Health tool
BMI Calculator
The BMI Calculator works out your Body Mass Index from your weight in kilograms and height in centimeters, then places the result in a standard category.
The calculation runs locally in your browser, so your measurements never leave your device.
Privacy & data handling
Browser processingThis tool processes your input locally in your browser. Nothing is uploaded to a server or sent to an external service.
Interactive tool
BMI Calculator
Your BMI falls within the standard healthy weight range for adults (18.5 – 24.9).
Underweight
< 18.5
Healthy
18.5–24.9
Overweight
25–29.9
Obesity
≥ 30
Formula (Standard Quetelet Index):
BMI = weight(kg) ÷ height(m)²
= 70.0 ÷ (1.75)² = 22.9
Screening measure only: BMI is a population-level screening indicator of body mass relative to height. It does not directly measure body fat percentage or body composition.
BMI interpretation may not apply to:
- Children and adolescents — WHO/CDC age-and-sex growth percentiles are used instead of adult cutoffs.
- Pregnancy — weight gain is expected and normal BMI categories do not apply.
- Highly muscular athletes — high muscle mass can push BMI above standard cutoffs despite low body fat.
Always consult a qualified healthcare professional for clinical weight assessment and health guidance.
Overview
What does BMI Calculator do?
Enter your weight in kilograms and height in centimeters, separated by a space. The tool computes your BMI and labels it: underweight, healthy range, overweight, or obesity range.
It is a screening number — useful for a quick health check, not a diagnosis.
Under the hood
How does it work?
BMI is weight in kilograms divided by height in meters squared. The tool converts your centimeters to meters, applies the formula, and maps the result to the standard World Health Organization categories.
Key features
Features of BMI Calculator
Use cases
When should you use BMI Calculator?
Quick health screening
Get a baseline number to track over time or discuss with a professional.
Tracking changes
Recompute after weight changes to see which category you move through.
Understanding the metric
See how the BMI scale maps to underweight, healthy, and overweight ranges.
Step-by-step
How to use BMI Calculator
- Step 1
Enter your weight in kilograms and height in centimeters.
- Step 2
View your BMI and category instantly.
Real example
Example
Before (input)
70 175
After (result)
BMI: 22.9 (healthy range)
70 kg and 175 cm falls in the healthy range.
Technical information
How the details work
Input is parsed as two numbers: weight in kilograms and height in centimeters. BMI equals weight divided by (height in meters) squared, rounded to one decimal, and categorized using standard thresholds: under 18.5, 18.5–24.9, 25–29.9, and 30 and above.
Privacy & security
Your data stays yours
All calculations happen locally in your browser. Your measurements are never uploaded or stored.
Local processing — files stay in your browser
- The calculation runs on your device with no network requests.
- Nothing you enter is saved after the tab is closed.
- No account or data collection of any kind.
Limitations
What this tool does not do
- BMI does not distinguish muscle from fat — athletes can score high while healthy.
- It does not account for age, sex, or body composition.
- It is a screening tool, not a medical diagnosis.
Frequently asked questions
Common questions about BMI Calculator
What do the BMI categories mean?
Under 18.5 is underweight, 18.5–24.9 is healthy range, 25–29.9 is overweight, and 30+ is the obesity range.
Why does my BMI say overweight when I exercise a lot?
BMI only uses weight and height — it cannot tell muscle from fat. Highly muscular people can read as overweight despite low body fat.
Is BMI a diagnosis?
No — it is a quick screening number. A healthcare professional weighs it with other factors.
Is my data private?
Yes. Everything runs in your browser and nothing is transmitted or stored.
What units does it use?
Kilograms for weight and centimeters for height — enter them as two numbers separated by a space.
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