BMI Calculator
Calculate your Body Mass Index from your height and weight, and see your WHO weight category and healthy range.
What BMI Is and the WHO Categories
Body Mass Index is a quick way to check if your weight sits in a healthy range for your height. It gives one number from two measurements, so you can compare yourself against population bands set by the World Health Organization.
The adult bands are simple. A BMI under 18.5 is underweight. From 18.5 to 24.9 is normal weight. From 25 to 29.9 is overweight. A BMI of 30 or above is obese. A person at 70 kg and 175 cm scores 22.9, which sits comfortably in the normal band. The same height at 90 kg scores 29.4, near the top of the overweight band.
How BMI Is Calculated
The formula is weight in kilograms divided by height in metres squared, so the unit is kg/m². Take 90 kg and 175 cm. The height of 1.75 m squared is 3.0625. Then 90 divided by 3.0625 gives 29.4. That is all there is to it.
If you prefer pounds and inches, the calculator converts them to kilograms and centimetres before it runs the math, so the result is the same either way. The result panel also shows the healthy weight range for your height, which is the span of weights that keep your BMI between 18.5 and 24.9.
The Limits of BMI
BMI does not measure body composition. It cannot tell muscle from fat. A trained athlete with dense muscle may read as overweight while carrying very little fat. For a more direct estimate of fat, use the body fat calculator, which uses tape measurements rather than weight alone.
BMI also ignores where fat sits, and fat around the belly carries more risk than fat on the hips. Age and sex change the picture too. Two people with the same BMI can have very different amounts of fat. Treat the number as a starting check, not a verdict on your health.
What to Do Next
If your BMI sits outside the normal band, the next step is a plan. To find a target weight for your height, try the ideal weight calculator. To work out the calories that match your goal, use the calorie calculator or the TDEE calculator.
To lose weight, you need to eat below the energy you burn. The calorie deficit calculator shows how big a daily gap produces a steady weekly loss. Progress is easier to hold when you can see it.
Tracking your weight over weeks beats checking it once. The Velpa app logs your weight and steps in one private place, so you can watch the trend and see if your changes are working.
Frequently asked questions
- What is BMI and what counts as a healthy number?
- BMI stands for Body Mass Index. It compares your weight to your height with the formula weight in kg divided by height in metres squared. The WHO bands for adults are: under 18.5 underweight, 18.5 to 24.9 normal weight, 25 to 29.9 overweight, and 30 or above obese. A person at 70 kg and 175 cm has a BMI of 22.9, which sits in the normal range.
- How is BMI calculated?
- BMI is your weight in kilograms divided by the square of your height in metres, so the unit is kg/m². For 90 kg and 175 cm, the height is 1.75 m. Squared that is 3.0625, and 90 divided by 3.0625 gives 29.4, which lands in the overweight band. If you enter pounds or inches, the calculator converts them to kg and cm first.
- Why can BMI be wrong for some people?
- BMI uses only weight and height. It does not separate muscle from fat. A lifter with heavy muscle can read as overweight while carrying little fat. An older adult with low muscle can read as normal while carrying too much fat. BMI also ignores where fat sits, and belly fat carries more health risk than fat on the hips.
- What is a healthy weight for my height?
- The healthy range is the weight that gives a BMI of 18.5 to 24.9 at your height. The calculator shows it in kilograms in the result panel. At 175 cm that range runs from about 56.7 kg to 76.3 kg. Your own figures appear once you enter your height and weight.
- Does BMI work the same for everyone?
- No. The standard adult bands suit most people aged 18 to 65, but they do not fit children, pregnant women, or athletes well. Some research bodies use lower cut-offs for South Asian populations because health risk rises at a lower BMI. Treat BMI as one screening signal, then look at waist size, body fat, and blood markers for a fuller picture.