A weight on its own doesn't mean much — BMI adjusts for height, so a taller and a shorter person carrying the same weight get a fair, like-for-like comparison.
BMI is a quick screening measure used by doctors worldwide, but it doesn't directly measure body fat or muscle — it's a starting point, not a final answer.
Each category covers a wide range of healthy body types. Two people with the same BMI can look and feel very different from one another.
Athletes, older adults, and pregnant women often fall outside standard BMI assumptions — check with a doctor for guidance tailored to you.
Body Mass Index (BMI) is a simple screening tool that uses your height and weight to estimate whether you fall into an underweight, healthy, overweight, or obese range. It's been used by doctors and public health researchers for decades because it's quick to calculate and doesn't require any special equipment — just a scale and a measuring tape.
BMI is calculated by dividing your weight in kilograms by your height in meters, squared:
BMI = weight (kg) ÷ height (m)²
For example, someone who weighs 70kg and is 1.75m tall would have a BMI of 70 ÷ (1.75 × 1.75) = 22.9, which falls in the "Normal weight" range.
If any of these apply to you, our Body Fat % Calculator can give a more complete picture alongside your BMI number. And if your goal is weight management day to day, the Calorie & TDEE Calculator is a natural next step.
A BMI between 18.5 and 24.9 is generally considered a healthy range for most adults.
No — the BMI formula and categories are the same for adult men and women. Body composition naturally differs between sexes, which is one reason BMI is only a starting point.
No. Children and teens use age- and sex-specific BMI percentile charts, not the standard adult categories used here.
Yes. BMI doesn't account for where fat is stored in the body, which also affects health risk. Waist circumference and other measures add useful context.
For a deeper clinical look at BMI, see the CDC's guide to Body Mass Index.
A few more tools people check alongside their BMI.