BMI Calculator

Body Mass Index in metric or imperial units, with WHO category and healthy weight range for your height.

cm
lb
ft
in
Enter your details and press Calculate to see results.

Formula

BMI = weight(kg) ÷ height(m)² · Imperial: 703 × lb ÷ in²

Example

70 kg at 1.75 m → 70 ÷ (1.75 × 1.75) = 22.86, comfortably inside the healthy range.

Understanding your category

The World Health Organization classifies adults as underweight (below 18.5), healthy (18.5–24.9), overweight (25–29.9) and obese (30+). The bands are broad screening tools, not diagnoses.

What BMI misses

BMI cannot distinguish muscle from fat, so athletes often register 'overweight' despite low body fat. It also shifts with age and ethnicity. Pair it with body-fat percentage or waist measurement for a fuller picture.

For anyone under 20, BMI must be compared against age-and-sex percentile charts rather than adult cutoffs — this calculator is intended for adults.

Frequently asked questions

Is BMI accurate?

It's a reasonable population-level screen but individual accuracy varies, especially for muscular people, older adults and different ethnic groups.

What BMI should I aim for?

Most guidance points at the 18.5–24.9 band, but personal targets depend on body composition and health markers — discuss specifics with a clinician.

How do I calculate BMI in pounds and inches?

Multiply pounds by 703, divide by height in inches squared. Switch the unit toggle above to do it automatically.

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