Child height predictor: how tall will my child be?

Free calculator · No sign-up · Works on any phone · Updated 9 Oct 2026

"How tall will my child be?" is one of the most common questions parents ask, usually while looking at a toddler who seems to have grown overnight. While no one can predict height exactly, doctors use simple, well-tested methods to estimate a child's likely adult height from the parents' heights. This free child height predictor uses the mid-parental height method that paediatricians use, shows the likely range, and lets you cross-check with the "double the height at two" rule.

1. How to use the height predictor

1. Choose boy or girl. The formula is slightly different, because adult men are on average about 13 cm (5 inches) taller than adult women.
2. Choose your units. Enter heights in centimetres, or switch to feet and inches.
3. Enter both biological parents' heights. Use measured heights if you can, standing straight without shoes. Guessed heights are often off by a few centimetres, which changes the result.
4. Add your child's height at age 2 (optional). For boys, use the height at their second birthday; for girls, at 18 months. This gives a second, independent estimate.
5. Tap "Predict adult height" to see the estimate in both centimetres and feet and inches, with the likely range.

All calculations happen on your device. Nothing is stored or shared.

2. The mid-parental height formula

The method used by this calculator is called mid-parental height (or target height). It was described by the British paediatrician James Tanner and is still used by doctors around the world, because children's adult height is strongly linked to their parents' heights.

The 13 cm (5 inches) adjusts for the average difference between adult men and women. In effect, the formula averages the two parents' heights after "converting" the opposite-sex parent's height to the child's sex.

Worked example

A father who is 172 cm and a mother who is 158 cm:

• For a son: (172 + 158 + 13) ÷ 2 = 171.5 cm (about 5 ft 8 in). Likely range: 163 to 180 cm.
• For a daughter: (172 + 158 − 13) ÷ 2 = 158.5 cm (about 5 ft 2 in). Likely range: 150 to 167 cm.

The range of about 8.5 cm either side of the estimate is the commonly used "target range". Most children's adult height falls inside it, but some end up taller or shorter.

3. The "double the height at two" rule

An old rule of thumb, often mentioned by doctors and grandparents alike: a boy's height at his second birthday, doubled, roughly equals his adult height. For girls, who mature earlier, use the height at 18 months.

For example, a boy who measured 87 cm on his second birthday might reach around 174 cm as an adult. The rule is less precise than the mid-parental method, and it depends on an accurate measurement at exactly the right age, but it is a useful cross-check. When both methods give similar answers, you can be a little more confident in the estimate.

4. How accurate is height prediction?

Height prediction gives you a reasonable estimate, not a guarantee. Things to keep in mind:

• Genetics is the biggest factor, but not the only one. Studies of twins and families suggest that most of the variation in adult height between people is linked to genes. The rest comes from nutrition, health and environment.
• Parents' heights are only part of the genetic picture. Grandparents and other relatives carry genes too, which is why siblings with the same parents can differ noticeably in height.
• Each generation tends to be a little taller where nutrition and healthcare have improved. Your child may end up slightly taller than the formula suggests.
• Timing of puberty matters. Early and late developers can look very different at 12 and end up the same height at 20.

Doctors use more detailed methods when there is a medical concern, such as a bone-age X-ray combined with current height. For everyday curiosity, the mid-parental method is the standard and most practical approach.

5. How children grow, year by year

Children do not grow at a steady rate. Growth is fastest in the first year, slows through the preschool and primary years, and speeds up again in puberty. Typical growth rates are roughly:

Girls usually start their growth spurt earlier (often between about 10 and 12 years) and stop growing earlier, while boys typically start later and grow for longer. Most girls reach close to their adult height by their mid-teens, and most boys a few years later.

Growth also happens in bursts. Many parents notice a child "shooting up" over a few weeks, often with a bigger appetite and longer sleep, followed by a slower period. Measuring every few months, rather than every week, gives a clearer picture.

6. What affects a child's height

• Genes: inherited from both parents and the wider family. This is why the formula starts with parents' heights.
• Nutrition: enough energy, protein, calcium, iron, zinc and vitamins, especially in the first few years. Long-term undernutrition can limit growth.
• Sleep: growth hormone is released in pulses, with a large share released during deep sleep at night.
• Physical activity: active play supports healthy bones, muscles and appetite.
• Overall health: repeated infections, untreated long-term conditions, and some medicines can slow growth.
• Hormones: thyroid and growth hormones both play a role. Problems are uncommon but treatable when found.

Note what is not on the list: stretching exercises, special "height increase" powders or hanging from bars. There is no good evidence that these change adult height in healthy children. Be wary of products that promise to make children taller.

7. Healthy habits that support growth

You cannot change your child's genes, but you can make sure nothing holds back their natural growth. The basics are simple:

• Balanced meals: dal, eggs, milk and curd, paneer, fish or meat if your family eats them, green vegetables, fruit and whole grains. Variety matters more than any single "superfood".
• Enough sleep: 10 to 13 hours (including naps) for 3 to 5 year olds, and 9 to 12 hours for 6 to 12 year olds. Our kids bedtime calculator works out the right bedtime from your child's wake-up time.
• Daily active play: running, climbing, cycling and outdoor games. Children aged 3 to 5 benefit from being active throughout the day.
• Less screen time: long hours on screens usually mean less active play and later bedtimes. Our screen time calculator shows how it adds up.
• Regular check-ups: height and weight measured at routine visits and plotted on a growth chart.

