Health · Free online calculator
BMI Calculator
Calculate body mass index as a general screening measure for adults.
CALCULATOR GUIDE
How the BMI Calculator works
Calculate body mass index as a general screening measure for adults. This guide explains the inputs, calculation method, example and key limitations so you can check whether the result fits your question.
Calculate body mass index as a general screening measure for adults.
BMI = weight in kilograms ÷ height in metres squared.
Inputs to prepare
Before you calculate, gather the values the question asks for and check their units. Choose options carefully and use consistent dates, periods and starting values. The notes below describe the fields shown in the calculator above.
- Weight (kg)Use a numeric value and keep the displayed unit consistent. Allowed range: 0.1 to 1000
- Height (cm)Use a numeric value and keep the displayed unit consistent. Allowed range: 20 to 300
How to use the BMI Calculator
- Enter the details. Fill in each required field and use the units or formats shown next to it.
- Check your assumptions. Confirm dates, comparison values, time periods and selected options before submitting.
- Calculate and review. Read the result together with its unit, time period and any additional breakdown.
- Compare scenarios. Change one input at a time if you want to understand how different values affect the outcome.
Formula and worked example
BMI = weight in kilograms ÷ height in metres squared.
Example calculation
Use measured height and weight in the units requested.
Try the same values in the calculator above. If your result differs, recheck the units, input order, assumptions and rounding displayed by the tool.
What your result means
Calculate body mass index as a general screening measure for adults. Read the result label and unit carefully. A useful estimate describes only the inputs and assumptions supplied; it should not be treated as proof of a future outcome or a guarantee.
- Check the displayed unit and period before comparing results.
- Use values from a reliable source and keep them up to date.
- Repeat the calculation with an independent check when the outcome matters.
Assumptions and limitations
BMI is not a diagnosis and has different interpretations for children, teens, pregnancy and some athletes.
The calculator is a general-purpose tool. Actual outcomes may depend on local rules, provider terms, measurement standards or personal circumstances not represented in the fields. For consequential financial, health, legal, tax or construction decisions, confirm the result with an appropriate authoritative or qualified source.
Frequently asked questions
How does the bmi calculator work?
BMI = weight in kilograms ÷ height in metres squared.
Can I rely on the result as an exact answer?
BMI is not a diagnosis and has different interpretations for children, teens, pregnancy and some athletes.
How can I get a more useful estimate?
Use accurate inputs, keep units consistent, check the assumptions on this page and compare the output with an authoritative source when the result affects a financial, health, construction or legal decision.
For transparency, use the formula and worked example to check the output. Add authoritative references and have the calculation reviewed before relying on it for a consequential decision.