{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"blood-volume"},"result":{"entity_type":"calculator","id":"blood-volume","calculator_id":"blood-volume","canonical_url":"https://tttkmbb.com/medical/blood-volume","name":"Blood Volume Calculator","title":"Blood Volume Calculator – Nadler Equation and Gilcher's Rule with Plasma and Red Cell Volume","category":"medical","category_name":"Medical & Clinical","tool_name":"estimate_blood_volume","featured_mcp_tool":false,"description":"Estimates total blood volume from sex, height and weight with the Nadler (1962) equation, or from weight and body build with Gilcher's rule of fives (mL/kg), and splits it into plasma and red cell volume when the haematocrit is given.","use_when":"You need an adult's estimated total blood volume (L, mL or mL/kg) or plasma volume, for example to express blood loss as a fraction of volume or to plan apheresis or plasma exchange.","do_not_use_when":"The person is a child or neonate (paediatric mL/kg norms differ), pregnant, or has extreme body composition; measured (isotope-dilution) volumes are needed for dosing decisions. Results are informational and not medical advice.","inputs":[{"name":"sex","label":"Sex","type":"enum","required":true,"values":[{"value":"male","label":"Male","aliases":["m","man"]},{"value":"female","label":"Female","aliases":["f","woman"]}],"description":"Sex used to select the formula coefficients or thresholds.","example":"male"},{"name":"height_cm","label":"Height","type":"number","unit":"cm","required":true,"min":100,"max":250,"description":"Height in centimetres (used by the Nadler equation).","example":180},{"name":"weight_kg","label":"Weight","type":"number","unit":"kg","required":true,"min":20,"max":400,"description":"Body weight in kilograms.","example":80},{"name":"method","label":"Method","type":"enum","required":false,"default":"nadler","values":[{"value":"nadler","label":"Nadler 1962 equation (height and weight)","aliases":["nadler_equation"]},{"value":"gilcher_rule","label":"Gilcher's rule of fives (mL/kg by build)","aliases":["gilcher","rule_of_fives","ml_per_kg"]}],"description":"Estimation method; Gilcher's rule uses weight and build only.","example":"nadler"},{"name":"build","label":"Body build (Gilcher)","type":"enum","required":false,"default":"normal","values":[{"value":"athletic","label":"Athletic / muscular (75 male, 70 female mL/kg)","aliases":["muscular"]},{"value":"normal","label":"Normal (70 male, 65 female mL/kg)","aliases":["average"]},{"value":"thin","label":"Thin (65 male, 60 female mL/kg)","aliases":["lean","slim"]},{"value":"obese","label":"Obese (60 male, 55 female mL/kg)"}],"description":"Body build used only by Gilcher's rule; ignored by Nadler.","example":"normal"},{"name":"hematocrit_percent","label":"Haematocrit","type":"number","unit":"%","required":false,"min":10,"max":70,"description":"Optional haematocrit in percent; enables plasma and red cell volume.","example":45}],"outputs":[{"name":"blood_volume_l","label":"Total blood volume","type":"number","unit":"L","decimals":3,"description":"Estimated total blood volume in litres."},{"name":"blood_volume_ml","label":"Total blood volume","type":"number","unit":"mL","decimals":0,"description":"Same volume in millilitres."},{"name":"ml_per_kg","label":"Blood volume per kg","type":"number","unit":"mL/kg","decimals":1,"description":"blood_volume_ml / weight_kg (adult norms about 60–75 mL/kg)."},{"name":"plasma_volume_ml","label":"Plasma volume","type":"number","unit":"mL","decimals":0,"description":"Blood volume × (1 − haematocrit); only when hematocrit_percent is given."},{"name":"red_cell_volume_ml","label":"Red cell volume","type":"number","unit":"mL","decimals":0,"description":"Blood volume × haematocrit; only when hematocrit_percent is given."},{"name":"method_used","label":"Method used","type":"string","decimals":4,"description":"Equation or factor applied."}],"input_schema":{"type":"object","properties":{"sex":{"description":"Sex used to select the formula coefficients or thresholds.","type":"string","enum":["male","female"],"examples":["male"]},"height_cm":{"description":"Height in centimetres (used by the Nadler equation). Unit: cm.","type":"number","minimum":100,"maximum":250,"examples":[180],"x-unit":"cm"},"weight_kg":{"description":"Body weight in kilograms. Unit: kg.","type":"number","minimum":20,"maximum":400,"examples":[80],"x-unit":"kg"},"method":{"description":"Estimation method; Gilcher's rule uses weight and build only.","type":"string","enum":["nadler","gilcher_rule"],"default":"nadler","examples":["nadler"]},"build":{"description":"Body build used only by Gilcher's