BMI Calculator
Calculate your Body Mass Index (BMI) from your height and weight and see which category it falls into. Enter your weight and height and this calculator returns your BMI, its category, and the healthy weight range for your height.
- Standard adult BMI thresholds are used.
- Not a medical diagnosis — consult a healthcare professional for advice.
Formula
BMI = weight (kg) ÷ height (m)²
- BMI divides your weight in kilograms by the square of your height in metres.
- Standard adult categories: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30 and above obese.
- The healthy weight range shown is the weight that would put your BMI between 18.5 and 24.9 for your height.
- BMI is a quick screen, not a body-fat measurement — it can over- or under-estimate for athletes, older adults, and some ethnic groups.
- Use it as a starting point and discuss any concerns with a healthcare professional.
70 kg, 170 cm
Inputs
- Weight: 70 kg
- Height: 170 cm
BMI = 70 ÷ 1.70² = 24.2, which is in the normal-weight range. The healthy weight band for 170 cm is about 53.5–72 kg.
Frequently asked questions
How is BMI calculated?
BMI = weight (kg) ÷ height (m)². For example, 70 kg and 1.70 m gives 70 ÷ 2.89 = 24.2.
What is a healthy BMI?
For most adults a BMI between 18.5 and 24.9 is considered healthy. Below 18.5 is underweight and 25 or above is overweight or obese.
Is BMI accurate for everyone?
Not always. Because it ignores muscle, fat distribution, and frame, very muscular or older people may get misleading results.
Does BMI differ for men and women?
The formula and adult categories are the same, though body composition differs. For children and teens, age- and sex-specific percentiles are used instead.
How can I change my BMI?
Since height is fixed for adults, BMI changes with weight. Gradual, sustainable changes in diet and activity are the safest way to move toward a healthy range.
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