Broca Index Calculator
Calculate ideal body weight using the historical Broca formula and modern Brugsch modifications. Compare 19th-century anthropometry with current health standards.
About
Medical professionals and anthropologists historically relied on the Broca index to estimate ideal body weight before Body Mass Index became the standard. Paul Broca developed this method in 1871 for quick usage in clinical settings where complex calculation was impractical. The formula assumes a linear relationship between height and weight that simplifies patient assessment. Modern applications often utilize the Brugsch adaptation to correct for height extremes. This adjusted version applies different subtraction constants based on specific height tiers. Reliability decreases significantly for very tall or very short individuals due to the scaling limitations of linear equations. Users frequently consult this metric to understand historical weight expectations versus modern obesity guidelines.
Formulas
The standard Broca calculation uses a simple subtraction logic. The Brugsch variant introduces conditional branching based on height H in centimeters.
For the original Broca method applied to women generally involves a further reduction.
Reference Data
| Height Range (cm) | Original Broca Formula | Brugsch Modification | Result Difference (180cm) |
|---|---|---|---|
| < 165 | H − 100 | H − 100 | 0 kg |
| 165 to 175 | H − 100 | H − 105 | −5 kg |
| > 175 | H − 100 | H − 110 | −10 kg |
| General | H − 100 | Variable Constants | Varies |
| Women | H − 100 − 15% | N/A | Lower |
| Metric Units | kg | kg | None |
| Accuracy | Low for Tall | Moderate | Improvement |
| Origin Year | 1871 | 1960s | Era Shift |