8. When to talk to a doctor

Most children who are shorter or taller than their friends are perfectly healthy and simply following their family pattern. It is worth checking with your paediatrician if:

• Your child is growing much more slowly than the typical rates above, for example less than about 4 cm a year after age 3.
• On a growth chart, your child's height has dropped across two or more of the major percentile lines.
• Your child is much shorter or much taller than the range predicted from your family heights.
• There are other signs, such as poor appetite, frequent illness, unusual tiredness, or very early or very late signs of puberty.

Your doctor can measure accurately, plot growth over time, and decide whether any tests are needed. Growth problems that need treatment are uncommon, but they are much easier to help when found early.

Measuring your child at home

1. Remove shoes, hair clips and thick socks.
2. Stand your child with heels, bottom, shoulders and the back of the head against a flat wall, feet together.
3. Ask them to look straight ahead.
4. Place a flat book on top of the head, at a right angle to the wall, and mark where it touches.
5. Measure from the floor to the mark with a tape measure. Note the date.

Measuring at the same time of day each time helps, as children are slightly taller in the morning than in the evening.

9. Understanding growth charts and percentiles

A height prediction tells you where your child might end up. A growth chart tells you how they are growing right now. Doctors plot height and weight at each visit and look at the pattern over time, which is far more useful than any single measurement.

Growth charts are drawn as curved lines called percentiles. If your child's height is on the 25th percentile, it means that out of 100 children of the same age and sex, about 25 would be shorter and 75 taller. Important points:

• Any percentile can be healthy. A child on the 10th percentile with short parents may be growing perfectly.
• The trend matters most. Healthy children usually follow roughly the same percentile line over the years. Crossing two major lines downwards is worth discussing with a doctor.
• Use the right chart. For children under five, doctors widely use the WHO Child Growth Standards. For older children in India, the Indian Academy of Pediatrics publishes growth charts based on Indian children.
• Ask for the chart. Many paediatricians will show you your child's growth chart if you ask. Your child's health card may also have one.

The mid-parental height estimate can be plotted on the adult end of a growth chart. If your child's current percentile lines up with the predicted adult height, they are growing in line with their family pattern.

10. A sample day of growth-friendly food for a 4 year old

There is no special diet for height, but a varied, balanced diet gives children the protein, calcium, iron and energy they need. A simple day might look like this (adjust for your family's food habits):

Keep sugary drinks, packaged snacks and fried foods occasional. Offer water through the day. If your child is a very fussy eater, or you are worried about their weight or energy, ask your paediatrician; a simple blood test can check for common problems like iron deficiency.

11. Height myths parents hear

• "Hanging from a bar makes children taller." It is good exercise, but there is no evidence it changes adult height.
• "Height powders and drinks guarantee growth." Children who already eat a balanced diet do not grow taller from supplements. Be cautious of strong marketing claims.
• "Lifting weights stunts growth." Supervised, age-appropriate strength activities are generally considered safe for older children. For young children, active play is all they need.
• "A small baby will be a short adult." Birth size is influenced by many things during pregnancy. Many small babies catch up within the first two years.
• "Coffee or tea stunts growth." There is no good evidence for this, although caffeine is not recommended for young children for other reasons, such as sleep.

12. Keeping a simple growth record at home

A home record makes conversations with your doctor much easier, and children love seeing how much they have grown. Keep it simple:

• Measure every six months, for example on the birthday and the half-birthday. Our kids age calculator shows both dates.
• Write down the date, height and weight in a notebook or a note on your phone.
• Work out the yearly growth by subtracting last year's height from this year's. Compare it with the typical rates above.
• Mark it on a wall chart or a door frame. Children are proud to see the marks climb.

If the yearly growth is much lower than expected for two measurements in a row, show your record to your paediatrician at the next visit.

13. Questions parents ask

How can I predict my child's adult height?

Use the mid-parental formula: for a boy, add the father's and mother's heights in cm, add 13 and divide by 2. For a girl, subtract 13 instead of adding it. Most children end up within about 8.5 cm of this figure.

How accurate is the mid-parental height formula?

It gives a reasonable estimate, not a guarantee. Genes from the wider family, nutrition, health, sleep and the timing of puberty all affect final height, so some children end up outside the predicted range.

Is it true that height at age 2 doubled equals adult height?

It is a rough rule of thumb: double a boy's height at age 2, or a girl's height at 18 months. It is less precise than the mid-parental method but is a useful cross-check.

How much do children grow each year?

Roughly 25 cm in the first year, 10 to 12 cm in the second, 8 to 9 cm in the third, then about 5 to 7 cm a year until the growth spurt of puberty.

Can exercises or supplements make my child taller?

There is no good evidence that stretching, hanging or special height-increase products change adult height in healthy children. Good food, enough sleep, active play and regular check-ups help a child reach their natural potential.

When should I worry about my child's height?

Talk to your paediatrician if your child grows much more slowly than usual, drops across percentile lines on a growth chart, is far outside the range predicted from family heights, or has other symptoms such as poor appetite or frequent illness.