What is a healthy BMI?

For most adults, a BMI between 18.5 and 24.9 is classed as the normal range by the WHO. Below 18.5 is underweight, 25-29.9 is overweight, and 30 or above is obese.

How do I calculate BMI in pounds and inches?

Multiply your weight in pounds by 703, then divide by your height in inches squared. For example, 154 lb and 69 in: 703 x 154 / (69 x 69) = 22.7.

Does the calculator store my height and weight?

No. The BMI calculation runs entirely in your browser tab. Nothing you enter is uploaded or stored.

Guide1 min readUpdated July 8, 2026

How to calculate BMI

Short answer

BMI is your weight in kilograms divided by your height in metres squared (kg/m2). In imperial units, multiply pounds by 703 and divide by height in inches squared. A BMI of 18.5-24.9 is the standard 'normal' range.

The BMI formula

BMI (Body Mass Index) estimates body fatness from height and weight. It is the same number worldwide, just calculated in metric or imperial units.

Metric:    BMI = weight(kg) / height(m)^2
Imperial:  BMI = 703 * weight(lb) / height(in)^2

Metric and imperial

Example: 70 kg and 1.75 m gives 70 / (1.75 x 1.75) = 22.9. See metric and imperial units if you need to convert first.

The standard categories

WHO adult BMI ranges

Under 18.5— Underweight18.5-24.9— Normal25-29.9— Overweight30+— Obese

Try it: BMI CalculatorEnter your height and weight for an instant BMI and category.Open tool

BMI is a screening tool, not a diagnosisBMI does not distinguish muscle from fat or account for age, sex, or body composition, so athletes can read as 'overweight'. Treat it as a rough population-level screen, and rely on a clinician for anything health-related.

Reading your result

The categories above apply to most adults, not children or pregnant people
A single number is not a health verdict — trends matter more
Waist measurement and body composition add context BMI misses
For children and teens, BMI is compared to age-and-sex percentiles instead