BMI Prime calculator
BMI Prime turns BMI into a simple ratio: 1.0 means you sit exactly on the upper edge of the healthy band.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter weight and height.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
BMI Prime = BMI ÷ 25, where BMI = weight (kg) ÷ height (m) squared.
Example
Inputs: Weight = 70 kg, Height = 175 cm. Result: BMI Prime: 0.91; BMI: 22.9; Difference from the 25 limit: -8.6%.
Limits and caveats
- It carries the same limits as BMI and does not measure fat directly.
- The 25 limit is the WHO adult cut-off; some Asian guidelines use lower limits.
Questions about this tool
What is a healthy BMI Prime?
From 0.74 to under 1.0, matching a BMI of 18.5 to under 25.
What does a BMI Prime of 1.2 mean?
Your BMI is 20% above the upper healthy limit, which is a BMI of 30, the start of obesity.
Why use it instead of plain BMI?
It shows the percentage gap to the healthy limit directly, with no extra arithmetic.