Calculate your BMI and turn it into a practical health plan.

Switch between metric and US units, get your BMI, see a healthy weight range, and read tailored guidance for your category — all in one place.

Typical time

Under 30 seconds

Recommended for

Adults aged 18–65

Outputs

BMI, range, ideal weight, BMI Prime & Ponderal Index

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Adults only. For children and teenagers, healthcare providers use age- and sex-specific BMI charts.

Gender

BMI scale (10–40)

1018.5253040
UnderweightNormalOverweightObese

What BMI indicates

BMI compares weight to height to estimate whether body mass is in a range broadly associated with lower health risk. It does not directly measure body fat or account for muscle mass, bone density, or fat distribution.

Categories

  • Underweight: potential nutrient deficiency or other concerns.
  • Normal: generally associated with lower chronic disease risk.
  • Overweight: higher risk of metabolic and cardiovascular conditions.
  • Obese: substantially increased risk; medical guidance recommended.

Beyond BMI

Use BMI alongside waist circumference, physical activity, family history, and clinical measures. BMI Prime contextualises BMI relative to the upper healthy threshold, while the Ponderal Index considers height cubed to better reflect proportionality in taller or shorter individuals.

This calculator is for educational use and does not replace personalised medical advice, diagnosis, or treatment.

What is Body Mass Index (BMI)?

Body Mass Index (BMI) is a simple calculation using a person's height and weight. The formula is BMI = kg/m2 where kg is a person's weight in kilograms and m2 is their height in metres squared.

A BMI of 25.0 or more is overweight, while the healthy range is usually 18.5 to 24.9. BMI applies to most adults 18-65 years.

Understanding Your BMI Result

BMI Range Category
Below 18.5Underweight
18.5 – 24.9Normal Weight
25.0 – 29.9Overweight
30.0 and AboveObesity

How is BMI Calculated?

The formula is straightforward:

BMI = Weight (kg) / (Height (m))2

For example, if you weigh 70kg and are 1.75m tall:
70 / (1.75 * 1.75) = 22.86 (Normal Weight)

Limitations of BMI

While BMI is a useful screening tool, it does not diagnose the body fatness or health of an individual. It has some limitations:

  • Muscle Mass: Athletes with high muscle mass may have a high BMI but not be overweight.
  • Age: Older adults may have more body fat than younger adults with the same BMI.
  • Distribution: It doesn't account for where fat is stored (belly fat is riskier).

Frequently Asked Questions (FAQ)

Is BMI accurate for everyone?
No. It is a general indicator. It may not be accurate for athletes, pregnant women, and the elderly.
What is a healthy BMI for women vs men?
The standard BMI categories are the same for both men and women. However, women naturally have more body fat than men.