Ideal Weight Calculator · Practical guide
Devine vs Robinson vs Miller Formulas
Same structure, different constants — the three equations, side-by-side results, and which one to trust.
At a glance
Three Formulas, One Structure
Devine, Robinson, and Miller all estimate ideal weight as a base plus a per-inch amount over 5 feet — they just use different constants. Devine (1974) was built for drug dosing, while Robinson and Miller (1983) refit the idea to newer population data.
Interactive tool
Ideal Weight Calculator
Enter your own values, then compare the result with the examples below.
The Equations
| Formula | Men | Women |
|---|---|---|
| Devine | 50 kg + 2.3 kg/in over 5 ft | 45.5 kg + 2.3 kg/in |
| Robinson | 52 kg + 1.9 kg/in | 49 kg + 1.7 kg/in |
| Miller | 56.2 kg + 1.41 kg/in | 53.1 kg + 1.36 kg/in |
Side-by-Side Results
For a 5'5" woman and a 6'0" man:
| Formula | 5'5" Woman | 6'0" Man |
|---|---|---|
| Devine | 125.7 lbs | 171.1 lbs |
| Robinson | 126.8 lbs | 164.9 lbs |
| Miller | 132.1 lbs | 161.2 lbs |
The three agree within a few pounds for women but spread wider for tall men — Devine runs about 10 lbs heavier than Miller at 6 feet.
Which One Should You Use?
Devine remains the clinical standard for dosing; Robinson and Miller may fit modern populations better. Because no formula sees your build, the calculator above shows all three plus the BMI 18.5-24.9 range, and applies your frame-size adjustment to each. Where they cluster is a reasonable middle; where they spread is a reminder that ideal weight is a zone, not a number.
Frequently Asked Questions
Why do the formulas give different answers?
Each was fit to different datasets and purposes. Devine optimized for clinical dosing; Robinson and Miller re-estimated the constants from later population surveys.
Which formula do doctors use?
Devine is still common for medication dosing. For general health screening, most clinicians now rely on BMI ranges and waist measurements.
Do the formulas work under 5 feet tall?
They subtract the per-inch amount below 5 feet, but accuracy drops at extremes of height — the BMI range is safer there.
Are these results in kilograms?
Yes, all three output kilograms. Multiply by 2.2046 to convert to pounds, or read both units in the results above.