What do the formulas estimate?
This calculator compares three historical adult ideal-body-weight formulas. Results can differ for the same person; that is expected and does not mean one formula is definitively correct.
Modified Broca
Female coefficients: (height in cm − 100) × 0.85
Devine
Female coefficients: 45.5 kg + 2.3 kg × each inch over 5 ft
Robinson
Female coefficients: 49 kg + 1.7 kg × each inch over 5 ft
Devine and Robinson are not calculated below 152.4 cm. This avoids mechanically extending the formulas below their original reference point.
Sources and interpretation limits
Devine, Robinson and Broca-family equations are historical ideal body weight (IBW) approaches. Medical literature notes that these formulas can produce different values for the same person and do not directly account for body composition, muscle and bone structure, genetics or individual health status.
Hesapica presents these equations as comparative adult estimates. The sex-adjusted Broca variant used here, like other IBW formulas, should not be treated as a personal health target, diagnosis, treatment recommendation or medication-dosing instruction.
- NCBI / PMC — Ideal body weight: a commentary
- NCBI / PMC — Universal equation for estimating ideal body weight and body weight at any BMI
Sources last checked: October 12, 2026. Results are historical formula estimates, not direct measurements.
Frequently Asked Questions
Is ideal weight a single exact number?
No. Historical ideal-body-weight formulas can produce different estimates. This calculator shows the available estimates and, when more than one formula applies, their range. It does not present them as a medical target.
Why does the calculator not ask for age?
Age is not a variable in the core Modified Broca, Devine or Robinson equations used here, so the tool does not ask for data that does not change these formula results.
What happens below 152.4 cm (5 ft)?
The Modified Broca estimate is still shown. Devine and Robinson start from a 5 ft reference point, so this calculator does not mechanically extrapolate those two formulas below 152.4 cm.
What does the formula midpoint mean?
It is the arithmetic mean of the available formula estimates. It is not a separate medical formula; it is only a central comparison value across the estimates.
Is this calculator medical advice?
No. The results are estimates from historical adult ideal-body-weight formulas and do not replace an assessment by a qualified health professional.