Work out your Body Mass Index — then go further, with your healthy weight range, BMR, daily calorie targets for your goal, body fat % and ideal weight.
Measure your waist at the navel, neck just below the Adam's apple, hips at the widest point.
Results update live as you type — the button is just there because pressing it feels good. 😊
🍽 Your nutrition guide — Healthy weight
Your BMI is in the healthy band. The goal now is simple: protect it. These daily targets are calculated from your numbers.
Focus on
A sample day
How to use this tool
Any units you like — kg, lb, stone, cm, feet & inches. Switching units converts your numbers automatically, so your bmi stays identical in every unit.
Add sex, age, goal, activity and waist/neck measurements to unlock BMR, body fat % and calorie targets — including a dedicated bmi calculator women and bmi calculator men view via the sex selector.
Your bmi, category and every extra metric update live as you type — plus how many kg separate you from the healthy range, shown against the bmi scale.
Copy your result, share it, or print it for your records or your doctor.
Formula & worked example
Worked example: a person who weighs 70 kg and is 1.75 m tall: 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 = 22.9 — comfortably inside the healthy band of 18.5–24.9. That is how to calculate bmi with the bmi formula: try it above and the calculator gives the same answer in pounds and inches (154 lb, 5 ft 9 in), because every unit is converted to metric first. To calculate bmi yourself in imperial units: 703 × 154 ÷ 69² = 22.9.
Limitations — read this before you rely on it
BMI is a screening tool, not a diagnosis. It treats muscle and fat as the same thing, so athletes can read as overweight while being perfectly healthy, and older adults can read as healthy while carrying too little muscle. It also does not show where fat is stored — belly fat matters most, which is why this calculator pairs your BMI with waist-to-height ratio and body fat %. BMI is not designed for pregnancy, and children and teenagers (ages 2–19) must be judged on CDC percentiles, not adult bands — this calculator switches to percentiles automatically when an age of 2–19 is entered. If your result worries you, talk to a doctor before making big changes.
Frequently asked questions
For most adults a bmi between 18.5 and 24.9 is considered healthy. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is obese. On the bmi scale, people of South and East Asian heritage face rising health risks earlier, so overweight starts at 23 and obesity at 27.5 — switch on Asian cut-offs in this calculator to use those bands.
To calculate bmi, use the bmi formula: weight in kilograms divided by height in metres squared. In imperial units: BMI = 703 × weight in pounds divided by height in inches squared. This calculator converts everything to metric first, so every unit gives the identical result — try it in kg/cm and again in lb/feet and inches.
The bmi formula itself is the same for everyone, but the extra results differ: BMR and body fat % use sex-specific formulas (Mifflin-St Jeor for BMR, the US Navy method for body fat, which uses hip measurements for women). Choose your sex in Advanced Options and those results adjust automatically.
Not fully. BMI cannot tell muscle from fat, so very muscular people can score as overweight while being healthy. That is why this calculator also shows your waist-to-height ratio and body fat percentage, which give a fuller picture alongside your bmi.
Children and teens are not judged on adult bmi bands. Their bmi is compared with other children of the same age and sex as a percentile: below the 5th percentile is underweight, 5th to 85th is healthy, 85th to 95th is overweight and above the 95th is obese. Enter an age between 2 and 19 in Advanced Options and this calculator switches to CDC percentiles automatically.