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BMI Calculator
Free · No sign-up · Works in your browser
BMI Categories
| BMI Range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obese |
About BMI Calculator
Body Mass Index (BMI) is a simple calculation using a person's height and weight. The formula is BMI = kg/m² where kg is a person's weight in kilograms and m² is their height in metres squared.
A BMI of 25.0 or more is overweight, while the healthy range is 18.5 to 24.9. BMI applies to most adults 18-65 years.
Quick answer
BMI Calculator is a free browser tool from SimpleCounter. Free BMI calculator online. Calculate your Body Mass Index instantly with metric or imperial units. Find out if you're underweight, normal, overweight or obese. Enter your values and the result updates as you type — there is nothing to install and no account to create.
- Definition: BMI Calculator
- A BMI calculator takes the numbers you enter and returns the result using the standard formula for that calculation, so you do not have to work it out by hand.
Key facts
| Cost | Free, with no account and no usage limit. |
|---|---|
| Where the maths happens | In your browser. The values you type are not sent to a server. |
| Devices | Any modern browser on phone, tablet, laptop or desktop. |
| Accuracy | Standard published formulas, shown with the units you selected. |
| Intended use | Estimates for everyday and educational use, not professional advice. |
How to use the BMI calculator
- Type your value into the first field.
- Choose the unit or option that matches your figures, if the tool offers a choice.
- Read the result — it recalculates immediately, with no submit button.
- Change any input to compare a second scenario side by side.
How this page relates to the rest of the site
- Type of
- Free online tool
- Related tools
- Online counter, Online stopwatch
- Explained in
- Guides and how-tos
- Published by
- SimpleCounter
Disclaimer: This tool is provided for educational and informational purposes only. Results are estimates based on standard formulas and the inputs you provide. For financial, medical, legal, or tax decisions, consult a qualified professional. See our full disclaimer.
Frequently Asked Questions
What is BMI?
Body Mass Index (BMI) is a measure of body fat based on height and weight. It's calculated by dividing weight in kilograms by height in meters squared.
What is a healthy BMI?
A BMI between 18.5 and 24.9 is considered normal/healthy weight. Below 18.5 is underweight, 25-29.9 is overweight, and 30+ is obese.
Is BMI accurate?
BMI is a useful screening tool but doesn't directly measure body fat. Athletes with high muscle mass may have a high BMI despite being healthy.
How is BMI calculated?
BMI = weight(kg) / height(m)². For imperial: BMI = (weight(lbs) / height(in)²) × 703.
Benefits of using the BMI Calculator
What you actually get compared with a mechanical clicker, a notes app, or trying to hold the number in your head.
Your count survives real life
Totals are saved on your device as you go, so a locked screen, a closed tab, or a lost signal does not reset anything.
Works offline once loaded
Install it to your home screen and it keeps working in a warehouse, a pool hall, a field, or a plane — no connection needed.
Private by default
Counts stay in your browser. There is no cloud sync, no profile, and nothing about what you count is sent to us.
Free, with no sign-up
Works offline once loaded
Counts stay on your device
Installable as an app
Runs in your browser — nothing to download
72+ counter types available
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