BMI Calculator
Body mass index with your WHO weight category and the healthy weight range for your height — metric or imperial.
Reviewed by the OmniCalc teamMethod verified 2026-07-01
22.9BMI
= Normal weight= healthy range for your height: 56.7–76.6 kg
BMI 22.9, Normal weightInformational only — not medical advice. BMI does not distinguish muscle from fat.
How to use the BMI calculator
- 1Choose Metric (kg · cm) or Imperial (lb · ft in) with the units control.
- 2Enter your weight and height — the BMI updates as you type.
- 3Read your WHO category and the healthy weight range for your height, shown alongside the number.
- 4Use the range as a target band, not a single “correct” weight.
The BMI formula
BMI = weight (kg) ÷ height² (m²)
Body mass index relates weight to height on a single scale. It was devised by Adolphe Quetelet in the 1830s and adopted by the WHO as a population-level screening measure. It is unit-blind once normalized — this calculator converts imperial inputs to metric before applying the formula, so both modes give identical results.
WHO BMI categories (adults)
| Category | BMI range |
|---|---|
| Underweight | < 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25 – 29.9 |
| Obese (class I) | 30 – 34.9 |
| Obese (class II) | 35 – 39.9 |
| Obese (class III) | ≥ 40 |
Read BMI as a screen, not a verdict
BMI weighs the scale against your height, but it can’t tell muscle from fat or where that weight sits. A muscular athlete can land in the “overweight” band while a sedentary person of the same BMI carries more fat. Pair it with a waist measurement and how you feel, and treat any concern as a conversation to have with a clinician — not a diagnosis from a number.
Frequently asked questions
How is BMI calculated?
BMI = weight in kilograms divided by height in meters squared (kg/m²). For example, 70 kg at 1.75 m gives 70 ÷ 1.75² = 22.9.
What is a healthy BMI?
The WHO defines the normal range for adults as a BMI of 18.5 to 24.9. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classed as obesity (in three classes).
Is BMI accurate for everyone?
No. BMI does not distinguish muscle from fat, so athletes can read as overweight, and it applies differently to children, pregnant women and the elderly. Treat it as a screening indicator, not a diagnosis.
Does this calculator work with pounds and feet?
Yes — switch the units control to Imperial and enter weight in pounds and height in feet and inches; the conversion to metric happens automatically.
Source: WHO expert consultation on BMI classification. This tool is informational and not a substitute for medical advice. Last reviewed 2026-07-01.