Most BMI calculators in metric units ask for kilograms and centimetres, then bury the result in a chart that tells you nothing useful. The ones that do give context are behind paywalls or require account signups.
The free metric BMI calculator at Ultimate Tools takes kg and cm, returns your BMI instantly, and shows exactly where you fall on the standard WHO classification — no conversion, no signup, nothing stored.
What Is BMI and How Is It Calculated in Metric?
BMI (Body Mass Index) measures body fat based on height and weight. The metric formula is straightforward:
BMI = weight (kg) ÷ height (m)²
Example: 70 kg, 1.75 m → BMI = 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 = 22.9
The metric formula is simpler than imperial because it works directly with kilograms and metres — no conversion factors needed.
WHO BMI Classification (Metric)
| BMI Range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obese |
These are the standard WHO thresholds used globally. Some health organisations use slightly different ranges for specific populations — but for general reference, this table applies universally.
How to Use the Metric BMI Calculator
- Go to the BMI calculator with metric and imperial support
- Select Metric mode (kg / cm)
- Enter your weight in kilograms and height in centimetres
- Your BMI appears instantly with the WHO classification
No account, no data stored, calculation runs entirely in your browser.
Metric vs Imperial — Which to Use?
Use metric if:
- You measure weight in kilograms and height in centimetres (most of the world)
- You want to avoid conversion errors (converting pounds to kg introduces rounding)
- You're tracking BMI alongside other metric health data
Use imperial if:
- You only know your height in feet and inches and weight in pounds
- You're in the US and all your other measurements are imperial
The calculator supports both modes — switch without re-entering your data.
The metric BMI formula is weight in kg divided by height in metres squared — no conversion factors, no rounding errors.
What BMI Does and Does Not Measure
BMI is a population-level screening tool, not a diagnostic measurement. It does not account for:
- Muscle mass — athletes often have a high BMI despite low body fat
- Age — the same BMI carries different risk at 25 vs 65
- Distribution of body fat — where fat is stored matters more than total BMI for cardiovascular risk
- Bone density — higher than average bone density raises BMI without raising health risk
Use BMI as one data point, not a verdict. A result in the overweight range is worth discussing with a doctor — it is not a diagnosis.
Related: Imperial BMI Calculator
If you need to calculate BMI from pounds and feet/inches instead, the same tool handles imperial units. Switch to Imperial mode — enter weight in pounds and height in feet and inches — and the result converts automatically. No need to convert manually first.
Calculate your BMI in metric units now: free BMI calculator — metric kg and cm, no signup
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