Broca and Lorentz ideal weight calculator
Broca is the quick rule many people know; Lorentz adds an adjustment for height and sex.
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How to use it
- Enter sex 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
Broca = height (cm) − 100. Lorentz for men = height − 100 − (height − 150) ÷ 4, for women = height − 100 − (height − 150) ÷ 2.
Example
Inputs: Sex = Male, Height = 175 cm. Result: Lorentz formula: 68.8 kg; Broca formula: 75 kg; Adjusted Broca (90%): 67.5 kg.
Limits and caveats
- These are old rules of thumb that ignore age and muscle.
- Plain Broca runs high for very tall people.
Questions about this tool
What is the Broca formula?
Subtract 100 from your height in cm, so 170 cm gives 70 kg.
What is adjusted Broca?
It takes 90% of the Broca result to correct its high values; some sources use 85% for women.
Why does Lorentz give women a lower weight?
It subtracts half of the height above 150 cm for women and only a quarter for men.