How to use the Ideal Weight
- Enter your height and select your sex.
- Compare the four formula results with the healthy BMI range.
- Treat the range, not any single figure, as the target.
- Adjust upward if you carry substantial muscle mass.
How the calculation works
The clinical formulas share a structure: a base weight at five feet plus a fixed increment per additional inch. Devine, developed in 1974 for drug dosing rather than health targets, gives 50 kg plus 2.3 kg per inch for men and 45.5 kg plus 2.3 for women; Robinson, Miller and Hamwi adjust the constants. None was designed as a body-composition goal, which is why they diverge by several kilograms at the same height.
A healthy BMI band of 18.5 to 24.9 usually produces a wider and more realistic range, and for most people that band is the better reference. All of these methods share the same blind spot: they use only height and sex, ignoring frame size, muscle mass and age. A muscular athlete will exceed every one of them while carrying low body fat, which is why body composition should override the number whenever the two disagree.
Devine men: 50 + 2.3 × (inches over 60) kg ; women: 45.5 + 2.3 × (inches over 60) ; healthy BMI range: 18.5–24.9 × height(m)²Source: Devine (1974), Robinson (1983), Miller (1983) and Hamwi (1964) ideal body weight formulas; WHO BMI classification.
Worked example
A woman 5 ft 6 in tall (1.676 m, 6 inches over 60).
- Devine: 45.5 + 2.3 × 6 = 59.3 kg.
- Robinson: 49 + 1.7 × 6 = 59.2 kg.
- Hamwi: 45.5 + 2.27 × 6 = 59.1 kg.
- Healthy BMI range: 18.5 × 2.809 = 52.0 kg to 24.9 × 2.809 = 69.9 kg.
The formulas cluster near 59 kg, but the healthy range spans 52 to 70 kg — plenty of room for differing builds and muscle mass.
Frequently asked questions
Which formula is most accurate?+
None is authoritative for health — they were built for clinical dosing. The healthy BMI range is a more realistic target, and body composition matters more than either.
Why do the formulas disagree?+
Each was derived from different populations with different base constants and increments. The spread of a few kilograms is a reminder that a single ideal weight does not exist.
Should muscular people use these?+
Not as a target. Muscle is denser than fat, so athletes routinely exceed every formula while being lean and healthy. Use body fat percentage instead.
Does ideal weight change with age?+
The formulas do not account for age, though body composition shifts over time. Slightly higher weight in older adults is associated with better outcomes, so a rigid target becomes less useful with age.
Last reviewed August 31, 2026. We review this page whenever the underlying formula, tax year, published rate or standard changes.