Height calculator: how tall will I be?

Built by Nitin Raja · Last updated October 24, 2026

What a height calculator can tell you

"How tall will I be?" is one of the most common questions teenagers ask, and "how tall will my son be?" one of the most common questions parents ask. A height calculator gives a sensible estimate of adult height from things you already know. It's a height predictor, not a crystal ball: it tells you the most likely adult height and a realistic range around it. Genetics explains most of the difference in height between people - roughly 60-80% - so the parents' heights are the best single clue. Nutrition, sleep, health and the timing of puberty account for the rest.

This height estimator is a child height calculator for any age, from toddler to teen. It uses the two methods that paediatricians use for a first estimate. Both work for boys and girls, and both let you measure heights with your phone camera or type them.

Child height predictor based on parents: the mid-parental method

The parents'-heights method, usually called the mid-parental (or midparental) height, was popularised by the growth researcher J. M. Tanner. It starts from the average of the mother's and father's heights and adjusts for the roughly 13 cm (5 inch) difference between adult men and women:

• Boys: (mother's height + father's height + 13 cm) ÷ 2
• Girls: (mother's height + father's height − 13 cm) ÷ 2

In inches, add or subtract 5 instead of 13. About 95% of children end up within 8.5 cm (3.3 inches) of that figure, which is the "likely range" the calculator shows. It's the simplest height calculator based on parents, and it's surprisingly good for how little it needs. (It's also written midparental height calculator.) For this method on its own - with charts for common parent heights - use the dedicated mid-parental height calculator.

Height calculator: boys

How tall will my son be? A worked example.

Say the mother is 163 cm (5′4″) and the father is 178 cm (5′10″). For a boy: (163 + 178 + 13) ÷ 2 = 177 cm, about 5′9½″. His likely adult range is 168.5 to 185.5 cm - roughly 5′6½″ to 6′1″. As a height predictor for boys, that's the number to expect if his growth follows the family pattern.

Height calculator: girls

How tall will my daughter be?

With the same parents, a girl's prediction is (163 + 178 − 13) ÷ 2 = 164 cm, about 5′4½″, with a likely range of 155.5 to 172.5 cm. The height predictor for girls simply swaps the +13 for −13, because on average women end up about 13 cm shorter than men from the same family.

Baby height predictor: the age-2 method

If you don't know both parents' heights - or you're curious how a toddler is tracking - the second method uses the child's own height. It's an old rule of thumb that still holds up reasonably well: boys reach about half their adult height at age 2, and girls at about 18 months. Double the height at that age and you have a rough future height. Measure a two-year-old lying down or standing against a wall; toddlers rarely stand still for long, so take the best of a few tries.

This baby height calculator is rougher than the parents' method, so the range it shows is wider (about ±10 cm). If you have both, trust the parents' method more.

Why we built this height calculator

Before building CheckMyHeight, I tested a lot of height and sizing websites to see what people need and what gets in the way. "How tall will I be" is full of quizzes that ask about shoe size, sleep or favourite sport, which are not validated predictions, and of calculators that give one confident number without saying which method produced it. The methods paediatricians actually use for a first estimate are simple and public, but they come with a range, and that range is the honest part of the answer.

So this calculator uses only those published methods, always shows the range, and lets you measure the parents or the child with your phone camera, because a prediction built on remembered or rounded heights inherits their error.

What this height calculator measures

You choose a method and whether the child is a boy or a girl, then enter heights in centimetres, metres or feet and inches, or tap the camera button to measure. The calculator then does exactly this:

• From parents' heights (the mid-parental method popularised by J. M. Tanner): (mother + father + 13 cm) ÷ 2 for a boy, minus 13 cm for a girl, with a likely range of ±8.5 cm.
• From height at age 2 (girls: at 18 months): the child's height doubled, with a wider range of ±10 cm because this rule of thumb is rougher. It accepts toddler heights from 45 to 120 cm.
• A comparison: a well-known person of the same sex from our celebrity catalogue whose listed height is close to the prediction, so the number is easier to picture.

The formulas were last checked on 24 October 2026. What it does not measure: bone age, puberty timing, nutrition or health, which are what doctors add for a closer prediction, and it does not use the Khamis-Roche method, which needs the child's current weight and age. It is an estimate for curiosity and planning, not medical advice.

Why this height calculator is different

• Only published methods, named on the page, with the formula written out and worked examples for a boy and a girl.
• A range every time, sized to the method: ±8.5 cm or ±10 cm.
• Measure instead of guessing: each height box has a camera button that measures a parent or child with the phone.
• Any units, centimetres or feet and inches, with the answer in both.
• No account, no quiz and nothing sent. The calculation runs in your browser and the heights are not stored.
• The height boxes start empty, and the prediction appears only after you enter real numbers.

Height calculator comparison: which method is more accurate?

Both methods in this future height calculator give a projected, or expected, adult height - think of the result as a projected height calculator estimate with a range, not a fixed number. You can type heights in feet or use it as a height calculator in cm; it converts automatically.

How tall will I be? A guide for teenagers

If you're a teenager, use your own parents' heights: the adult height calculator gives the same answer for you as it would for your parents asking about you. A few things are worth knowing:

• Growth spurts come at different ages. Girls usually grow fastest around 10-14, boys around 12-16. Starting later doesn't mean ending up shorter.
• Most girls reach adult height around 14-16, about two years after their first period. Most boys stop between 16 and 18, with some growing a little into their early twenties.
• If you've already had your growth spurt, your current height is probably close to your final height - the projected height from the calculator is most useful earlier.

What affects your final height?

The genes you inherit set the range; the environment decides where in that range you land. Good nutrition - enough protein, calcium, vitamin D and overall calories - matters most in childhood. Regular sleep matters because growth hormone is released mainly during deep sleep. Long-term illness, some medicines and hormone conditions can slow growth. On the other hand, no stretching routine, supplement or exercise will make an adult taller once growth has finished.

Whole populations have grown taller over the last century as diets and health improved. South Korean women, for example, are about 20 cm taller on average than a century ago - which is why a child today can end up taller than a mid-parental prediction based on older generations.

How to check growth plates are open (or closed)

Growth plates are areas of cartilage near the ends of the long bones where new bone forms. Once they close (fuse), height growth stops. The only reliable way to know whether they are open is an X-ray - usually of the left hand and wrist - read by a doctor as a "bone age". Still growing taller every few months is a good sign they're open, but it isn't proof, and there's no dependable way to check at home.

When to talk to a doctor

A height calculator is for curiosity and planning, not diagnosis. Talk to your paediatrician if a child's growth seems to have stalled, if they're much shorter or taller than their prediction, or if puberty starts very early or very late. Doctors compare measurements with growth charts over time, which says far more than any single estimate.

Measure first, then predict

The prediction is only as good as the heights you put in. Use the 📏 button next to each box to measure a parent or child with your phone camera - it takes about 30 seconds per person and needs no tape measure. Then compare the result with the average height for men and women, or put the whole family side by side on the height comparison chart.