Body Mass Index Calculator – Calculate Your BMI Online
US Units
Result: kg/m2
Status: ?
Metric Units
Result: kg/m2
Status: ?
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Quick answer
Enter your height and weight (in metric or imperial units); the tool calculates your BMI using the standard formula and shows whether it falls in the underweight, normal, overweight, or obese range.
Key facts
- Uses the standard BMI formula: weight (kg) / height (m) squared|Supports both metric (cm, kg) and imperial (inches, lb) input units, converting internally to metric before calculating|Displays a standard weight-category label (e.g. underweight, normal, overweight) based on the result|Runs entirely in your browser via JavaScript, no data sent to a server|Free with no usage limit, informational only
What is this tool?
This tool calculates your Body Mass Index (BMI) from your height and weight, using either metric or imperial units, and shows the standard weight-category label associated with your result.How to use it
Select metric or imperial units, enter your height and weight, and your BMI value and weight-category label are calculated and displayed instantly.- Choose your preferred units (metric or imperial).|Enter your height.|Enter your weight.|View your calculated BMI value and its weight-category label instantly.
Example
Example: a height of 170 cm and weight of 65 kg gives a BMI of approximately 22.49, which falls in the "Normal" weight-category range.How it works
BMI = weight (kg) / height (m)^2. If you enter imperial units, the tool first converts: inches to meters by dividing by 39.3700787, and pounds to kilograms by dividing by 2.20462, before applying the same formula. This is the standard, internationally recognized BMI formula.Common use cases
Getting a quick general sense of whether your weight falls in a typical range for your height.|Tracking BMI changes over time alongside a fitness or health routine.|Understanding the standard BMI categories before a doctor's visit.|Comparing height/weight using either metric or imperial units without manual conversion.Benefits
Free, instant, supports both unit systems, and uses the same standard formula used in general health screening.Limitations
BMI is a general screening measure and does not account for muscle mass, bone density, body composition, age, sex, or ethnicity, so it can misclassify muscular or very lean individuals; it is not a diagnosis of health status. This tool provides an informational estimate only and is not medical advice -- consult a healthcare professional for a full health assessment.Privacy & your data
All calculations run locally in your browser using JavaScript. Your height and weight are not sent to or stored on the A2Z Tools server.Frequently asked questions
What is a healthy BMI?
For most adults a BMI between 18.5 and 24.9 is considered the healthy range. Below 18.5 is underweight, 25–29.9 is overweight and 30+ is classed as obese.
Does BMI account for muscle mass?
Is BMI accurate for athletes?
Not always. BMI cannot tell muscle from fat, so muscular people may read as "overweight" despite low body fat. Use it as a rough screen, not a verdict.
Is a high or low BMI a medical diagnosis?
Is my data stored when I use this calculator?
No. The calculation happens in your browser — the values you type never leave your device.
Can I use imperial units instead of metric?
Is my height and weight data stored anywhere?
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