BMI Calculator
Body mass index with category
What is BMI Calculator?
BMI Calculator is a free online calculator from Farvixo that lets you body mass index with category. It recalculates as you type and shows the working, so you can check how the answer was reached rather than trusting a single number. Everything is computed in your browser — your figures are never sent anywhere.
How to use BMI Calculator
Fill in the fields in BMI Calculator. Everything is calculated in your browser, so your figures are never sent anywhere.
BMI Calculator recalculates as you type, with the working shown so you can check how the answer was reached.
Copy the result or export it as a report. Free, unlimited, no sign-up.
Frequently Asked Questions
How is BMI calculated?
Weight in kilograms divided by height in metres squared. The WHO bands are under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, and 30 or above obese.
Is BMI a reliable measure of health?
It is a population screening tool, not a diagnosis. It cannot distinguish muscle from fat, so athletes register as overweight while someone sedentary with low muscle mass can register as normal. Treat it as one crude number among many.
Do the thresholds differ by ethnicity?
Yes. Several health authorities use lower thresholds for South Asian populations — often 23 for overweight and 27.5 for obese — because cardiometabolic risk rises at a lower BMI. Follow local clinical guidance.
Are my measurements stored?
No. The calculation runs in your browser and nothing is transmitted or saved.
Does it work for children?
No. Child and teenage BMI is assessed against age and sex percentile charts, not the adult bands, so an adult calculator gives a misleading answer. Use a paediatric chart or ask a doctor.
What you can use BMI Calculator for
- Checking a figure quoted to you before you commit to it
- Students following the method as well as the answer
- Planning a budget, loan or timeline with several scenarios side by side
- Anyone who wants a quick answer without a spreadsheet
BMI Calculator at a glance
- Tool
- BMI Calculator — Calculator Tools
- Purpose
- Body mass index with category
- Input
- Text or values you enter directly
- Output
- The calculated result, with the working shown
- Processing
- In your browser — files are never uploaded to a server
- Price
- Free, unlimited, no account required
- Limitations
- Bounded by your device's memory and CPU rather than a server quota
Tips for better results
- Keep units consistent throughout — mixing months and years is the most common source of a wrong answer.
- Try the calculation at a slightly worse input to see how sensitive the result is before relying on it.
- The working is shown for a reason: if a figure looks surprising, read the steps before assuming it is wrong.
Common problems and how to fix them
The result differs from another calculator
Check the compounding basis and rounding rule. Both tools can be right under different conventions.
The output is blank
A required field is empty or holds a non-numeric character — a currency symbol or thousands separator pasted along with the number.
The number seems far too large
Almost always a units mismatch, such as an annual rate entered where a monthly one was expected.
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