BMI Calculator
Check your Body Mass Index in seconds — free, no account required, and nothing leaves your device. Switch between metric (cm / kg) and imperial (ft / in / lbs) and get your BMI score along with your WHO category and a colour-coded gauge instantly.
BMI categories (WHO standard)
Underweight
< 18.5
Normal weight
18.5 – 24.9
Overweight
25 – 29.9
Obese
≥ 30
BMI is a screening tool, not a diagnostic measure. It does not account for muscle mass, bone density, or fat distribution. Consult a healthcare professional for personal medical advice.
How It Works
Pick your units
Tap Metric for centimetres and kilograms, or Imperial for feet, inches, and pounds. The fields switch instantly — no page reload.
Enter height & weight
Type your height and weight into the fields. Your BMI appears the moment you finish typing — no button to press.
Read your result
See your BMI score, your WHO category (Underweight, Normal, Overweight, or Obese), and where you sit on the colour-coded gauge at a glance.
Why users love this tool
- ✓ Your data never leaves your device — the calculation runs entirely in your browser, not on our servers, so your height and weight are never stored or shared.
- ✓ Results in seconds — there's no upload or download time because nothing leaves your device.
- ✓ No account needed — just open the page and start using it straight away.
BMI Scale — WHO Adult Categories
The World Health Organization defines four BMI categories for adults aged 18 and over:
| BMI Range | Category | What it means |
|---|---|---|
| < 18.5 | Underweight | May indicate nutritional deficiency; consider speaking to a doctor. |
| 18.5 – 24.9 | Normal weight | The healthy range for most adults according to the WHO. |
| 25 – 29.9 | Overweight | Slightly above healthy range; lifestyle changes are often recommended. |
| ≥ 30 | Obese | Associated with higher health risks; a healthcare professional can help. |
BMI Examples
| Height | Weight | BMI | Category |
|---|---|---|---|
| 165 cm (5′5″) | 50 kg (110 lbs) | 18.4 | Underweight |
| 170 cm (5′7″) | 65 kg (143 lbs) | 22.5 | Normal weight |
| 175 cm (5′9″) | 82 kg (181 lbs) | 26.8 | Overweight |
| 180 cm (5′11″) | 100 kg (220 lbs) | 30.9 | Obese |
Limitations of BMI
BMI is a widely used screening tool, but it has well-known limitations:
- Does not measure body fat directly — a muscular athlete can have a high BMI without excess fat.
- Does not account for fat distribution — where fat is stored (e.g. around the waist) matters for health risk.
- Age and sex differences — older adults tend to have more body fat at the same BMI than younger adults.
- Ethnicity — some health organisations use lower BMI thresholds for certain ethnic groups.
Features
- Metric & imperial: switch between cm/kg and ft/in/lbs with one tap.
- Instant results: BMI and category update as you type — no button press needed.
- Visual gauge: colour-coded bar shows exactly where your BMI falls on the scale.
- WHO categories: Underweight, Normal weight, Overweight, and Obese at a glance.
- Fully private: nothing is uploaded or stored — the entire calculation runs in your browser.