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Health & Fitness

BMI Calculator

Calculate body mass index (BMI) in metric or imperial units and see the WHO adult category, with the limits of BMI explained.

Your inputs

Results

BMI

22.9 kg/m²

WHO adult category
Healthy weight
BMI (unrounded)
22.8571
BMI Prime (BMI ÷ 25)
0.91

≈Estimate based on the stated model and assumptions

Notes for this result

  • This is a population-level estimate for adults, not a diagnosis. Discuss health decisions with a qualified professional.
  • BMI does not distinguish muscle from fat and is not valid for children, teenagers or pregnancy. Some health bodies use lower cut-offs for people of Asian descent.

Inputs are never added to links for financial, salary or health calculators.

What this calculator does

BMI relates weight to height and is used as a quick population-level screening measure for adults. It is easy to calculate but does not measure body fat directly.

Formula and method

BMI = weight (kg) ÷ height (m)² (imperial inputs are converted exactly: 1 lb = 0.45359237 kg, 1 in = 2.54 cm)

Worked example

Calculated by this tool with its default inputs:

Inputs

  • Units: Metric (kg, cm)
  • Weight: 70 kg
  • Height: 175 cm

Results

  • BMI: 22.9 kg/m²
  • WHO adult category: Healthy weight
  • BMI (unrounded): 22.8571
  • BMI Prime (BMI ÷ 25): 0.91

How to read the results

WHO adult categories: below 18.5 underweight; 18.5–24.9 healthy weight; 25–29.9 overweight; 30 and above obesity (classes I–III).

Assumptions and limitations

  • Not valid for children and teenagers (use age- and sex-specific percentiles), pregnancy, or very muscular people.
  • Some health bodies use lower cut-offs for people of South Asian, Chinese and other Asian heritage.
  • An estimate for healthy adults, not a diagnosis or medical advice. Consult a qualified health professional about your personal situation.

Health results are general estimates for adults and do not replace medical advice, diagnosis or treatment. Speak to a qualified health professional about your personal situation, especially during pregnancy or if you have a medical condition.

Questions

Is BMI accurate?

It is a useful screening tool across populations, but for an individual it can misclassify muscular or older people. Waist measures add useful information.

Sources

  • World Health Organization — Body mass index (BMI) classification for adults

Methodology and verification

Result type
Estimate based on the stated model and assumptions
Formula version
1.0
Automated verification
4 reference and validation test cases, checked against independently computed values. The site cannot be built if any of them fail.
Editorial review
Awaiting human editorial review. The explanation was drafted with AI assistance; the formula and examples are verified by the automated tests above.

Privacy

Everything you enter is calculated in this browser and is not sent to Numerith or anyone else. Because this calculator can involve personal financial or health details, your inputs are never added to share links or saved to history. Privacy policy