BMI calculator

Body mass index (BMI) compares your weight to your height. It's a quick screening number, not a diagnosis.

ft
in
lb
Your BMI
25.8
Overweight
Healthy weight for your height
129 lb – 174 lb
Distance from healthy range
6.5 lb above the range
BMI Prime
1.03
BMI ÷ 25. Under 1.0 is below the overweight line.
Adult BMI categories (WHO)
BMICategory
Below 18.5Underweight
18.5 – 24.9Healthy weight
25 – 29.9Overweight
30 – 34.9Obesity class I
35 – 39.9Obesity class II
40 and aboveObesity class III
  • BMI doesn't distinguish muscle from fat. Very muscular people can show as 'overweight' while being lean; check your body fat for a fuller picture.

How BMI is calculated

BMI = weight (kg) ÷ height (m)². In US units: 703 × weight (lb) ÷ height (in)². The same formula and categories apply to adult men and women.

What BMI tells you, and what it doesn't

At a population level, a higher BMI is linked with higher risk of heart disease, type 2 diabetes and other conditions, which is why doctors use it as a quick screen. But it can't tell muscle from fat, says nothing about where fat is stored, and works less well for athletes, older adults and some ethnic groups. Some Asian health bodies use lower cutoffs (23 for overweight, 27.5 for obesity).

Better measures to pair with BMI

  • Body fat percentage separates fat from muscle.
  • Waist circumference: above 40 in (102 cm) for men or 35 in (88 cm) for women signals higher risk.
  • Waist-to-height ratio: keeping your waist under half your height is a simple target.

Frequently asked questions

What is a healthy BMI?
For adults, 18.5 to 24.9 is classified as a healthy weight by the World Health Organization.
Is BMI different for men and women?
The formula and adult categories are the same. Women typically carry more body fat than men at the same BMI, which is one reason BMI is only a rough guide.
Is BMI accurate for muscular people?
Not very. Muscle is dense, so muscular people often have a high BMI with low body fat. A body fat estimate is more useful for them.

These results are estimates for healthy adults and are not medical advice. If you are pregnant, breastfeeding, under 18, or managing a medical condition, talk to your doctor or a registered dietitian.

Related calculators

Body fat calculator
Estimate body fat percentage with a tape measure using the U.S. Navy method.
FFMI calculator
Fat-free mass index: how muscular you are for your height.
Calorie deficit calculator
Daily calories to lose weight at a safe pace, and how long it takes.