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BMI Calculator🔒 100% local
Calculate your Body Mass Index. Supports metric and imperial units.
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Works out body mass index from a weight and a height, in kg/cm or lbs/in, and prints the BMI to one decimal, the category band it falls into, and the weight range that would put the same height inside 18.5-24.9. Both fields must be positive numbers; anything else shows a validation message instead of a result. No history is kept between visits.
How to use it
- Switch the unit toggle; the field labels change from kg/cm to lbs/in.
- Enter the weight and the height in that unit, then press Calculate BMI.
- Copy the four-line result if you want to keep the numbers.
Worked example
70 kg, 175 cm (metric)becomesBMI: 22.9
Category: Normal weight
Healthy BMI range: 18.5 - 24.9
Healthy weight for your height: 56.7 - 76.3 kgFrom the tool's own formula, 70 / (1.75 x 1.75); recalculated in Node to confirm the rounding.
200 lbs, 70 in (imperial)becomesBMI: 28.7
Category: Overweight
Healthy BMI range: 18.5 - 24.9
Healthy weight for your height: 58.5 - 78.7 lbsImperial path multiplies by 703: 703 x 200 / (70 x 70).
When to use it
- Producing the BMI number a form or a screening questionnaire asks for.
- Finding the weight window for a given height before setting a diet or training target.
- Checking the same person's figure in both unit systems after a scale switches to pounds.
What it does not do
- The bands are the WHO adult cut-offs applied to every input; they are not the ones used for children, and BMI is not read the same way in pregnancy.
- BMI cannot separate muscle from fat, so a trained athlete often lands in Overweight with a low body-fat percentage.
- Imperial height is inches only: 5 ft 9 in must be typed as 69, and 5.9 quietly gives a wrong answer.
- Metric height is centimetres, and the tool does not stop you typing 1.75, which returns a BMI in the tens of thousands instead of a unit warning.