BMI Calculator
The bmi calculator helps you calculate your Body Mass Index (BMI) to see if you are in a healthy weight range.. Enter your physiological measurements to review benchmark metrics aligned with health guidelines.
Your BMI
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How the BMI Calculator Works
Last updated: October 2026This calculator uses the international standard BMI formula: BMI = weight (kg) ÷ height (m)². Enter height and weight to receive your BMI score benchmarked against NHS adult weight categories: Underweight (<18.5), Healthy (18.5–24.9), Overweight (25–29.9), Obese (30+).
Inputs & Output Metrics
Required Input Parameters
- Body Weight & Height
- Age & Biological Sex
- Target Activity Level
Calculated Output Results
- Calculated Index / Benchmark Score
- Target Healthy Range
- Category Status Classification
BMI Calculator Worked Calculation Example
Height: 175 cm (1.75 m)
Weight: 70 kg
BMI = 22.86 kg/m² (Healthy Weight)
Explanation: 70 kg divided by (1.75 m × 1.75 m) = 70 / 3.0625 = 22.86 BMI.
Assumptions & Limitations
Model Assumptions
- Assumes standard physiological reference standards for healthy adults.
- Calculations rely on clinically published population formulas.
Real-World Limitations
- Not a substitute for professional clinical diagnosis or medical advice.
- Does not account for specific medical conditions, pregnancy, or high muscle mass.
Frequently Asked Questions
What is a healthy BMI range for adults?
According to NHS guidelines, a healthy BMI for adults is between 18.5 and 24.9. Below 18.5 is classified as underweight, 25 to 29.9 is overweight, and 30 or above is classified as obese.
Is BMI an accurate measure of health for adults?
BMI is a useful screening tool but does not directly measure body fat distribution or muscle mass. Athletes often have a high BMI due to muscle. It is best evaluated alongside waist circumference.
How do I manually calculate my BMI?
Divide your weight in kilograms by your height in metres squared. For example, 75 kg divided by (1.75 m × 1.75 m) = 75 ÷ 3.0625 = 24.5 BMI.
Does BMI use different thresholds for men and women?
The standard BMI formula and adult weight thresholds are identical for men and women.
What BMI is classified as obese?
A BMI of 30 or above is classified as obese. A BMI of 40 or above is classified as severely (morbidly) obese.
Disclaimer: This tool is intended for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your GP or healthcare provider.