About BMI
BMI is a screening tool that uses height and weight.
Learn how BMI is calculatedBMI Calculator
Body Mass Index
Enter your values, then calculate to see a verified result.
Reference range
How this result is calculated
A clear calculation path based on your inputs.
Inputs usedReview the information used for this result.
Full calculation and sourcesReview the equation, normalized inputs, assumptions, and version.
Versioned calculationFormula v1.0.0
Adult BMI ranges
- Below 18.5
- Underweight
- 18.5 - 24.9
- Healthy range
- 25.0 - 29.9
- Overweight
- 30.0 and above
- Obese
Important limitation
BMI does not measure body fat directly.
View limitationsConvert to metersHeight in cm ÷ 100
170 cm = 1.70 mSquare your heightHeight (m) × height (m)
1.70 × 1.70 = 2.89Divide weight by height²Weight ÷ height²
70 ÷ 2.89 = 24.2Interpretation
Your result of is classified as for adults.
BMI is a screening measure and should be considered with other health information.
Small, sustainable changes can improve overall health.
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Related calculators and resources
Method and test recordFormula v1.0.0
- Recorded scope
- health
- Publisher
- CalculatorGeek
- Recorded review date
- 2026-08-30
- Next source review
- 2027-08-30
- Definition fixtures
- 4 configured scenarios
- Published examples
- 4 shown below
Recorded method
No tool-specific review method has been recorded.
These records describe the published model and reference tests. A test-case count is not a certification of every possible input or an independent specialist review. Editorial policy
Known limitations
- BMI is a screening measure and does not directly measure body fat.
- Adult reference ranges may not apply to children, pregnancy, or some athletic populations.
Method sources
Latest model update
2026-08-30 - Initial versioned schema and generic renderer package.
Reference inputs and expected results
Up to 12 examples from the configured definition fixtures are shown. Expected values use the stated output units; invalid inputs are intended to be rejected.
| Case | Inputs | Expected result |
|---|---|---|
| metric healthy adult | Height: 170 cm; Weight: 70 kg | BMI: 24.2; Healthy weight minimum: 53.5 kg; Healthy weight maximum: 72 kg; classification: healthy |
| imperial equivalence | Height: 66.9291339 in; Weight: 154.323584 lb | BMI: 24.2; classification: healthy |
| underweight boundary | Height: 2 m; Weight: 73.96 kg | BMI: 18.5; classification: underweight (allowed numeric tolerance: 0.1) |
| invalid height | Height: 20 cm; Weight: 70 kg | Reject invalid input: height |
Report an issue with this tool. Include the page URL, units, expected answer, and steps to reproduce. Do not include sensitive personal information.
On this page
What is BMI?
BMI is weight in kilograms divided by height in meters squared. It is an adult weight-status screening measure, not a direct body-fat measurement or a diagnosis. Age and sex do not change this formula.
How BMI is calculated
BMI divides weight in kilograms by height in meters squared. Imperial measurements are converted before the same formula is applied.
BMI = weight (kg) ÷ height² (m)
Understanding your result
Use the unrounded BMI for category boundaries; a rounded display can sit on the other side of a cutoff. Muscle mass, pregnancy, and some medical conditions can affect interpretation. Children and teens need age- and sex-specific growth references rather than this adult classification.
For a different body-composition estimate, see the Body Fat Calculator. Military screening is a separate policy-specific task; use the Navy Body Fat Calculator only when that standard applies.
Inputs, outputs and result meaning
Calculates bMI, healthy weight minimum, and healthy weight maximum from height, weight, age (optional), and sex (optional) with visible method, validation, precision, and limitations.
Inputs
- Height
- Supported units include centimeters (cm), meters (m), inches (in), feet (ft), and feet / inches (ft / in). The supported range is 0.5 through 2.8.
- Weight
- Supported units include grams (g), kilograms (kg), and pounds (lb). The supported range is 10 through 700.
- Age (optional)
- Age is optional and does not change the standard adult BMI formula. Supported units include years (yr). The supported range is 18 through 120. This field is optional.
- Sex (optional)
- Sex is optional and does not change the standard adult BMI formula. Available choices are Female, Male, and Prefer not to say. This field is optional.
Outputs
- BMI
- This is the primary result. The visible value uses up to 1 decimal places according to the output rule.
- Healthy weight minimum
- It is displayed in kg. The visible value uses up to 1 decimal places according to the output rule.
- Healthy weight maximum
- It is displayed in kg. The visible value uses up to 1 decimal places according to the output rule.
BMI = weight (kg) ÷ height² (m). Keep the result label, unit, selected mode, and stated limitations together when sharing the answer.
Frequently asked questions
What does the BMI Calculator calculate?
BMI is a screening tool that uses height and weight.
Which inputs does the BMI Calculator use?
The calculation uses Height, Weight, Age (optional), Sex (optional). Use the units and ranges shown beside each field.
How should I interpret the result?
Read the primary value together with its classification, calculation steps, units, assumptions, and limitations. Do not use a rounded display value as if it were more precise than the source inputs.
What are the main limitations of the BMI Calculator?
BMI is a screening measure and does not directly measure body fat. Adult reference ranges may not apply to children, pregnancy, or some athletic populations.
What the BMI Calculator answers
The BMI Calculator calculates bMI, Healthy weight minimum, and Healthy weight maximum from height, Weight, Age (optional), and Sex (optional). Read the primary answer together with its unit, supporting outputs, and interpretation rather than treating the number as context-free.
Method, assumptions and precision
BMI = weight (kg) ÷ height² (m).
The engine retains working precision through the calculation and rounds only the visible result according to the output definition. Unsupported values or denominators should produce a validation message rather than an infinite or undefined display.
Reference example
metric healthy adult: Height: 170 cm; Weight: 70 kg. The expected result is BMI: 24.2; Healthy weight minimum: 53.5 kg; Healthy weight maximum: 72 kg; classification: healthy.
Interpretation checks
- BMI is a screening measure and does not directly measure body fat.
- Adult reference ranges may not apply to children, pregnancy, or some athletic populations.
- Keep the displayed unit and input convention with the result.
- Use an unrounded value when the result feeds another calculation.