Toolkeel

BMI calculator

Calculate your body mass index and see where it falls on the standard adult scale, along with the weight range considered healthy for your height.

  • Free
  • Private
  • No sign-up
Units
Units
Your BMI

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Category

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Healthy weight for your height

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Under 18.518.5–24.925–29.930+

For adults aged 18 and over. BMI does not distinguish muscle from fat and is not a diagnosis. Talk to a healthcare professional about your health.

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How to use it

  1. Choose metric or imperial units.

  2. Enter your weight and height.

  3. Read your BMI, its category and your healthy weight range.

About this tool

Body mass index is weight in kilograms divided by height in metres squared. The World Health Organization uses these adult categories: under 18.5 underweight, 18.5–24.9 healthy weight, 25–29.9 overweight and 30 or more obesity.

BMI is a quick screening measure for populations, not an assessment of an individual's health. It does not account for muscle mass, bone density, age, sex or ethnicity, and some health services use different thresholds for people of Asian descent. It is not valid for children, teenagers or pregnant women.

Good to know

  • Adults only.
  • A screening measure, not medical advice or a diagnosis.

Frequently asked questions

What is a healthy BMI?

For adults, the WHO considers 18.5 to 24.9 a healthy range.

How is BMI calculated?

Weight (kg) divided by height (m) squared. For example 72 kg and 1.75 m gives 72 ÷ 3.0625 = 23.5.

Is BMI accurate for athletes?

Not very. Muscular people can have a high BMI without excess fat. Waist measurement and professional assessment give a fuller picture.

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Last updated 2026-10-20 by the Toolkeel team. How we build and check our tools.