Ideal Weight Calculator

What this calculator does

This calculator estimates a reference body weight from height and sex using four widely cited clinical formulas — Devine, Robinson, Miller and Hamwi — and shows their average. Alongside them it gives the BMI-based healthy weight range, the band of weights that places body mass index between 18.5 and 24.9 for your height. You enter your height in centimetres or inches, pick your sex, and every figure updates immediately. All of the arithmetic happens inside your browser.

Why you might need it

“Ideal body weight” is a concept used in several practical settings. The Devine formula, for instance, originated in 1974 as a way to scale medication doses to body size, and the others followed as refinements. Outside clinical dosing, people look up an ideal-weight figure to get a height-based reference point, to compare it against the broader healthy-weight range, or simply to understand how these well-known formulas differ. Because there is no single agreed equation, seeing four results together is more informative than any one of them alone — the average smooths out their individual quirks, and the spread shows how much they disagree.

How to use it

1. Choose your sex. Each formula has separate coefficients for men and women.
2. Pick metric (centimetres) or imperial (inches) for height.
3. Enter your height.
4. Read the per-formula table — each result is shown in kilograms and pounds — the average row, and the BMI-based healthy weight range below it.
5. Use the copy button to save the average, or Reset to restore the defaults.

How it’s calculated

Every formula is expressed in the same shape: a base weight at a height of 5 feet, plus a fixed amount for each inch above that. The calculator first converts height to inches if needed, then computes inches above 5 ft. With that value:

• Devine: men 50 + 2.3 × inches kg; women 45.5 + 2.3 × inches kg.
• Robinson: men 52 + 1.9 × inches; women 49 + 1.7 × inches.
• Miller: men 56.2 + 1.41 × inches; women 53.1 + 1.36 × inches.
• Hamwi: men 48 + 2.7 × inches; women 45.5 + 2.2 × inches.

The average is simply the mean of the four kilogram results, and pounds are obtained by dividing kilograms by 0.45359237. The BMI-based range uses the body mass index definition, weight = BMI × height², with height in metres: the lower bound multiplies 18.5 by height squared and the upper bound multiplies 24.9 by height squared. That produces a span of weights rather than a single number.

Common pitfalls

The most common misreading is treating any one formula’s output as a precise target. These equations are straight-line approximations fitted decades ago to particular populations; they take no account of frame size, muscle mass or body composition, so two people of the same height and sex can be healthy at quite different weights. Another pitfall is the reference height — because the formulas are anchored at 5 feet, very short heights produce extrapolated values that stray from the data the formulas were built on. Finally, the BMI-based range and the four formulas answer slightly different questions: one is a band defined purely by height, the other a set of point estimates that also depend on sex, so they will not line up exactly.

Tips and related calculations

Looking at the spread between the highest and lowest formula is often more useful than the average itself — a wide spread is a reminder of how much these models disagree. Comparing the formula results against the BMI healthy-weight band shows whether the point estimates fall inside the broader range for your height. Body mass index and body fat percentage are natural companion calculations, each describing body size from a different angle. Because every conversion and formula runs locally, you can change the height and watch all six figures update instantly, and nothing you enter ever leaves your browser.