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Calculator Answers

Height Calculator

Blake Boege
Written by Blake Boege · Founder, Calculator Answers

A height calculator is a dual-purpose measurement utility. It converts height values between imperial units (feet and inches) and metric units (centimeters and meters) to facilitate standard records. Additionally, it incorporates the mid-parental height method to project the estimated adult stature of a child based on the biological parents' heights and the child's gender. Pediatricians and parents use these projections to track developmental trajectories, while researchers use the conversion functions to standardize anthropometric data across different measurement systems.

Pick a mode. In convert mode, enter your height in any common unit and the calculator returns all the others. In mid-parental mode, enter the parents' heights to estimate the child's adult height.

See also: Ideal Weight Calculator, BMI Calculator, and Bench Press Calculator.

Quick Answer

Convert height measurements between units, or project a child's future adult height using the mid-parental height formula.

Mode

Unit

Disclaimer

The mid-parental height method (Tanner) is a rough estimate. Real adult height also depends on nutrition, health, and individual growth patterns. The estimate has a 95% range of roughly ±4 inches around the predicted value.

Educational tool. Not medical advice. For pediatric growth tracking and concerns, consult a pediatrician.

Height

Height

5 ft 10 in

177.8 cm; 1.778 m; 70 in

ft + in5 ft 10 in
Total inches70 in
Centimeters177.8 cm
Meters1.778 m

1 inch = 2.54 cm exactly. Mid-parental height formula: for boys (mother + father + 5 in) / 2; for girls (mother + father − 5 in) / 2.

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Examples

5 ft 10 in

= 70 in = 177.80 cm = 1.778 m

175 cm

≈ 5 ft 8.9 in = 68.90 in

Boy: mother 5 ft 4 in, father 6 ft 0 in

≈ 5 ft 10.5 in

Girl: mother 5 ft 6 in, father 5 ft 11 in

≈ 5 ft 4 in

How it works

Formula · adult height ≈ (mother + father ± 5 in) ÷ 2, shown with a 4 in band either side

Height conversion uses the exact conversion 1 in = 2.54 cm. Mid-parental height uses the standard Tanner formula with a 5-inch sex adjustment.

Boy · (mom + dad + 5 in) / 2

Girl · (mom + dad − 5 in) / 2

By hand, one line of arithmetic

As an adult height predictor this is about as simple as it gets: a single average with one adjustment.

The mid-parental method is a single average with one adjustment. A mother of 5 ft 5 in and a father of 5 ft 11 in, which is 65 and 71 inches.

  1. Add both parents' heights in inches. 65 + 71 = 136
  2. Add 5 inches for a boy, or subtract 5 for a girl. 136 + 5 = 141
  3. Halve it. 141 ÷ 2 = 70.5 in, which is 5 ft 10.5 in, or 179.1 cm.

Adding 5 then halving is the same as averaging then adding 2.5, which is how the rule is often written. Both give 70.5 here. For a girl the same parents give (136 − 5) ÷ 2 = 65.5 in.

The band around the number, and what it is not

The calculator shows 4 inches either side of the estimate. That is a wide band on purpose: it covers 8 inches in total, which for the example above runs from about 168.9 cm to 189.2 cm. Two children of the same parents can sit at opposite ends of it.

It is the spread conventionally quoted alongside this method, and this page presents it as the calculator's own working range rather than as a statistic. It cites no study for a confidence level, because it would rather show the band it actually uses than attach a number it cannot point at. Children land outside it regularly.

What this is not

  • Not a growth chart. A pediatric growth chart tracks a child against population percentiles over time, month by month. This takes two numbers and returns one. It cannot tell you whether a child is growing normally.
  • Not a bone age estimate. Skeletal maturity, read from a hand radiograph, is what a clinician uses to judge how much growing is left. Nothing here observes the child at all.
  • Not a diagnosis. A result far from what you expected is not a finding. If you have a concern about a child's growth, that is a conversation for a pediatrician, who has the chart, the history and the option of imaging.
  • Not a measurement of anyone. It reports where an arithmetic estimate falls. It does not tell a child what they will be.

What moves a real outcome

Two parents' heights are the only inputs, so everything else that affects adult height is outside the model entirely.

  • Nutrition over years. Sustained undernutrition during growth reduces adult height, and no arithmetic on parental heights sees it.
  • Timing. Two children reaching the same adult height can be far apart at fourteen. Early and late growth spurts make mid-teen height a poor predictor of the finish.
  • Health. Chronic illness and some treatments affect growth. Again, invisible to this calculation.
  • Which parents. The method wants both biological parents' final adult heights. A parent still growing, or an estimate from memory, moves the answer by however much the guess was wrong.

Edge cases and the converter

The other half of this page answers a much simpler question than the prediction does: how tall am I in the other unit. As a height converter it is exact, and converting between feet, inches, feet plus inches, centimetres and metres loses no precision at all.

