BMI Calculator for Adults (Pounds & Feet)
BMI is weight relative to height: 703 x your weight in pounds divided by your height in inches squared. For adults, 18.5 to 24.9 is the healthy range. Enter your height and weight below.
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This BMI calculator finds your body mass index from your height and weight and places it in the adult categories used by the NIH National Heart, Lung, and Blood Institute: under 18.5 underweight, 18.5 to 24.9 healthy, 25.0 to 29.9 overweight and 30.0 or above obesity.
The formula in US units is BMI = 703 x weight (lb) / height (in)². In metric, it's weight (kg) / height (m)². For example, someone who is 5'9" (69 inches) and 160 lb has a BMI of 703 x 160 / 69² = 23.6. The calculator handles both units, so you can switch with one tap.
BMI is popular because it's quick, free and consistent, which makes it useful in research and as a first-pass screening number. It doesn't measure body fat directly. Muscular people can score high, it doesn't show where weight is carried, and it uses the same cut-offs for men and women.
For a fuller picture, pair BMI with waist measurement, how your clothes fit, your energy levels and your training progress. Our BMR and TDEE calculator and protein calculator help turn the number into a practical daily plan.
How it works
BMI compares weight to height. The math: BMI = 703 x pounds / inches squared, or kg / meters squared.
It's a fast screening number used in research and checkups. It doesn't measure body fat directly, so muscular people can score high, and it says nothing about where weight is carried.
What the research says
- NIH NHLBI adult categories: under 18.5 underweight, 18.5 to 24.9 healthy, 25.0 to 29.9 overweight, 30.0 or above obesity. Read the study
Glossary
- BMI
- Body mass index: weight relative to height squared.
- Screening tool
- A quick first-pass measure, not a diagnosis.
- Body composition
- The split between fat, muscle, bone and water.
Frequently asked questions
How do I calculate my BMI?
Multiply your weight in pounds by 703, then divide by your height in inches squared. In metric, divide weight in kg by height in meters squared.
What is a healthy BMI for adults?
NIH categories list 18.5 to 24.9 as the healthy range for adults, under 18.5 as underweight, 25.0 to 29.9 as overweight and 30.0 or above as obesity.
Is BMI accurate for muscular people?
BMI doesn't distinguish muscle from fat, so very muscular people can have a high BMI with low body fat.
Is BMI different for men and women?
The adult BMI formula and categories are the same for men and women.
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- NIH National Heart, Lung, and Blood Institute. Calculate Your BMI (BMI categories). https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm
For information only, not medical advice.