rule; ignored by Nadler.","type":"string","enum":["athletic","normal","thin","obese"],"default":"normal","examples":["normal"]},"hematocrit_percent":{"description":"Optional haematocrit in percent; enables plasma and red cell volume. Unit: %.","type":"number","minimum":10,"maximum":70,"examples":[45],"x-unit":"%"}},"additionalProperties":false,"required":["sex","height_cm","weight_kg"]},"output_schema":{"type":"object","properties":{"blood_volume_l":{"description":"Estimated total blood volume in litres. Unit: L.","type":"number","x-unit":"L"},"blood_volume_ml":{"description":"Same volume in millilitres. Unit: mL.","type":"number","x-unit":"mL"},"ml_per_kg":{"description":"blood_volume_ml / weight_kg (adult norms about 60–75 mL/kg). Unit: mL/kg.","type":"number","x-unit":"mL/kg"},"plasma_volume_ml":{"description":"Blood volume × (1 − haematocrit); only when hematocrit_percent is given. Unit: mL.","type":"number","x-unit":"mL"},"red_cell_volume_ml":{"description":"Blood volume × haematocrit; only when hematocrit_percent is given. Unit: mL.","type":"number","x-unit":"mL"},"method_used":{"description":"Equation or factor applied.","type":"string"}}},"formula":"Nadler: BV (L) = 0.3669 × h³ + 0.03219 × weight_kg + 0.6041 (male) or 0.3561 × h³ + 0.03308 × weight_kg + 0.1833 (female), h = height_cm / 100 in metres. Gilcher: BV (mL) = weight_kg × factor, factor (mL/kg) male athletic 75 / normal 70 / thin 65 / obese 60, female 70 / 65 / 60 / 55. plasma_volume_ml = BV × (1 − hematocrit_percent / 100); red_cell_volume_ml = BV × hematocrit_percent / 100","method":"Nadler's regression was fitted to isotope-dilution measurements in healthy adults and is the equation built into apheresis instruments; Gilcher's rule is a bedside approximation. Both assume normal hydration and typically differ by up to about 10%. Results are informational only and not a substitute for clinical judgement or medical advice.","sources":[{"name":"Nadler SB, Hidalgo JU, Bloch T (1962) Prediction of blood volume in normal human adults, Surgery 51:224-232","url":"https://pubmed.ncbi.nlm.nih.gov/21936146/","type":"peer_reviewed","retrieved_at":"2026-09-24"},{"name":"Wikipedia – Blood volume (Nadler equation, Gilcher's rule of fives)","url":"https://en.wikipedia.org/wiki/Blood_volume","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":"Male, 180 cm, 80 kg, haematocrit 45% (Nadler)","inputs":{"sex":"male","height_cm":180,"weight_kg":80,"hematocrit_percent":45},"expected":{"blood_volume_l":5.319,"blood_volume_ml":5319,"ml_per_kg":66.5,"plasma_volume_ml":2925,"red_cell_volume_ml":2394},"url":"https://tttkmbb.com/api/v1/calculate/blood-volume?sex=male&height_cm=180&weight_kg=80&hematocrit_percent=45"},{"name":"Female, 165 cm, 60 kg (Nadler)","inputs":{"sex":"female","height_cm":165,"weight_kg":60,"method":"nadler"},"expected":{"blood_volume_l":3.768,"blood_volume_ml":3768,"ml_per_kg":62.8},"url":"https://tttkmbb.com/api/v1/calculate/blood-volume?sex=female&height_cm=165&weight_kg=60&method=nadler"}],"faq":[{"q":"Which method should I use?","a":"Nadler when height is known: it is the standard regression and what apheresis systems use. Gilcher's rule needs only weight and a build category and is a rounder estimate."},{"q":"Why is mL/kg lower in obesity?","a":"Adipose tissue is poorly vascularised, so blood volume rises more slowly than weight; Nadler captures this through the height term and Gilcher through the obese factor (60 / 55 mL/kg)."},{"q":"How is this used for blood loss?","a":"Haemorrhage classes are fractions of total volume: 15% of a 5.3 L volume is about 800 mL. The estimate does not account for pregnancy, dehydration or anaemia."}],"tags":["blood volume","nadler equation","total blood volume","plasma volume","gilcher rule","ml/kg"],"related":[{"calculator_id":"body-surface-area","reason":"Body surface area for BSA-based apheresis and chemotherapy calculations."},{"calculator_id":"adjusted-body-weight","reason":"Dosing weight for people well above ideal weight."},{"calculator_id":"parkland-formula","reason":"Fluid volumes for burn resuscitation."}],"links":{"html":"https://tttkmbb.com/medical/blood-volume","markdown":"https://tttkmbb.com/medical/blood-volume.md","json":"https://tttkmbb.com/medical/blood-volume.json","api":"https://tttkmbb.com/api/v1/calculate/blood-volume","schema":"https://tttkmbb.com/api/v1/calculators/blood-volume","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T03:48:09Z","next_actions":[{"tool":"run_calculator","calculator_id":"blood-volume","reason":"Run Blood Volume Calculator with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/medical/blood-volume.md"}}