{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"child-height-predictor"},"result":{"entity_type":"calculator","id":"child-height-predictor","calculator_id":"child-height-predictor","canonical_url":"https://tttkmbb.com/health/child-height-predictor","name":"Child Height Predictor","title":"Child Height Predictor – Adult Height from Parents' Heights (Mid-Parental Method)","category":"health","category_name":"Health","tool_name":"predict_adult_height","featured_mcp_tool":false,"description":"Predicts a child's adult height from the parents' heights with the sex-adjusted mid-parental (target) height method of Tanner, Goldstein and Whitehouse (1970): boys (mother + father + 13 cm) / 2, girls (mother + father − 13 cm) / 2, with a ± 8.5 cm target range.","use_when":"You want a genetic-potential estimate of a child's adult height from the parents' heights, or the target range against which a child's growth is judged.","do_not_use_when":"You need a prediction that uses the child's own current height, bone age or growth percentile (use growth charts or the Khamis-Roche method); the estimate is informational only, not medical advice.","inputs":[{"name":"mother_height_cm","label":"Mother's height","type":"number","unit":"cm","required":true,"min":120,"max":220,"description":"Biological mother's adult height in centimetres.","example":165},{"name":"father_height_cm","label":"Father's height","type":"number","unit":"cm","required":true,"min":120,"max":230,"description":"Biological father's adult height in centimetres.","example":180},{"name":"sex","label":"Biological sex","type":"enum","required":true,"values":[{"value":"male","label":"Male","aliases":["m","man"]},{"value":"female","label":"Female","aliases":["f","woman"]}],"description":"Sex of the child: boys add 13 cm, girls subtract 13 cm (the average adult male–female height difference) before halving.","example":"male"}],"outputs":[{"name":"predicted_height_cm","label":"Predicted adult height","type":"number","unit":"cm","decimals":1,"description":"Sex-adjusted mid-parental (target) height."},{"name":"range_low_cm","label":"Target range (low)","type":"number","unit":"cm","decimals":1,"description":"predicted_height_cm − 8.5 cm."},{"name":"range_high_cm","label":"Target range (high)","type":"number","unit":"cm","decimals":1,"description":"predicted_height_cm + 8.5 cm."},{"name":"predicted_height_ft_in","label":"Predicted adult height (ft/in)","type":"string","decimals":4,"description":"The prediction in feet and inches, e.g. '5 ft 10.5 in'."},{"name":"method_note","label":"Method note","type":"string","decimals":4,"description":"Which formula was applied and what the range means."}],"input_schema":{"type":"object","properties":{"mother_height_cm":{"description":"Biological mother's adult height in centimetres. Unit: cm.","type":"number","minimum":120,"maximum":220,"examples":[165],"x-unit":"cm"},"father_height_cm":{"description":"Biological father's adult height in centimetres. Unit: cm.","type":"number","minimum":120,"maximum":230,"examples":[180],"x-unit":"cm"},"sex":{"description":"Sex of the child: boys add 13 cm, girls subtract 13 cm (the average adult male–female height difference) before halving.","type":"string","enum":["male","female"],"examples":["male"]}},"additionalProperties":false,"required":["mother_height_cm","father_height_cm","sex"]},"output_schema":{"type":"object","properties":{"predicted_height_cm":{"description":"Sex-adjusted mid-parental (target) height. Unit: cm.","type":"number","x-unit":"cm"},"range_low_cm":{"description":"predicted_height_cm − 8.5 cm. Unit: cm.","type":"number","x-unit":"cm"},"range_high_cm":{"description":"predicted_height_cm + 8.5 cm. Unit: cm.","type":"number","x-unit":"cm"},"predicted_height_ft_in":{"description":"The prediction in feet and inches, e.g. '5 ft 10.5 in'.","type":"string"},"method_note":{"description":"Which formula was applied and what the range means.","type":"string"}}},"formula":"boys: predicted_height_cm = (mother_height_cm + father_height_cm + 13) / 2; girls: predicted_height_cm = (mother_height_cm + father_height_cm − 13) / 2; range_low_cm = predicted − 8.5; range_high_cm = predicted + 8.5","method":"The 13 cm adjustment is the average adult height difference between men and women; the ± 8.5 cm range (about two standard deviations) contains roughly 95 % of the adult heights of children of the same parents. Nutrition, illness, puberty timing and measurement error are not modelled. Informational only, not medical advice.","sources":[{"name":"Tanner JM, Goldstein H, Whitehouse RH (1970) Standards for children's height at ages 2–9 years allowing for height of parents, Arch Dis Child 45:755-762","url":"https://adc.bmj.com/content/45/244/755","type":"peer_reviewed","retrieved_at":"2026-09-24"},{"name":"Wikipedia – Human height (predicting adult height)","url":"https://en.wikipedia.org/wiki/Human_height","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":"Boy, mother 165 cm, father 180 cm","inputs":{"mother_height_cm":165,"father_height_cm":180,"sex":"male"},"expected":{"predicted_height_cm":179,"range_low_cm":170.5,"range_high_cm":187.5,"predicted_height_ft_in":"5 ft 10.5 in"},"url":"https://tttkmbb.com/api/v1/calculate/child-height-predictor?mother_height_cm=165&father_height_cm=180&sex=male"},{"name":"Girl, mother 165 cm, father 180 cm","inputs":{"mother_height_cm":165,"father_height_cm":180,"sex":"female"},"expected":{"predicted_height_cm":166,"range_low_cm":157.5,"range_high_cm":174.5,"predicted_height_ft_in":"5 ft 5.4 in"},"url":"https://tttkmbb.com/api/v1/calculate/child-height-predictor?mother_height_cm=165&father_height_cm=180&sex=female"}],"faq":[{"q":"How accurate is the mid-parental height?","a":"About 95 % of children end up within ± 8.5 cm of the target, so a single prediction can easily be 5 cm off. Methods that use the child's current height and bone age (e.g. Khamis-Roche, Bayley-Pinneau) are more precise."},{"q":"Why 13 cm?","a":"Adult men are on average about 13 cm (5 in) taller than adult women, so the father's height is expressed on the female scale for girls and the mother's on the male scale for boys before averaging."}],"tags":["child height predictor","how tall will my child be","mid-parental height","target height","adult height prediction"],"related":[{"calculator_id":"bmi","reason":"Adult BMI from the predicted height and a weight."},{"calculator_id":"ideal-weight","reason":"Ideal-weight formulas for the predicted adult height."}],"links":{"html":"https://tttkmbb.com/health/child-height-predictor","markdown":"https://tttkmbb.com/health/child-height-predictor.md","json":"https://tttkmbb.com/health/child-height-predictor.json","api":"https://tttkmbb.com/api/v1/calculate/child-height-predictor","schema":"https://tttkmbb.com/api/v1/calculators/child-height-predictor","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T03:47:35Z","next_actions":[{"tool":"run_calculator","calculator_id":"child-height-predictor","reason":"Run Child Height Predictor with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/health/child-height-predictor.md"}}