Height Percentile Calculator

Using the height percentile calculator

A percentile tells you how a measurement compares with a reference group. If a height sits at the 80th percentile, it is taller than 80 out of 100 people of the same sex and age, and shorter than the other 20.

1. Choose US units (feet and inches) or metric units (centimetres or metres) and enter the height.
2. Select male or female.
3. Enter the age as whole years plus months from the list. For babies and young children the exact age matters, so work it out from the birth date; for adults a rough age is enough.
4. Pick a country from the From list. The country applies to adults only. People under 20 are compared with United States growth data whatever country is selected.
5. Press Calculate Height Percentile.

The result gives three lines: a plain statement such as "top 36th percentile" or "bottom 48th percentile", the percentage of the group you are taller than, and the percentage you are shorter than. The final line tells you which group was used.

How the percentile is calculated

Heights in a group of people of one sex and age are close to a bell-shaped (normal) distribution. If you know the group's mean and standard deviation, you can convert any height to a z-score and then to the share of the group below it.

z = (height − mean) ÷ standard deviation

percent shorter = Φ(z) × 100Φ is the cumulative standard normal distribution.

Example: adult men in the United States average about 175.3 cm with a standard deviation near 6.8 cm. A man who is 177.8 cm (5 ft 10 in) has z = (177.8 − 175.3) ÷ 6.8 = 0.37, and Φ(0.37) is about 0.643. He is taller than roughly 64.3 percent of US men, which the calculator words as the top 36th percentile.

A second example: US women average about 161.3 cm with a standard deviation near 6.2 cm. For a woman of 170 cm, z = 1.40 and Φ(1.40) is about 0.92, so she is taller than about 92 percent of US women.

If the percentage taller than you is below 50, the calculator reports the "bottom" percentile (how far from the bottom you are). Otherwise it reports the "top" percentile. The two ways of saying it are equivalent.

Where the reference data comes from

• Babies up to 23 months are compared month by month using data modelled on the World Health Organization child growth standards.
• From 2 to 19 years the comparison uses United States growth-chart data from the national health and nutrition survey, in half-year steps: an age is moved to the nearest half year, and an age exactly halfway goes to the younger one.
• Adults from 20 use average heights and standard deviations for men and women in each of 134 countries and territories, drawn mostly from national surveys. The world averages are based on a pooled analysis of population surveys by the NCD Risk Factor Collaboration.
• Older adults are given slightly lower averages, because people shrink with age: about 2 percent lower for men in their seventies and 3 percent in their eighties, and a little more for women.

Every country in the From list has its own pair of averages and standard deviations, one for men and one for women, and a separate set is kept for the world as a whole. Some of the figures are estimates, since not every country has measured both sexes or published a standard deviation. The further a height is from the average, the less reliable the percentile becomes, because surveys contain fewer people at the extremes.

Height percentiles for children

For a child, the percentile only means something at a given age, because the average rises quickly. Averages used for United States children are roughly:

Example: a girl aged 8 years 0 months who measures 120 cm has z = (120 − 128.1) ÷ 5.93 = −1.37 and is taller than about 8.6 percent of girls her age, a bottom-10 percentile. Healthy children are found at every percentile; what paediatricians watch most is whether a child keeps following their own curve over time, and a child far below the 3rd or above the 97th percentile is usually looked at more closely.

This tool is for information only and does not diagnose a growth problem. If you are concerned about a child's growth, speak to a paediatrician. See the disclaimer. To project a child's likely adult height, use the height calculator.

Things to keep in mind

• Percentiles describe a population at the time its data was collected. Average height has risen in many countries over the past century.
• A person who grew up in a different country from the one chosen will be compared with a group they may not resemble genetically or nutritionally. For adults, pick the country where you spent your childhood.
• Measurements matter. Height changes by a centimetre or two across the day and depends on posture and shoes.

To see two heights side by side, try the height comparison tool. To relate height to weight, use the BMI calculator.