BMI Calculator
Calculate your Body Mass Index (BMI) from your height and weight, in imperial or metric units, and see which standard BMI category you fall into.
Units
25.1
Overweight
How it's calculated
BMI is calculated as weight in kilograms divided by height in meters squared: BMI = weight(kg) / height(m)². If you enter imperial units, this calculator converts them to metric first and then applies the same formula.
The result is compared against the standard World Health Organization categories: below 18.5 is underweight, 18.5 to 24.9 is normal weight, 25 to 29.9 is overweight, and 30 or above is obese.
BMI is a simple screening tool based only on height and weight — it doesn't distinguish muscle from fat, so it can be misleading for very muscular or very lean individuals. For a more detailed picture, pair this with the Body Fat Percentage Calculator.
Worked example
A person who is 5'11" (180.34 cm) and weighs 180 lb (81.65 kg) has a BMI of about 25.1, which falls into the "overweight" category — just above the 25.0 threshold.
Frequently Asked Questions
- Is BMI an accurate measure of health?
- BMI is a widely used screening tool, but it has known limitations — it doesn't account for muscle mass, bone density, or where fat is distributed on the body. It's most useful as a general starting point, not a precise diagnostic.
- Why might an athlete have a high BMI?
- BMI only considers height and weight, so very muscular individuals (whose weight comes largely from muscle rather than fat) can show a BMI in the "overweight" or even "obese" range despite having low body fat. The Body Fat Percentage Calculator gives a more direct estimate in these cases.
- What's a healthy BMI range?
- For most adults, a BMI between 18.5 and 24.9 is considered the normal weight range by the WHO and CDC. Healthy ranges can vary by age, sex, and individual circumstances, so consult a healthcare provider for personalized guidance.