BMI Calculator
Calculate your Body Mass Index and see which category you fall in.
Your BMI
24.7
Normal weightYou are within a healthy weight range ✓
🎯 Healthy weight range
59.9 kg – 80.7 kg
for your height (BMI 18.5–24.9)
💧 Body fat
20.3%
Estimated (BMI, age, sex)
⚖️ Fat / lean mass
16.3 kg fat
63.7 kg lean
🧍 Ideal body weight
71.5 kg – 77.3 kg
Devine · Robinson · Miller · Hamwi
📏 Waist-to-height
Add a waist measurement above to see your risk ratio.
📐 BMI Prime · Ponderal
Prime 0.99
PI 13.7 kg/m³
⚠️ BMI doesn't distinguish muscle from fat and isn't suitable for athletes, pregnant women, or children. These figures are educational estimates, not medical advice.
🩺A full body-composition picture, not just a number
BMI (Body Mass Index) compares your weight to your height to place you in a category — but on its own it's a blunt tool. This calculator gives you the BMI and the context that makes it useful: your healthy weight range, an estimate of body-fat percentage, your lean and fat mass, an ideal-weight range from four medical formulas, and your waist-to-height ratio, which many researchers consider a better health predictor than BMI alone.
📊What each number means
- BMI category — the WHO bands from underweight to obese class III, shown on a colour gauge.
- Healthy weight range — the weights that put your BMI between 18.5 and 24.9, plus how much to lose or gain.
- Body fat % — measured accurately with the US-Navy tape method if you add waist and neck (and hip for women), or estimated from BMI, age and sex.
- Ideal body weight — the Devine, Robinson, Miller and Hamwi formulas, shown as a range because no single formula is definitive.
- Waist-to-height ratio — keep it under 0.5; it flags abdominal fat that BMI can miss.
- BMI Prime & Ponderal Index — refinements that behave better for very tall or short people.
🧮The formulas
For imperial units, BMI = 703 × weight (lb) ÷ height (in)². The healthy range comes from solving that for BMI 18.5 and 24.9 at your height. Body fat uses the US-Navy circumference equations when measurements are supplied, otherwise the Deurenberg estimate 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4 (sex = 1 for men, 0 for women).
⚠️Read BMI wisely
- BMI can't tell muscle from fat — a muscular athlete may read 'overweight' while being lean.
- It's not valid for children and teens (who use age/sex percentiles) or during pregnancy.
- Waist-to-height ratio and body-fat % give a fuller picture — use them alongside BMI.
- Any single reading is a snapshot; trends over time matter more than one number.
💡 Frequently Asked Questions
How is BMI calculated?+
BMI = weight (kg) ÷ height (m)². In imperial units it's 703 × weight (lb) ÷ height (in)². A BMI of 18.5–24.9 is considered a healthy range for most adults.
Is BMI accurate for everyone?+
No. BMI doesn't distinguish muscle from fat, so it can misclassify athletes, and it isn't appropriate for children, pregnant women, or the very elderly. Use the body-fat % and waist-to-height ratio here for more context.
How do you measure body fat here?+
If you add your waist and neck (and hip for women), it uses the US-Navy tape method, which is fairly accurate. Without those, it estimates body fat from your BMI, age, and sex using the Deurenberg formula.
What is the waist-to-height ratio?+
It's your waist measurement divided by your height. Keeping it under 0.5 is a simple, widely-used marker of healthy body-fat distribution — and it catches abdominal fat that BMI can overlook.