A better picture than BMI alone
BMI & Waist-to-Height Calculator
Work out your body mass index and your waist-to-height ratio, a simple measure that often says more about heart and metabolic health.
How to use it
How to use the BMI calculator
Step 1
Choose US or metric units.
Step 2
Enter your height, weight and, if you can, your waist measured around your belly button.
Step 3
See your BMI category and waist-to-height ratio.
How it works
How BMI and waist-to-height ratio are calculated
Body mass index
Weight in kilograms divided by height in meters squared. If you use feet and pounds, the calculator converts them first.
A worked example
Someone 5 feet 7 inches (1.70 m) who weighs 160 lb (72.6 kg) has a BMI of about 25.1.
Waist-to-height ratio
Your waist divided by your height, in the same units. A 34-inch waist and a 67-inch height give 0.51.
Measuring your waist
Stand relaxed, breathe out gently and measure around your belly button, with the tape level and snug.
Understanding your result
What your numbers mean
The calculator uses CDC adult BMI categories and widely used waist-to-height ranges.
| BMI | Category for adults |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to 24.9 | Healthy weight range |
| 25 to 29.9 | Overweight |
| 30 to 34.9 | Obesity, class 1 |
| 35 to 39.9 | Obesity, class 2 |
| 40 or higher | Obesity, class 3 |
| Waist-to-height | What it suggests |
|---|---|
| Under 0.5 | Lower risk range |
| 0.5 to 0.59 | Increased risk |
| 0.6 or higher | High risk |
A simple goal: keep your waist under half your height.
BMI has limits. It does not measure muscle, bone or where weight is carried. Very muscular people can score high, and some people carry risky belly fat at a normal BMI. Health risk can start at a lower BMI for people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean family background. These adult categories do not apply in pregnancy or to children and teens.
Next steps
When to talk to a clinician about weight
A BMI of 30 or more, or a waist-to-height ratio of 0.5 or more, is a good reason to check blood pressure, blood sugar and cholesterol. Medical weight management
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Practical, seasonal health tips and reminders from our nurse practitioner, about once or twice a month.
Keep exploring
Related pages and reading
Sources
- Adult BMI categories CDC
- Body mass index MedlinePlus
- Aim for a healthy weight NHLBI, NIH
- Overweight and obesity management (NG246) NICE
Common questions
About this tool
General information, not a diagnosis. For an emergency, call 911.
BMI is a quick screen but does not measure muscle or where weight is carried. Waist-to-height ratio adds useful context.
Keeping your waist under half your height (a ratio below 0.5) is a good general goal.
Around your belly button, standing relaxed, after breathing out gently, with the tape level all the way around.
No. Children and teens are assessed with BMI percentiles for age and sex, so ask your clinician.
Yes. Medical weight management, including GLP-1 medicines when appropriate, can be handled largely by video, with labs drawn near you.
Ready when you are