Add the numbers for your scenario.
01Health & Fitness toolCalculated result
BMI Calculator
Body mass index and healthy weight range, metric or imperial.
100% FreeRuns instantlyNo watermark
- 1Enter detailsAdd the numbers for your scenario.
- 2CalculateVootkit updates the result instantly.
- 3ReviewCheck totals, notes and breakdowns.
Private by designProcessed on your device where possible.
Works on any deviceDesktop, tablet and mobile browsers.
No installationOpen the page and start working.
Always free coreUse the free plan for everyday tasks.
How to use BMI Calculator
Vootkit updates the result instantly.
02Check totals, notes and breakdowns.
03Copy the answer into your workflow.
04Your files stay private
Your work is processed locally in your browser where possible and is never added to a Vootkit upload library.
Learn more about privacyBMI is a population statistic being used as a personal one, which is where nearly all the confusion comes from. It is a quick screening number, and it is genuinely poor at distinguishing muscle from fat.
What BMI Calculator does
Calculates body mass index from weight and height, in metric or imperial units.
What it does not do is measure body composition. BMI is weight divided by height squared — it has no way of knowing whether the weight is muscle, fat, bone or fluid, which is why it misclassifies athletic and older bodies routinely.
The standard categories
| Under 18.5 | Underweight |
|---|---|
| 18.5 – 24.9 | Healthy range |
| 25 – 29.9 | Overweight |
| 30 and above | Obese |
| Formula | Weight in kg ÷ (height in metres)² |
| Units accepted | Metric (kg, cm) or Imperial (lb, in) |
| Known to misclassify | Muscular builds, older adults, and it varies by ancestry |
Detailed steps
- Choose metric or imperial.
- Enter weight and height.
- Read the result as a rough screening figure, not a diagnosis.
Worth knowing
A muscular person can register as overweight on BMI while carrying very little fat, and an older person who has lost muscle can sit in the healthy range while carrying too much. Waist measurement tracks health risk better than BMI for most individuals, which is why clinicians increasingly ask for both.
Frequently Asked Questions
Is BMI accurate for athletes?
Often not. Muscle is denser than fat, so a well-trained person can land in the overweight or obese band with low body fat. BMI was designed to describe populations, and it does that reasonably well; it was never designed to assess an individual.
Do the thresholds apply to everyone?
No. Some health bodies use lower thresholds for people of South Asian ancestry, because health risks appear at a lower BMI. The categories here are the standard international ones, which is not the same as the right ones for every individual.
Does BMI work for children?
Not with these categories. Children are assessed against age and sex percentile charts, because their bodies change proportion as they grow. A child’s BMI number means nothing without the chart.
What is a better measure?
For individuals, waist circumference or waist-to-height ratio tracks risk more closely, because it reflects where fat is carried rather than only how much you weigh. Discuss anything that concerns you with a clinician rather than a calculator.
Is BMI Calculator free?
Yes. The Vootkit free plan includes 5 tool runs a day. Upgrade to Vootkit Pro for unlimited daily use, an ad-free workspace and saved workflows.
Are my files uploaded?
No. BMI Calculator runs entirely in your browser — your file is processed on your own device and never sent to a server. There is nothing for us to store or delete.
Do I need to install anything?
No. BMI Calculator works in any modern browser on desktop, tablet or phone. Open the page and start.
How often can I use it? Is there a daily limit?
On the free plan you get 5 tool runs a day. When you reach the limit you'll see a prompt to upgrade, and it resets the next day. Vootkit Pro removes the cap entirely for unlimited daily use.
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This tool processes everything locally in your browser. You can disconnect from the internet after the page loads and it will still work.