The most widely used unit system for BMI calculation worldwide is the metric system — kilograms (kg) for weight and centimetres (cm) for height. Whether you are in the UK, Canada, Australia, Pakistan, India, or most of Europe, you likely measure your weight in kg and your height in cm. Our free BMI Calculator is built for exactly this — instant, accurate BMI calculation using metric units.
The Body Mass Index formula using metric units is straightforward:
Notice that height must be in metres, not centimetres. So if you are 170 cm tall, you convert to 1.70 m first, then square it: 1.70 × 1.70 = 2.89. If you weigh 70 kg, your BMI is 70 ÷ 2.89 = 24.2.
Our calculator does this conversion automatically — just enter your height in cm and weight in kg and the result appears instantly.
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Malnutrition, weak immunity |
| 18.5 – 24.9 | Normal / Healthy Weight | Low risk ✅ |
| 25.0 – 29.9 | Overweight | Increased health risk |
| 30.0 – 34.9 | Obese Class I | High risk |
| 35.0 – 39.9 | Obese Class II | Very high risk |
| 40.0 and above | Obese Class III | Extremely high risk |
| Height (cm) | Weight (kg) | BMI | Category |
|---|---|---|---|
| 160 cm | 50 kg | 19.5 | Normal |
| 165 cm | 60 kg | 22.0 | Normal |
| 170 cm | 70 kg | 24.2 | Normal |
| 170 cm | 80 kg | 27.7 | Overweight |
| 175 cm | 90 kg | 29.4 | Overweight |
| 175 cm | 100 kg | 32.7 | Obese I |
| 180 cm | 75 kg | 23.1 | Normal |
| 180 cm | 95 kg | 29.3 | Overweight |
📏 Quick tip: Not sure of your height in cm? 5 feet = 152 cm, 5'5" = 165 cm, 5'9" = 175 cm, 6 feet = 183 cm. Our calculator also has an Imperial mode if you prefer feet and pounds.
A healthy BMI falls between 18.5 and 24.9. For a person who is 170 cm tall, this means a healthy weight range of approximately 53 to 72 kg. For someone who is 175 cm, the healthy range is approximately 57 to 76 kg. Our BMI Calculator shows your personal ideal weight range based on your exact height.
While BMI is a useful screening tool, it does have limitations. It does not distinguish between fat and muscle mass, so a very muscular person may have a high BMI despite being extremely fit and healthy. It also does not account for where fat is stored in the body — abdominal fat carries higher health risks than fat stored in the hips or thighs.
BMI is best used as one of several indicators of health, alongside waist circumference, diet, physical activity levels, and regular medical check-ups.
According to the World Health Organisation, a BMI between 18.5 and 24.9 is considered healthy for adults. However, different ethnic groups may have slightly different healthy ranges — for example, health guidelines for South Asian populations sometimes use a lower overweight threshold of 23.0.
The standard BMI formula is the same for men and women. However, women naturally have a higher percentage of body fat than men at the same BMI — so some health professionals use adjusted interpretations. Our calculator uses the universal WHO standard.
Most health guidelines recommend checking your BMI once every few months if you are trying to lose or gain weight, or once or twice a year for general health monitoring. Our calculator is completely free and available anytime — no signup needed.
Free, instant BMI calculation in metric units. Find your category and ideal weight range.
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