Health & dates
BMI Calculator (Body Mass Index)
How to use this tool
- 1
Choose the unit system (metric or imperial).
- 2
Enter your height, weight and age.
- 3
Read your BMI, its category and your position on the scale.
- 4
Check the weight range matching a BMI of 18.5 to 24.9 for your height.
Help
- Enter height and weight in kilograms and centimetres, or in pounds, feet and inches: BMI, category and the “healthy” weight range for your height update live.
- Categories follow the WHO adult scale: underweight (< 18.5), normal weight (18.5 to 24.9), overweight (25 to 29.9) and obesity class I, II and III (≥ 30, 35, 40). The category is read from the displayed value rounded to 1 decimal.
- BMI for children and teenagers (under 18) is not covered: it is read on growth charts by age and sex. If you enter an age under 18 the tool says so and gives no category.
- It is a statistical marker, indicative and not medical advice: it cannot tell muscle from fat and suits athletes, pregnant women and older people less well.
Frequently asked questions
How is BMI calculated?
Divide weight in kilograms by the square of height in metres. Example: 70 kg at 1.75 m gives 70 ÷ 3.0625 = 22.9, i.e. normal weight. In imperial units, pounds and inches are converted exactly before the calculation.
Is BMI reliable for a child or teenager?
Not with adult cut-offs. For children, BMI is compared with growth charts that depend on age and sex. This tool therefore gives no interpretation under 18: ask a health professional.
What does the “healthy” weight range mean?
It is the weight that, for your height, gives a BMI between 18.5 and 24.9. It is indicative: other factors (age, muscle mass, history) matter. It is not a medical weight target.
Written and verified by the MaxyTools team · Updated on
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