Height Calculator

The most common method is the mid-parental height formula: add the mother's and father's heights, add 13 cm (5 in) for a boy or subtract 13 cm for a girl, then divide by 2. For example, a dad of 5'10" and mom of 5'5" give a predicted adult height of about 5'10" for a son and 5'5" for a daughter. Most predictions land within about 4 inches (10 cm) of the child's true adult height. A second method estimates height from the percentage of adult height a child has typically reached by their current age.

Using the mid-parental formula: 5'10" (177.8 cm) + 5'5" (165.1 cm) = 342.9 cm. For a son, add 13 cm and divide by 2 → about 178 cm (5'10"). For a daughter, subtract 13 cm and divide by 2 → about 165 cm (5'5"). Expect a range of roughly ±10 cm (±4 in) around that estimate, since genetics, nutrition, and timing of puberty all shift the final result.

The age-percentage method estimates that a boy has reached roughly 84% of his adult height by age 12. A 5'4" (162.6 cm) 12-year-old boy would project to about 6'0"–6'4" as an adult by this method — but boys who are tall early often finish nearer the average, so treat this as an upper-ish estimate. The mid-parental method (based on the parents' heights) is usually more reliable for a specific family.

For girls, height at about 18 months to 2 years, and for boys around age 2 to 2.5, is often cited as roughly half of eventual adult height — the classic 'double it' rule. It is a rough guide only. A toddler's growth channel (their percentile on the growth chart) tends to be a better predictor than a single measurement, and this calculator's age-percentage method uses that idea across all ages.

Girls typically reach about 97-98% of adult height by age 14, since female puberty growth spurts happen earlier than for boys. A 14-year-old girl at 5'4" (162.6 cm) would project to roughly 5'4"–5'6" as an adult by the age-percentage method — only a small amount of growth is usually left. Boys grow for longer, so the same current height and age would predict differently for a son than a daughter.

Most girls reach their adult height by age 14-15, once growth plates in the long bones fuse after puberty. Most boys keep growing a bit longer, typically until 16-18, sometimes into the early 20s for a small final growth spurt. Growth plates fusing is what actually ends height increase — you can check this with an X-ray, but for a quick estimate, our calculator's age-percentage method accounts for the different timelines for boys and girls.

Height predictors are estimates, not guarantees. The mid-parental method is usually accurate within about 4 inches (10 cm) for most children. Actual adult height depends on genetics beyond the parents, nutrition, overall health, sleep, and the timing of puberty. Children with early or late puberty, growth conditions, or hormonal issues can fall well outside the predicted range. For any medical concern about growth, consult a pediatrician.