Is there such a thing as an ideal weight?

Not as a single number. Health outcomes across large populations relate to weight as a broad band, not a point, and the band is wide. That is why this page leads with the BMI range and treats the four equations as historical reference.

Why do these equations come from pharmacy?

Because drug doses often need to be scaled to lean mass rather than total mass, and clinicians needed a quick estimate from height alone. Devine's original appeared in a paper about gentamicin dosing. The fitness industry adopted them later, for a purpose they were never validated for.

Which equation should I use?

For a health target, none of them — use the healthy BMI range. If you need one for a dosing calculation, use whichever your local protocol specifies, because consistency matters more than the choice.

Why do the equations disagree by several kilograms?

They were fitted to different data with different goals, and they differ mainly in slope. At 5 ft 4 in they sit within about 3 kg of each other; at 6 ft 4 in the spread widens to nearly 10 kg, because a steeper per-inch increment compounds with height.

What about people under five feet?

All four are anchored at five feet and were not validated below it. Applied to shorter heights they extrapolate downward, and the page flags that. The BMI range remains meaningful at any height.

Ideal weight calculator

The four equations below all come from clinical pharmacy, where they normalise drug doses. None was designed to tell anyone what to weigh, so the healthy BMI range is shown first.

Result

These are estimates from population-level equations, not a measurement of you and not medical advice. Individual results vary widely. Talk to a doctor or a registered dietitian before making significant changes to how you eat or train.

How this is calculated

Devinedefault

              men:   50.0 kg + 2.3 kg per inch over 5 ft
women: 45.5 kg + 2.3 kg per inch over 5 ft

Source: Devine BJ., "Gentamicin therapy", Drug Intelligence and Clinical Pharmacy 8, 1974, pp. 650–655.
Assumes: A fixed increment of mass per inch of height above five feet, identical for everyone of the same sex.
Accuracy: The most widely used of the four, and the one most drug dosing protocols are built on. As a health target it has no validation behind it at all — it was never studied for that purpose.

Robinson

              men:   52.0 kg + 1.9 kg per inch over 5 ft
women: 49.0 kg + 1.7 kg per inch over 5 ft

Source: Robinson JD et al., American Journal of Hospital Pharmacy 40(6), 1983, pp. 1016–1019.
Assumes: The same shape as Devine, refitted.
Accuracy: A refinement of Devine intended to improve dosing accuracy. Reads slightly lower at tall heights and slightly higher at short ones.

Miller

              men:   56.2 kg + 1.41 kg per inch over 5 ft
women: 53.1 kg + 1.36 kg per inch over 5 ft

Source: Miller DR et al., American Journal of Hospital Pharmacy 40(9), 1983, p. 1622.
Assumes: The same shape, with the flattest slope of the four.
Accuracy: The least sensitive to height, so it converges with the others near 5 ft 8 in and diverges most at the extremes.

Hamwi

              men:   48.0 kg + 2.7 kg per inch over 5 ft
women: 45.5 kg + 2.2 kg per inch over 5 ft

Source: Hamwi GJ., "Therapy: changing dietary concepts", American Diabetes Association, New York, 1964, pp. 73–78.
Assumes: The same shape, with the steepest slope of the four.
Accuracy: The oldest of the four, developed for diabetes dietary planning. Its steeper slope means it reads highest of all four for tall people.

Which formula should you use

This page defaults to Devine. The most widely used of the four, and the one most drug dosing protocols are built on. As a health target it has no validation behind it at all — it was never studied for that purpose.

Robinson — A refinement of Devine intended to improve dosing accuracy. Reads slightly lower at tall heights and slightly higher at short ones.
Miller — The least sensitive to height, so it converges with the others near 5 ft 8 in and diverges most at the extremes.
Hamwi — The oldest of the four, developed for diabetes dietary planning. Its steeper slope means it reads highest of all four for tall people.

Ideal weight equations compared, men

The four clinical equations give a single number per height with no range. The final column is the healthy BMI range, which is the better answer to the question most people are asking.

Ideal weight equations compared, men
Height	Devine	Robinson	Miller	Hamwi	BMI 18.5–25
155 cm	52.4 kg	53.9 kg	57.6 kg	50.8 kg	44–60 kg
160 cm	56.9 kg	57.7 kg	60.4 kg	56.1 kg	47–64 kg
165 cm	61.4 kg	61.4 kg	63.2 kg	61.4 kg	50–68 kg
170 cm	65.9 kg	65.2 kg	66 kg	66.7 kg	53–72 kg
175 cm	70.5 kg	68.9 kg	68.7 kg	72 kg	57–77 kg
180 cm	75 kg	72.6 kg	71.5 kg	77.3 kg	60–81 kg
185 cm	79.5 kg	76.4 kg	74.3 kg	82.7 kg	63–86 kg
190 cm	84 kg	80.1 kg	77.1 kg	88 kg	67–90 kg

Questions

Is there such a thing as an ideal weight?: Not as a single number. Health outcomes across large populations relate to weight as a broad band, not a point, and the band is wide. That is why this page leads with the BMI range and treats the four equations as historical reference.
Why do these equations come from pharmacy?: Because drug doses often need to be scaled to lean mass rather than total mass, and clinicians needed a quick estimate from height alone. Devine's original appeared in a paper about gentamicin dosing. The fitness industry adopted them later, for a purpose they were never validated for.
Which equation should I use?: For a health target, none of them — use the healthy BMI range. If you need one for a dosing calculation, use whichever your local protocol specifies, because consistency matters more than the choice.
Why do the equations disagree by several kilograms?: They were fitted to different data with different goals, and they differ mainly in slope. At 5 ft 4 in they sit within about 3 kg of each other; at 6 ft 4 in the spread widens to nearly 10 kg, because a steeper per-inch increment compounds with height.
What about people under five feet?: All four are anchored at five feet and were not validated below it. Applied to shorter heights they extrapolate downward, and the page flags that. The BMI range remains meaningful at any height.

Calculators

Guides

Last reviewed August 20, 2026. Category: Weight reference.