How it works
The mid-parental formula averages both parents and shifts 13 cm up for boys or down for girls. The ±8.5 cm band covers where most children land; genes, nutrition and health move individuals inside or outside it.
175 + 162 → boy about 175 cm (167–183)
Tips
- Measure in the morning barefoot for the truest numbers.
- Growth charts at check-ups beat any formula for tracking a real child.
- Everything runs in your browser; nothing is uploaded.
Standards and sources
- Tanner JM et al. (1970), Standards for children's height allowing for height of parents — Arch Dis Child (PMC, NIH)
- Ciancia S et al. (2025), How accurate is Tanner's formula in estimating target height? — BMC Pediatrics (PMC, NIH)
Last reviewed October 13, 2026
Frequently asked questions
How is it calculated?
The mid-parental formula: (father + mother ± 13) ÷ 2 — plus for boys, minus for girls — with a ±8.5 cm range covering most children.
How accurate is it?
About right for most families, but genes, nutrition and health move individuals outside the range. It is guidance, not a promise.
Which units?
Centimetres. Convert feet and inches first (1 ft = 30.48 cm).