BMI Calculator
Enter your height and weight to get your body mass index, the healthy weight range for your height, and a clear explanation of what the number means.
Quick answer: BMI is your weight in kilograms divided by your height in meters squared. For adults, 18.5 to 24.9 is the normal range, 25 to 29.9 is overweight, and 30 and above is obese. The calculator above does the math for you in either metric or US units.
Enter your height and weight, then press Calculate.
- Healthy weight range—
- To reach a healthy weight—
- BMI Prime—
BMI is a screening tool, not a diagnosis. It does not measure body fat directly, and it reads high for muscular people and low for some older adults.
What your BMI number means
The World Health Organization cut-offs below apply to adults age 20 and older. They are the same numbers most US doctors and insurance plans use.
| BMI | Category | What it means |
|---|---|---|
| Below 18.5 | Underweight | You may need to gain weight. Talk to a doctor if this is not intentional. |
| 18.5 – 24.9 | Normal weight | The range linked to the lowest risk of weight-related disease for most adults. |
| 25.0 – 29.9 | Overweight | Carries a higher risk of type 2 diabetes and heart disease for some people. |
| 30.0 and above | Obese | Carries a clearly higher risk of several chronic conditions. |
More than one number
BMI is a starting point, not a verdict. These tools put it in context.
Calorie Calculator
Find out how many calories you burn a day and how many to eat for your goal.
Read more →Body Fat Calculator
Estimate your body fat percentage from BMI, age and sex.
Read more →Healthy Weight Range
See the healthy weight range for your exact height, in pounds and kilograms.
Read more →How to use the BMI calculator
1. Pick your units
US units are selected by default, so you can enter your height in feet and inches and your weight in pounds. Switch to Metric if you think in centimeters and kilograms.
2. Enter your numbers
Use your height without shoes and your weight first thing in the morning for the most consistent reading. Weight fluctuates by a few pounds over the course of a day, so compare like with like.
3. Read the result carefully
The calculator shows your BMI, the category, the healthy weight range for your height, and how many pounds separate you from it. That last figure is usually the most useful one.
What BMI does not measure
- Body fat versus lean muscle mass
- Where your body stores fat, which matters more than the total
- Cardiovascular fitness, blood pressure or blood sugar
- Differences between ethnic groups at the same BMI
- Whether you are pregnant, an athlete or over 65
Treat the number as one data point among several. Waist circumference, resting heart rate, lab work and how you actually feel all carry information that BMI cannot.
Frequently asked
Is BMI accurate for everyone?
No. BMI was designed for population studies, not for individuals. It overestimates risk for muscular people and athletes, and it underestimates risk for adults who have lost muscle with age. It is a useful first screen because it costs nothing and needs only a tape measure and a scale.
What is a healthy BMI?
For most adults age 20 and older, a BMI between 18.5 and 24.9 is considered healthy. Some researchers argue the upper limit should be closer to 25 for people of European descent and lower for people of Asian descent, who tend to develop weight-related conditions at a lower BMI.
Do I use the same BMI scale as a child?
No. Children and teens are measured against growth charts that compare them with others of the same age and sex. See the kids BMI page for how that works.
Is BMI different in kilograms and pounds?
No. BMI is the same number in any unit system. The calculator converts your input before doing the math, so 160 lb at 5 ft 9 in gives exactly the same BMI as 72.6 kg at 175 cm.