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BMI calculator

Enter your height and weight for an estimate of your adult BMI and the healthy weight range for your height.

Estimated BMI

24.2Healthy weight range
Healthy range at 170 cm53.5 kg to 72 kg

An estimate for adults aged 18 and over, not medical advice. BMI cannot tell muscle from fat, and it reads differently for some ethnic backgrounds. If you are worried about your weight, talk to a GP or pharmacist.

See your height on the comparison board
BMI is weight in kilograms divided by height in metres squared. For adults, 18.5 to 24.9 is the healthy range, 25 to 29.9 is overweight and 30 or more is obese. It is a quick screening estimate rather than a diagnosis, and it works for adults aged 18 and over only.

Worked example

  1. Inputs 1.75 m · 70 kg
  2. Working 70 ÷ 1.75²
  3. Result BMI 22.9 · healthy
Someone who is 1.75 m (5'9") and weighs 70 kg (11 st) has a BMI of 22.9, inside the 18.5 to 24.9 healthy range. At that height the range runs from about 56.7 kg to 76.3 kg.

Method and sources

We use BMI = kg ÷ m², rounded to one decimal place, with the adult categories published by the World Health Organization (18.5, 25 and 30). The healthy weight range shown is the weight that gives a BMI of 18.5 to 24.9 at the height you enter.

The NHS notes that adults of Asian, Black African, African-Caribbean and Middle Eastern backgrounds can face a higher risk of health problems at a lower BMI, so lower thresholds are sometimes used. Nothing you type is sent anywhere; the sum runs in your browser.

Frequently asked questions

How is BMI calculated?

BMI is your weight in kilograms divided by your height in metres, squared. For example, 70 kg at 1.75 m is 70 ÷ (1.75 × 1.75) = 22.9. If you use pounds and inches the formula is the same once converted, which is what this calculator does for you.

What is a healthy BMI for an adult?

The World Health Organization and the NHS both use 18.5 to 24.9 as the healthy weight range for adults, with under 18.5 labelled underweight, 25 to 29.9 overweight and 30 or more obese. The range is a screening guide, not a verdict on any one person.

Does height change what a healthy weight is?

Yes. Because BMI squares your height, the healthy weight range rises quickly as you get taller: at 160 cm it is roughly 47 to 64 kg, while at 190 cm it is roughly 67 to 90 kg. This calculator shows the range for your own height.

Is BMI accurate for athletes or very muscular people?

Not always. BMI cannot tell muscle from fat, so a muscular person can land in the overweight range without carrying excess body fat. It also says nothing about where fat is stored. Waist measurement and a conversation with a health professional give a fuller picture.

Do the BMI ranges differ by ethnic background?

The NHS notes that adults of Asian, Black African, African-Caribbean and Middle Eastern backgrounds can face a higher risk of health problems at a lower BMI, so lower thresholds are sometimes used for them. If that applies to you, a GP can advise on what is right for you.

Can I use this BMI calculator for children?

No. For under-18s BMI has to be compared with age- and sex-specific growth charts. Our growth percentile calculator is the better starting point, and a GP or school nurse can interpret the result.

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