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WAVESPEED AI BMI CALCULATOR Works in your browser
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Free BMI CalculatorBody mass index for adults, children and teens.

Enter your height and weight in metric or US units to see your BMI, its category and the healthy weight range for your height.
For ages 2 to 19, get the BMI-for-age percentile from the official CDC growth charts.

Metric & US unitsHealthy weight rangeKids' percentiles
No sign-up Unlimited use Remembers your numbers
BMI is a screening number, not a diagnosis. It does not tell muscle from fat and is not medical advice. Talk to a doctor about your health.
BMI
23.5
Normal weight
Healthy weight for this height
53.5 kg – 72.0 kg
BMI 18.5 to 24.9
In the healthy range
✓
BMI Prime
0.94
BMI ÷ 25; above 1.00 is overweight
Adult BMI categories (World Health Organization)
CategoryBMI
Severe thinness< 16.0
Moderate thinness16.0 – 16.9
Mild thinness17.0 – 18.4
Normal weight18.5 – 24.9
Overweight25.0 – 29.9
Obesity class I30.0 – 34.9
Obesity class II35.0 – 39.9
Obesity class III≥ 40.0
Calculated on your device. What you type is not sent anywhere.
THREE SIMPLE STEPS

How to calculate BMI

01

Choose units

Use kilograms and centimetres, or pounds, feet and inches. Switching converts what you typed.

02

Enter height and weight

For a child or teen, also enter the age and sex: their BMI is compared with others of the same age.

03

Read the result

See the BMI, its category, the healthy weight range for the height and how far you are from it.

Worked examples

Metric

An adult who is 170 cm tall and weighs 68 kg.

  1. Height in metres: 1.70; squared: 2.89.
  2. BMI = 68 ÷ 2.89 = 23.5.
  3. Healthy range at 1.70 m: 18.5 × 2.89 = 53.5 kg to 24.9 × 2.89 = 72.0 kg.

BMI 23.5 – normal weight.

US units

An adult who is 5 ft 10 in (70 in) tall and weighs 180 lb.

  1. BMI = 703 × 180 ÷ 70² = 25.8.
  2. Healthy range at 70 in: about 128.9 lb to 173.5 lb.

BMI 25.8 – overweight; about 6.5 lb above the healthy range.

A 10-year-old girl

140 cm tall, 40 kg, 10 years old.

  1. BMI = 40 ÷ 1.40² = 20.4.
  2. On the CDC chart for 10-year-old girls, the 85th percentile is 20.0 and the 95th is 23.0.

87th percentile – overweight for her age.

The BMI formula

BMI = weight (kg) ÷ height (m)²BMI = 703 × weight (lb) ÷ height (in)²

Adult categories follow the World Health Organization: below 18.5 underweight, 18.5 to 24.9 normal, 25 to 29.9 overweight, 30 and above obesity.

For children and teens, the BMI is compared with the CDC growth charts for the same age and sex: below the 5th percentile is underweight, the 5th to below the 85th is a healthy weight, the 85th to below the 95th overweight, and the 95th and above obesity.

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BMI Calculator FAQ

What is a healthy BMI?

For adults, the World Health Organization calls a BMI of 18.5 to 24.9 normal weight. 25 to 29.9 is overweight and 30 or more is obesity. Below 18.5 is underweight.

How is BMI calculated?

Divide the weight in kilograms by the height in metres squared. In US units, multiply the weight in pounds by 703 and divide by the height in inches squared.

Why is BMI different for children?

Children's bodies change as they grow and differ between boys and girls. Their BMI is compared with children of the same age and sex using the CDC growth charts, and the result is a percentile rather than a fixed range.

Which charts are used for kids?

The official CDC BMI-for-age growth charts for ages 2 to 19 (2000), with the LMS values published by the CDC. Very high results are also shown as a percentage of the 95th percentile, as in the CDC's 2022 extended charts.

Is BMI accurate for athletes?

Not always. BMI does not tell muscle from fat, so muscular people can show as overweight. It also says nothing about where fat is stored. Use it as a starting point and talk to a doctor.

Is this medical advice?

No. This calculator is for information only. A doctor can look at your health as a whole.

Is my data saved?

Your last numbers are kept only in your own browser so they are there next time. Nothing is sent anywhere.

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