BMI Calculator
Calculate your Body Mass Index (BMI) and Basal Metabolic Rate (BMR)
What is BMI?
Body Mass Index (BMI) is a simple measurement that uses your height and weight to estimate body fat. It is widely used by healthcare professionals as a screening tool to identify potential weight-related health risks.
BMI Formula
The BMI formula is: BMI = weight (kg) / height² (m²)
For imperial measurements: BMI = (weight in lbs × 703) / height² (in²)
BMI Categories
- Underweight: BMI less than 18.5
- Normal weight: BMI 18.5 to 24.9
- Overweight: BMI 25 to 29.9
- Obese: BMI 30 or greater
What is BMR?
Basal Metabolic Rate (BMR) is the number of calories your body needs at complete rest to maintain vital functions like breathing, circulation, and cell production. It represents about 60-75% of your daily calorie expenditure.
Mifflin-St Jeor Formula
Men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161
Reviewed by zurtool Health Team. Last updated: 2026.