Converting height between systems
Height conversion runs on one exact figure: 1 inch equals precisely 2.54 centimetres, by international definition. Everything else follows from there — 1 foot is 12 inches (30.48 cm), and 1 metre is 100 cm. Because feet-and-inches is a mixed-radix system (whole feet, then a remainder in inches), converting from centimetres usually means dividing by 30.48 to get feet, then converting the remainder to inches — which this calculator handles automatically rather than leaving you with an ugly decimal like "5.74 feet."
Predicting a child's adult height
The mid-parental height method is a decades-old clinical rule of thumb pediatricians still use as a rough starting point, based on nothing more than both parents' heights:
Boys: (Father's height + Mother's height + 13 cm) ÷ 2
Girls: (Father's height + Mother's height − 13 cm) ÷ 2
Worked example: a father at 180 cm and mother at 165 cm gives a son an estimated (180 + 165 + 13) ÷ 2 = 179 cm, and a daughter an estimated (180 + 165 − 13) ÷ 2 = 166 cm.
The 13 cm adjustment approximates the average height gap between adult men and women, letting the same base formula apply to either sex. This is a population-level average, not a genetic calculation — real children commonly land several centimetres away from the estimate in either direction, since nutrition, health, and individual genetics all play a role that a two-input formula can't capture.
How the percentile estimate works — and its limits
Percentile mode compares a height against an average for the same gender, using a standard z-score: how many standard deviations above or below average the height sits, converted into "taller than X% of people."
Worth being upfront about: this calculator uses simplified adult average-height benchmarks (around 175 cm for men, 163 cm for women) rather than the detailed, age-by-month growth charts a pediatrician uses for children. That makes it a reasonable rough estimate for adults, but not a substitute for an actual clinical growth chart when tracking a child's development — a doctor's chart accounts for the rapid, uneven pace of childhood growth in a way a single average number can't.
Getting an accurate measurement in the first place
Stand fully upright against a flat wall with shoes off, heels together and touching the wall, and look straight ahead rather than tilting your chin up or down. Have someone place a flat, rigid object (a book works) level on top of your head and mark the wall where it touches, then measure from the floor to that mark with a tape measure. Measuring first thing in the morning gives a slightly taller reading than at night, since spinal discs compress a little over the course of a day — for consistency, measure at the same time of day if you're tracking change.
Related tools
Height is often tracked alongside weight for health and fitness purposes — the Weight Calculator handles unit conversion on that side the same way this page does for height.