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BMI & Calories
BMI & Calorie Calculator — body mass index and daily needs
This calculator finds your Body Mass Index (BMI) from height and weight, shows the weight category, and estimates the calories you burn per day. Switch between metric and imperial units.
How BMI and calories are calculated
BMI is weight in kilograms divided by height in metres squared. Daily calories use the Mifflin-St Jeor equation for your resting metabolism, multiplied by an activity factor from sedentary to very active.
BMI categories (WHO)
The World Health Organization groups adult BMI into these bands:
| Category | BMI (kg/m²) |
|---|---|
| Underweight | below 18.5 |
| Healthy weight | 18.5 – 24.9 |
| Overweight (pre-obesity) | 25.0 – 29.9 |
| Obesity class I | 30.0 – 34.9 |
| Obesity class II | 35.0 – 39.9 |
| Obesity class III | 40.0 and above |
Source: World Health Organization classification (World Obesity Federation).
Healthy weight range by height
Because BMI is weight ÷ height², a healthy BMI (18.5–24.9) maps to a weight range for each height. We computed the ranges below directly from that formula:
| Height | Healthy weight |
|---|---|
| 150 cm (4'11") | 41.6 – 56.0 kg |
| 155 cm (5'1") | 44.4 – 59.8 kg |
| 160 cm (5'3") | 47.4 – 63.7 kg |
| 165 cm (5'5") | 50.4 – 67.8 kg |
| 170 cm (5'7") | 53.5 – 72.0 kg |
| 175 cm (5'9") | 56.7 – 76.3 kg |
| 180 cm (5'11") | 59.9 – 80.7 kg |
| 185 cm (6'1") | 63.3 – 85.2 kg |
| 190 cm (6'3") | 66.8 – 89.9 kg |
| 195 cm (6'5") | 70.3 – 94.7 kg |
Not medical advice. BMI is a screening tool, not a diagnosis. It does not distinguish muscle from fat, and lower cut-offs are recommended for some populations (for example, many Asian groups). It is not used for under-18s or during pregnancy. For any health decision, consult a qualified professional.
BMI for different people
BMI uses the same formula for all adults, but it does not fit everyone equally. Very muscular people can read as overweight, while older adults may carry less muscle than the number suggests. For children and teenagers, doctors use age- and sex-specific percentiles instead.
Beyond BMI
Waist circumference and waist-to-height ratio add useful information about where fat is stored, which BMI alone cannot show. If your BMI is near a boundary, these extra measures give a fuller picture.
Example
A person 1.75 m tall weighing 68 kg has a BMI of 68 ÷ (1.75 × 1.75) = 22.2, which falls in the normal range.
Method and sources
BMI is weight in kilograms divided by height in metres squared, and the categories (under 18.5, 18.5–24.9, 25–29.9, 30+) follow the World Health Organization. Daily calories use the Mifflin-St Jeor equation for resting metabolism, multiplied by an activity factor. BMI is a screening guide, not a diagnosis, and it does not separate muscle from fat — for health decisions, speak to a professional.
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FAQ
How is BMI calculated?
Weight in kilograms divided by height in metres squared. 70 kg at 1.75 m gives a BMI of 22.9.
What is a healthy BMI range?
18.5–24.9 is considered normal; below is underweight, 25–29.9 overweight and 30+ obese.
Is BMI accurate for everyone?
No — it ignores muscle and build, so athletes may read high. Use it as a rough guide, not a diagnosis.