BMI Calculator
Use this free BMI Calculator to check your Body Mass Index based on height and weight. Choose your preferred units: weight in kg or lb, height in cm, m, or ft & in. See your BMI value and category to understand whether your current weight is in a healthy range.
Calculate Your BMI
BMI Results
Body Mass Index is a simple way to screen weight relative to height. Always talk to a health professional for a complete assessment.
How BMI Is Calculated
BMI (Body Mass Index) is a value that uses your weight and height to estimate if your weight is in a range that is typically associated with a lower risk of certain health problems. It is a widely used screening tool for adults.
BMI Formula (Metric)
BMI = weight (kg) ÷ [height (m)]²
- Weight: Body weight in kilograms (or convert from pounds: lb ÷ 2.205)
- Height: Height in meters (or convert from cm ÷ 100, or from feet/inches)
Typical BMI Categories (Adults)
- Underweight: BMI below 18.5
- Normal weight: BMI from 18.5 to 24.9
- Overweight: BMI from 25 to 29.9
- Obesity: BMI 30 and above
BMI Example
Example
Weight = 70 kg, Height = 170 cm (1.70 m)
BMI = 70 ÷ (1.70 × 1.70) ≈ 24.2
This BMI falls in the “Normal weight” range.
Quick Answers
What is BMI?
BMI (Body Mass Index) is a value derived from weight and height used to categorise underweight, normal weight, overweight, and obesity in adults.
How is BMI calculated?
BMI = weight in kg ÷ (height in metres)². For example, 70 kg and 1.70 m gives BMI = 70 ÷ 2.89 ≈ 24.2.
What are the standard BMI categories for adults?
Underweight: below 18.5; Normal: 18.5–24.9; Overweight: 25–29.9; Obesity: 30 and above.
Does BMI apply to children?
BMI for children is interpreted using age- and sex-specific charts; adult categories do not apply. This calculator is for adults.
Is BMI the same as body fat?
No. BMI is a screening tool based only on height and weight. It does not measure body fat or distinguish muscle from fat.
Frequently Asked Questions
Can I use pounds and feet for weight and height?
Yes. This BMI calculator supports multiple units: weight in kg or lb, and height in cm, m, or ft & in. Choose your preferred units from the dropdowns; the result is the same.
Is BMI the same as body fat percentage?
No. BMI uses only height and weight. Body fat percentage requires more detailed measurements or devices.
Is BMI reliable for everyone?
BMI is a general screening tool. It may not fully reflect health status for athletes, older adults, or people with very high muscle mass.
Should I try to reach a “perfect” BMI?
Use BMI as one signal, not a final goal. Focus on healthy habits like balanced food, movement, sleep, and stress management.
Can I use this BMI calculator for children?
BMI for children uses age- and sex-specific growth charts. This calculator is for adults. Always ask a pediatric professional for advice about children.
Does BMI work the same way for men and women?
The BMI formula is the same for men and women, but body fat and health risks can differ by sex. Use BMI as a starting point and speak with a health professional for advice that fits your own body.
What should I do if my BMI is high or low?
Speak with a qualified health professional. They can look at your full health picture and guide you on safe next steps.
Is this BMI calculator free to use?
Yes. You can use this tool as many times as you like without signing up.