How is BMI calculated?

BMI = weight(kg) / height(m)². For example, 70kg at 1.75m = 22.86 BMI.

Does BMI apply to children?

No. Children use BMI-for-age percentiles. This calculator is for adults aged 18+.

Health Calculator

BMI Calculator

Calculate your Body Mass Index instantly. Enter your height and weight to see your BMI score and health category.

ℹ️ This calculator is for adults aged 18 and over. Results are for informational purposes only.

Height (cm) Range: 50–300 cm

Weight (kg) Range: 10–300 kg

Your BMI Result

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What Is BMI and Why Does It Matter?

Body Mass Index (BMI) is a simple screening tool used by healthcare professionals worldwide to assess whether a person's weight is appropriate for their height. Calculated using your weight in kilograms divided by the square of your height in metres, BMI provides a quick, cost-free estimate of body fatness that correlates with risk of chronic diseases.

BMI Formula

BMI = Weight (kg) ÷ Height (m)²

Example: A person weighing 70 kg with a height of 1.75 m has a BMI of 70 ÷ (1.75 × 1.75) = 22.86 — squarely in the Normal range.

BMI Categories (WHO Standard)

Underweight (BMI < 18.5): May indicate nutritional deficiency or underlying illness. A doctor's evaluation is recommended.
Normal weight (18.5–24.9): Associated with the lowest risk of weight-related health problems.
Overweight (25–29.9): Increased risk of cardiovascular disease, type 2 diabetes, and joint problems.
Obese (≥30): Significantly elevated risk of serious conditions including heart disease, stroke, and certain cancers.

Limitations of BMI

BMI does not distinguish between fat and muscle mass — highly trained athletes may register as overweight. It also doesn't account for age, sex, ethnicity, or fat distribution. Always interpret BMI alongside lifestyle factors and consult a qualified healthcare professional for personalized advice.

Who Should Use This Calculator?

This BMI calculator is designed for adults aged 18 and over. For children and teenagers, paediatricians use BMI-for-age percentile charts. Pregnant women should not use standard BMI calculations during pregnancy.

Frequently Asked Questions

What is a healthy BMI for adults?

For most adults aged 18–65, a healthy BMI falls between 18.5 and 24.9. This range is associated with the lowest risk of weight-related health conditions according to WHO guidelines. Athletes or those with high muscle mass may have a higher BMI while still being in excellent health.

Is BMI the same for men and women?

The formula and category thresholds are identical for both sexes. However, women naturally carry a higher proportion of body fat at any given BMI. Some clinicians use sex-adjusted interpretations, but the WHO scale applies universally as a first-pass screening tool.

How often should I check my BMI?

Most health professionals recommend checking BMI every 6–12 months as part of a regular health review. More frequent checks are useful when actively trying to lose or gain weight, ideally tracking alongside other metrics like waist circumference.

What should I do if my BMI is outside the healthy range?

If your BMI is below 18.5 or above 24.9, consider consulting a GP or registered dietitian for personalized guidance. Small, sustainable changes to diet and physical activity are generally more effective than rapid interventions.

Is this BMI calculator free?

Yes — completely free with no account required. Your height and weight data is used only for the calculation and is never stored, logged, or shared.

BMI Calculator

What Is BMI and Why Does It Matter?

BMI Formula

BMI Categories (WHO Standard)

Limitations of BMI

Who Should Use This Calculator?

Frequently Asked Questions

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