BMI Calculator
Calculate your body mass index (BMI) with your weight and height. Indicative; does not replace medical advice.
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BMI is indicative. It does not account for muscle mass or age. Consult a health professional. Need web development? Get a quote.
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Quick demo: how to use this tool
- Enter your weight in kilograms and your height in centimeters.
- Press calculate to see your BMI and the category (underweight, normal, overweight, obese).
- Share the result or try another measurement without reloading the page.
What BMI is and how to read it
Body mass index (BMI) compares your weight with your height: BMI = weight (kg) ÷ height (m)², or 703 × weight (lb) ÷ height (in)² in US units. This calculator works in kilograms and centimetres or in pounds, feet and inches, shows your category and tells you the weight range that corresponds to a normal BMI for your height.
BMI categories for adults (WHO)
| BMI | Category |
|---|---|
| Below 16 | Severe thinness |
| 16 – 16.9 | Moderate thinness |
| 17 – 18.4 | Mild thinness (underweight) |
| 18.5 – 24.9 | Normal weight |
| 25 – 29.9 | Overweight |
| 30 – 34.9 | Obesity class I |
| 35 – 39.9 | Obesity class II |
| 40 or more | Obesity class III |
Healthy weight range by height
| Height | Weight at BMI 18.5 | Weight at BMI 24.9 |
|---|---|---|
| 5' 0" (152 cm) | 95 lb (43 kg) | 127 lb (58 kg) |
| 5' 3" (160 cm) | 104 lb (47 kg) | 141 lb (64 kg) |
| 5' 6" (168 cm) | 115 lb (52 kg) | 154 lb (70 kg) |
| 5' 9" (175 cm) | 125 lb (57 kg) | 169 lb (76 kg) |
| 6' 0" (183 cm) | 136 lb (62 kg) | 184 lb (83 kg) |
| 6' 3" (190 cm) | 148 lb (67 kg) | 199 lb (90 kg) |
What BMI cannot tell you
- Muscle versus fat. Athletes and people with a lot of muscle can have a high BMI without excess body fat.
- Where fat is stored. Belly fat carries more health risk than fat on the hips; waist circumference or waist-to-height ratio adds that information.
- Age, sex and ethnicity. Older adults tend to carry more fat at the same BMI, and for people of Asian descent health risks rise at lower BMI values (the WHO suggests extra attention from about 23).
- Children and teens. They are assessed with BMI-for-age percentiles, not with these adult cut-offs. Pregnancy also needs a different approach.
Treat BMI as a screening number, not a diagnosis. If your result is outside the normal range, a doctor or dietitian can look at blood tests, body composition and lifestyle to give you advice that fits you.
BMI interpretation table (WHO)
| Category | BMI (kg/m²) | Associated risk |
|---|---|---|
| Underweight | Below 18.5 | Nutritional risk |
| Normal weight | 18.5 – 24.9 | Low risk (reference range) |
| Overweight | 25.0 – 29.9 | Mild to moderate risk |
| Obesity class I | 30.0 – 34.9 | High risk |
| Obesity class II | 35.0 – 39.9 | Very high risk |
| Obesity class III | 40.0 or more | Extremely high risk |
Source: standard WHO classification for the adult population. These ranges are the same for men and women, though at the same BMI women tend to carry more body fat and men more muscle mass — so BMI is a general guide, not an individual diagnosis.
How to use BMI Calculator
- Enter your weight in kilograms in the corresponding field.
- Enter your height in centimeters (or meters, depending on the form).
- Click Calculate BMI to see your index with the WHO category (underweight, normal, overweight, or obesity).
- Compare your result with the WHO interpretation table above.
BMI calculator FAQ
How do I calculate BMI in pounds and inches?
Multiply your weight in pounds by 703 and divide by your height in inches squared. At 154 lb and 67 in: 154 × 703 ÷ 4,489 = 24.1, which is normal weight.
What is a healthy BMI?
For adults, a BMI from 18.5 to 24.9 is classed as normal weight. 25 to 29.9 is overweight and 30 or more is obesity.
Is BMI accurate for athletes?
Not always. BMI does not separate muscle from fat, so a muscular person can score as overweight. Body-fat percentage or waist measurements give a better picture.
Is the BMI the same for men and women?
The adult cut-offs are the same, but body composition differs: at the same BMI women usually carry more body fat than men.
Can I use this calculator for my child?
No. Children and teenagers are assessed with BMI-for-age percentiles that depend on age and sex. Ask a paediatrician.
How often should I check my BMI?
Every few months, or after a significant change in weight. Small day-to-day fluctuations are not meaningful.