BMI Calculator: Check Your Body Mass Index
Calculate your Body Mass Index from height and weight, with BMI category and healthy weight range for adults.
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy
BMI Calculator: Check Your Body Mass Index Formula
BMI = weight (kg) / height (m)^2
BMI compares body weight with height. In metric units, divide weight in kilograms by height in meters squared. In imperial units, use BMI = [weight in lbs x 703] / [height in inches]^2.
BMI Calculator: Check Your Body Mass Index — Worked Examples
Example 1: Normal BMI Calculation
Problem:Calculate BMI for a 35-year-old male who is 5'10\" (178 cm) and weighs 170 lbs (77 kg).
Solution:Height in meters = 178 / 100 = 1.78 m\nWeight in kg = 170 x 0.4536 = 77.1 kg\nBMI = 77.1 / (1.78)^2 = 24.3\nCategory: Normal Weight\nIdeal weight range: about 129 to 173 lbs
Result:BMI: 24.3 - Normal Weight | Health Risk: Low
Example 2: Obese BMI Calculation
Problem:Calculate BMI for a 45-year-old female who is 5'4\" (163 cm) and weighs 200 lbs (91 kg).
Solution:Height in meters = 163 / 100 = 1.63 m\nWeight in kg = 200 x 0.4536 = 90.7 kg\nBMI = 90.7 / (1.63)^2 = 34.1\nCategory: Obese Class I (30-34.9)\nIdeal weight range: about 107 to 144 lbs\nWeight to lose for normal BMI: about 56 lbs
Result:BMI: 34.1 - Obese Class I | Increased risk of type 2 diabetes and cardiovascular disease
Example 3: Underweight BMI Calculation
Problem:Calculate BMI for a 22-year-old female who is 5'7\" (170 cm) and weighs 105 lbs (48 kg).
Solution:Height in meters = 170 / 100 = 1.70 m\nWeight in kg = 105 x 0.4536 = 47.6 kg\nBMI = 47.6 / (1.70)^2 = 16.5\nCategory: Severe Thinness (below 16)\nIdeal weight range: about 121 to 163 lbs\nWeight to gain for normal BMI: about 16 lbs
Result:BMI: 16.5 - Severe Thinness | Health Risk: Very High
BMI Calculator: Check Your Body Mass Index — Frequently Asked Questions
What is BMI and what does it measure?
BMI, or Body Mass Index, is a screening tool that compares weight and height. It is useful for broad health screening, but it does not directly measure body fat.
What is a healthy BMI range?
For most adults, a BMI from 18.5 to 24.9 is considered a healthy range. Lower values indicate underweight status, while higher values move into overweight and obesity ranges.
What are the limitations of BMI?
BMI does not separate fat from muscle, does not show where body fat is stored, and does not fully account for age, sex, ethnicity, or athletic build. It works best alongside other health measures.
Is BMI accurate for children?
Adult BMI ranges are not used for children and teens. Younger users need age- and sex-specific BMI percentile charts, which is why child and teen BMI tools are handled separately.