BMI Calculator - Calculate Your Body Mass Index Free BMI Calculator
Use our free BMI calculator to check your Body Mass Index. Enter your height and weight in metric or imperial units and instantly see your BMI category.
Your Measurements
Your Results
<18.5 Normal
18.5–24.9 Overweight
25–29.9 Obese
≥30
BMI Classification Male
| Category | BMI Range |
|---|---|
| Severe Thinness | < 16 |
| Moderate Thinness | 16 – 16.9 |
| Underweight | 17 – 18.4 |
| Normal Weight | 18.5 – 24.9 |
| Overweight | 25 – 29.9 |
| Obese Class I | 30 – 34.9 |
| Obese Class II | 35 – 39.9 |
| Obese Class III | ≥ 40 |
BMI Calculator - Guide
What is BMI?
BMI (Body Mass Index) is a simple numerical value derived from your weight and height. It is widely used by health professionals as a quick screening tool to categorise individuals into weight classes — underweight, normal weight, overweight, or obese. While BMI does not measure body fat directly, it correlates reasonably well with more precise methods of body fat measurement.
BMI Calculation Formula
BMI = Weight (kg) ÷ [Height (m)]²
Example:
- Height = 170 cm = 1.70 m
- Weight = 70 kg
- BMI = 70 ÷ (1.70 × 1.70) = 70 ÷ 2.89 = 24.2
BMI Categories (WHO Standard)
- Underweight: BMI less than 18.5 — May indicate nutritional deficiency or underlying health issues.
- Normal Weight: BMI 18.5 to 24.9 — Associated with the lowest health risk.
- Overweight: BMI 25 to 29.9 — Increased risk of cardiovascular disease, diabetes, and other conditions.
- Obese: BMI 30 or above — Significantly elevated risk of serious health conditions.
Gender & BMI
Research shows that body fat distribution differs between males and females. Women naturally carry a higher percentage of body fat than men at the same BMI value. Consequently, the “ideal” body-fat-based BMI ranges have slight gender-specific variations:
- Men: Normal BMI 18.5 – 24.9. A healthy body fat percentage ranges from 10 – 20%.
- Women: Normal BMI 18.5 – 24.9 (same WHO cut-off), but optimal ranges may centre slightly higher. Healthy body fat percentage ranges from 20 – 30%.
Our calculator uses gender-aware interpretation to provide more context-specific advice alongside the standard WHO categories.
Limitations of BMI
- Muscle Mass: Athletes with high muscle mass may have a high BMI despite low body fat.
- Age & Gender: While our calculator adjusts interpretation for gender, BMI remains an imperfect measure of individual health.
- Ethnicity: Health risk thresholds may differ across ethnic groups; some populations face higher risk at lower BMI values.
- Body Composition: BMI cannot distinguish between fat, muscle, bone, and water mass.
BMI is a useful starting point, but it should be used alongside other measurements (waist circumference, body fat percentage) and professional medical advice.
How Our BMI Calculator Works
- Gender: Select Male or Female for gender-specific interpretation of your results.
- Height: Enter your height in centimetres or switch to feet & inches.
- Weight: Enter your weight in kilograms or switch to pounds.
- Instant Results: Your BMI value, category, and colour-coded gauge update in real time.
- Healthy Range: See the healthy weight range for your height based on BMI 18.5–24.9.