  • The conversion side is exact. An inch is defined as exactly 2.54 cm, so converting between ft, in, ft plus in, cm and m loses no precision. All the uncertainty on this page belongs to the prediction, not the conversion.
  • Inches must be under 12. In the ft plus in fields, 5 ft 14 in is rejected rather than silently read as 6 ft 2 in.
  • Zero or negative heights. Rejected. There is no reading of a negative parent height that this tool could answer honestly.
  • Adults. The prediction is for a child's eventual adult height. Run on a grown adult it returns arithmetic about their parents, not information about them.

Your figures stay in the page

The heights you enter are processed by this page in your browser. They are not sent to a server, not stored after you close the tab, and not visible to anyone else. There is no account and nothing to sign up for. Family health details deserve that by default rather than on request.

How tall will I be? What this predictor can and cannot tell you

The second mode on this page is a height predictor for a child, and it works from the parents' heights rather than from the child's own. That is the mid-parental method: average the two parents' heights, then add about 2.5 inches for a boy or subtract about 2.5 inches for a girl. It answers "how tall will I be" in the only way arithmetic can, which is roughly.

Be clear about the limits before you rely on it. It uses no growth chart, no bone age, and nothing about the child's current height or stage of puberty, all of which a paediatrician would use. Real adult heights scatter several inches either side of the figure it gives. It is an educational estimate, not a medical prediction, and a child growing well outside the range it suggests is a question for a doctor rather than for a calculator.

The first mode does something much simpler and much more certain: it converts a height you already know between feet, inches, feet plus inches, centimetres and metres. If you just want to know how tall someone is in different units, that mode has no estimate in it at all.

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Frequently asked questions

1 inch is exactly 2.54 cm. So 5 ft 10 in = 70 in × 2.54 = 177.80 cm. The calculator does this for every common unit pair.

For boys, predicted adult height = (mother's height + father's height + 5 in) / 2. For girls, predicted adult height = (mother's height + father's height − 5 in) / 2. The 5-inch adjustment captures the average difference between adult male and female heights.

This calculator shows a band of 4 inches either side of the estimate, which is the spread conventionally quoted with the mid-parental method. Treat it as the tool's own working range rather than a statistical guarantee: this page cites no study for a confidence level, and would rather say so than attach one it cannot point at. Real outcomes depend on nutrition, health, and the timing of growth spurts, and children routinely land outside the band.

The mid-parental estimate is for predicted adult height. It works best when both parents' final adult heights are known. For tracking a growing child's percentile, a pediatrician uses growth charts (CDC or WHO), which this calculator does not include.

By the mid-parental method, which is one average and one adjustment. Add both parents' heights in inches, add 5 for a boy or subtract 5 for a girl, then halve the total. For a mother of 65 inches and a father of 71, a boy comes out at (65 + 71 + 5) ÷ 2 = 70.5 inches, or 179.1 cm. Adding 5 then halving is the same as averaging then adding 2.5, which is how the rule is often written.

Loosely accurate at best, which is why the calculator shows a band of 4 inches either side rather than a single figure. That band spans 8 inches in total. Two children of the same parents can finish at opposite ends of it, and children land outside it regularly. It is a starting point for a conversation, not a forecast.

Because the method was built that way: it adds 5 inches before halving for a boy and subtracts 5 for a girl, which shifts the estimate by 2.5 inches either way. That is a fitted adjustment in the method, not a statement about any individual child, and it is the only place sex enters the arithmetic at all.

No, and it is not close to the right tool for that. Judging whether growth is normal means tracking a child against population percentiles over time, which is what a pediatric growth chart does. This takes two numbers and returns one, and never observes the child. If you have a concern, that is a conversation for a pediatrician.

Bone age is skeletal maturity read from a hand radiograph, and it is how a clinician judges how much growing is left. This calculator does not use it and cannot approximate it. Nothing here looks at the child at all; it works entirely from two parents' heights.

The method needs both, because it averages them. Substituting a guess for the missing parent moves the answer by half of however much the guess was wrong: a parent estimated 4 inches too tall shifts the prediction by 2 inches. If you have to guess, treat the result as correspondingly looser.

Not in any useful sense. It estimates a child's eventual adult height from their parents. Run on someone already grown, it returns arithmetic about their parents rather than information about them, and their actual measured height is the better number by a wide margin.

Yes. An inch is defined as exactly 2.54 centimetres, so converting between feet, inches, feet plus inches, centimetres and metres loses no precision at all. Every bit of the uncertainty on this page belongs to the prediction, not to the conversion.

Because the inches part of a feet-and-inches entry has to be under 12. Silently reading 5 ft 14 in as 6 ft 2 in would be guessing at what you meant, and a rejected entry you can correct is better than an accepted one you cannot see is wrong.

No. Everything you type is processed by the page in your browser. Nothing is sent to a server, nothing is stored after you close the tab, and there is no account.

No. The calculator is an educational tool. For pediatric growth concerns or short stature evaluation, consult a pediatrician who can use growth charts and bone-age imaging.