retinol: 1 IU = 0.3 µg","aliases":["a","retinol","vitamin_a"]},{"value":"vitamin_e_natural","label":"Vitamin E, natural d-alpha-tocopherol (RRR): 1 IU = 0.67 mg","aliases":["e","d-alpha","vitamin_e","rrr"]},{"value":"vitamin_e_synthetic","label":"Vitamin E, synthetic dl-alpha-tocopherol (all-rac), USP mass: 1 IU = 0.9 mg","aliases":["dl-alpha","all-rac"]},{"value":"vitamin_e_synthetic_iom","label":"Vitamin E, synthetic, IOM/FDA bioactivity: 1 IU = 0.45 mg alpha-tocopherol","aliases":["synthetic_iom","all-rac-iom"]}],"description":"Vitamin and form; the conversion factor differs by form.","example":"vitamin_d"},{"name":"direction","label":"Direction","type":"enum","required":false,"default":"iu_to_mass","values":[{"value":"iu_to_mass","label":"IU → mass","aliases":["iu","to_mass"]},{"value":"mass_to_iu","label":"Mass → IU","aliases":["mass","to_iu"]}],"description":"Whether the value is in IU or in mass units.","example":"iu_to_mass"},{"name":"value","label":"Value","type":"number","required":true,"max":1000000000,"exclusive_min":0,"description":"Amount in IU (iu_to_mass) or in mass_unit (mass_to_iu).","example":1000},{"name":"mass_unit","label":"Mass unit (for mass_to_iu)","type":"enum","required":false,"default":"ug","values":[{"value":"ug","label":"µg (mcg)","aliases":["µg","mcg","microgram","micrograms"]},{"value":"mg","label":"mg","aliases":["milligram","milligrams"]}],"description":"Unit of the value when direction is mass_to_iu; ignored otherwise.","example":"ug"}],"outputs":[{"name":"iu","label":"International units","type":"number","unit":"IU","decimals":2,"description":"Amount in IU."},{"name":"micrograms","label":"Mass","type":"number","unit":"µg","decimals":3,"description":"Amount in micrograms."},{"name":"milligrams","label":"Mass","type":"number","unit":"mg","decimals":4,"description":"Amount in milligrams."},{"name":"factor_note","label":"Factor used","type":"string","decimals":4,"description":"The published conversion applied."}],"input_schema":{"type":"object","properties":{"vitamin":{"description":"Vitamin and form; the conversion factor differs by form.","type":"string","enum":["vitamin_d","vitamin_a_retinol","vitamin_e_natural","vitamin_e_synthetic","vitamin_e_synthetic_iom"],"examples":["vitamin_d"]},"direction":{"description":"Whether the value is in IU or in mass units.","type":"string","enum":["iu_to_mass","mass_to_iu"],"default":"iu_to_mass","examples":["iu_to_mass"]},"value":{"description":"Amount in IU (iu_to_mass) or in mass_unit (mass_to_iu).","type":"number","maximum":1000000000,"exclusiveMinimum":0,"examples":[1000]},"mass_unit":{"description":"Unit of the value when direction is mass_to_iu; ignored otherwise.","type":"string","enum":["ug","mg"],"default":"ug","examples":["ug"]}},"additionalProperties":false,"required":["vitamin","value"]},"output_schema":{"type":"object","properties":{"iu":{"description":"Amount in IU. 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Results are informational only and not a substitute for clinical judgement or medical advice.","sources":[{"name":"NIH Office of Dietary Supplements – Vitamin D fact sheet for health professionals","url":"https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/","type":"government","retrieved_at":"2026-09-24"},{"name":"NIH Office of Dietary Supplements – Vitamin E fact sheet for health professionals","url":"https://ods.od.nih.gov/factsheets/VitaminE-HealthProfessional/","type":"government","retrieved_at":"2026-09-24"},{"name":"NIH Office of Dietary Supplements – Vitamin A and carotenoids fact sheet for health professionals","url":"https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/","type":"government","retrieved_at":"2026-09-24"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. 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