BMI Calculator

Body mass index (BMI) is weight in kilograms divided by height in metres squared. It is a quick screening number for adults, not a diagnosis. This BMI calculator accepts metric or imperial units, shows the calculation step by step, gives the standard adult category, and works out the healthy weight range for your height.

Try:

How to use the bmi calculator

  1. Choose metric or imperial units.
  2. Enter weight and height.
  3. Press Calculate to see your BMI, category and healthy range.

Formula

BMI=mass (kg)height (m)2\text{BMI} = \frac{\text{mass (kg)}}{\text{height (m)}^2}

Worked example: 70 kg, 175 cm

  • Units: Metric (kg, cm)
  • Weight (kg): 70
  • Height (cm): 175

✓ Answer checked

BMI≈22.86\text{BMI} \approx 22.86
Category (adults)
Healthy weight
Healthy weight range for this height
56.66 kg – 76.26 kg
0102030Under 18.5: 18.5Under 18.518.5–24.9: 24.918.5–24.925–29.9: 29.925–29.930+: 3530+your BMI 22.86
Adult BMI bands; the highlighted band contains your BMI.
Step-by-step working (2 steps)

  1. Height in metres

    Divide centimetres by 100.

    175 cm=1.75 m175\text{ cm} = 1.75\text{ m}

  2. Apply the formula BMI = kg ÷ m²

    Weight in kilograms divided by height in metres squared.

    BMI=701.752≈22.8571\text{BMI} = \frac{70}{1.75^2} \approx 22.8571
Formulas used
BMI=mass (kg)height (m)2\text{BMI} = \frac{\text{mass (kg)}}{\text{height (m)}^2}
How this was checked
  • ✓ BMI × height² gives back the weight.

BMI is a rough screening measure for adults and does not account for muscle, age, sex or ethnicity. It is not medical advice.

Frequently asked questions

What is a healthy BMI?

For most adults, 18.5 to 24.9 is considered a healthy range.

Is BMI accurate for everyone?

No. It does not separate muscle from fat and may not suit children, athletes, older adults or all ethnic groups. Ask a health professional for advice.

How is BMI calculated in pounds and inches?

Convert to kilograms and metres, or use BMI = 703 × pounds ÷ inches².

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