Devine Formula: The most widely used IBW formula, originally created for drug dosing. It tends to give middle-of-the-road estimates and is the default in many clinical settings.
Robinson Formula: Generally produces slightly lower estimates for men and slightly higher for women compared to Devine. Developed from population data in 1983.
Miller Formula: Tends to give the highest ideal weight among the four, especially at taller heights. It uses a smaller per-inch increment, making it less sensitive to height changes.
Hamwi Formula: The oldest of the four (1964), with the steepest per-inch increment for men. It tends to give higher estimates for tall men and lower estimates for shorter individuals.
Why four formulas? No single formula is "right." Viewing all four together gives you a reasonable range rather than a false sense of precision. If three or four agree within a few pounds, that range is a useful reference.
How This Calculator Works
You enter your height (feet and inches or centimeters) and sex. The tool applies four classic ideal body weight formulas — Devine, Robinson, Miller, and Hamwi — each of which starts from a base weight at 5 feet and adds a fixed amount per inch of height above that, with separate constants for men and women. Results are shown in your chosen unit. The formulas do not account for frame size, age, muscle mass, or body composition.
Quick Questions
Which formula should I trust most?
Devine is the most commonly used in clinical practice, particularly for drug dosing. But for setting a personal weight target, looking at the range across all four formulas gives a more realistic picture than picking any single one.
Why are the results different from a BMI-based ideal weight?
BMI-based ideal weight works backward from a target BMI (usually 21.7–23), while these formulas use fixed per-inch increments. The two approaches were derived from different populations, so they rarely agree exactly but generally overlap.
Do these formulas work for very short or very tall people?
These formulas were developed from data on adults of roughly average height (5'0"–6'2"). At extreme heights, they become less reliable. For people under 5 feet, the formulas may not apply — consult a clinician instead.
Should I use ideal weight for medication dosing?
Some medications (like aminoglycosides and certain anesthetics) use adjusted body weight rather than actual or ideal weight. Always follow your prescriber's guidance — this calculator is for reference only, not clinical dosing.