Handy tools
BMI Calculator
Check your BMI with WHO or Asian cutoffs, see the healthy weight range for your height, and compare 4 ideal weight formulas.
Body Mass Index compares your weight with your height squared (kg/m²). Pick the cut-offs that fit you — the Asia-Pacific scale flags health risk at a lower BMI than the global WHO scale — and switch freely between cm/kg and ft/in/lb.
WHO international: overweight from 25, obesity from 30.
Normal weight
- Category
- Normal weight
- Healthy weight for your height
- 53.4 kg – 72.1 kg
- To the healthy range
- Already in range
- BMI Prime BMI ÷ 25. 1.00 marks the WHO overweight line.
- 0.90
WHO ranges
- Underweight< 18.5
- Normal weight18.5–24.9
- Overweight (pre-obese)25–29.9
- Obesity class I30–34.9
- Obesity class II35–39.9
- Obesity class III≥ 40
BMI doesn't account for muscle mass, age, sex or pregnancy, so it is a screening number, not a medical diagnosis. Children and teens (WHO: ages 5–19) are assessed with age- and sex-specific BMI percentiles instead.
Ideal weight: 4 formulas compared
Four long-standing ideal-body-weight formulas, side by side with the BMI healthy range for your height.
| Formula | Ideal weight | You vs. ideal |
|---|---|---|
| Devine (1974) | 65.9 kg (145 lb) | −0.9 kg |
| Robinson (1983) | 65.2 kg (144 lb) | −0.2 kg |
| Hamwi (1964) | 66.7 kg (147 lb) | −1.7 kg |
| Miller (1983) | 66.0 kg (146 lb) | −1.0 kg |
| BMI healthy range (WHO) | 53.4 kg – 72.1 kg | |
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Find your BMI in cm/kg or in feet, inches and pounds, shown on a color-coded band. Switch between WHO cutoffs (25/30) and Asian cutoffs (23/25, used in Korea); the China (24/28), Taiwan (24/27) and Japan JASSO standards appear on those language versions. Wondering about the healthy weight range for your height? It appears for your exact height, with how far you are from it and your BMI Prime. The ideal weight calculator compares the Devine, Robinson, Hamwi and Miller formulas side by side. Share a link that restores your inputs, units and sex, or jump to the body fat and BMR calculators. Free, no sign-up. BMI is a screening number, not a diagnosis: it can't tell muscle from fat, ignores age and pregnancy, and children and teens are assessed with BMI-for-age percentiles instead.
Frequently Asked Questions
Q. What is a normal BMI for adults?
A. Under the WHO classification, a BMI of 18.5 to 24.9 is normal weight, 25 to 29.9 is overweight and 30 or above is obesity; below 18.5 is underweight. Asia-Pacific guidelines move the overweight and obesity lines down to 23 and 25.
Q. Why are Asian BMI cutoffs lower than WHO?
A. Asia-Pacific guidelines set overweight at 23 and obesity at 25 because weight-related health risks tend to appear at a lower BMI in many Asian populations. Switch standards to see how your category changes.
Q. How do you calculate BMI?
A. Divide your weight in kilograms by your height in meters squared. In US units, multiply your weight in pounds by 703 and divide by your height in inches squared: 154 lb at 5 ft 9 in (69 in) gives about 22.7. BMI Prime is simply your BMI divided by 25.
Q. What are the limits of BMI?
A. BMI can't tell muscle from fat, so muscular people may read as overweight, and it says nothing about where fat is stored. Waist size adds that: WHO links higher risk to a waist above 94 cm (37 in) in men and 80 cm (31.5 in) in women. Adult categories don't apply to children, teens or pregnancy.
Q. Which ideal weight formula is most accurate?
A. None is definitive. Devine, Robinson, Hamwi and Miller were built from different data and give a spread of results, so treat them as a rough range rather than a target. For personal advice, talk to a healthcare professional.