Ideal Weight Calculator

Enter your height and gender to see your ideal body weight from three trusted formulas, plus your healthy weight range. Metric or imperial — everything stays on your device.

How ideal weight is calculated

Ideal-weight formulas estimate a target body weight from your height and gender only. The three best-known were designed in the 1960s–70s (originally to help doctors dose medication):

• Devine: men 50 kg + 2.3 kg per inch over 5 ft; women 45.5 kg + 2.3 kg per inch over 5 ft.
• Robinson: men 52 kg + 1.9 kg per inch over 5 ft; women 49 kg + 1.7 kg per inch over 5 ft.
• Hamwi: men 48 kg + 2.7 kg per inch over 5 ft; women 45.5 kg + 2.2 kg per inch over 5 ft.

Because they disagree slightly, the smartest approach is to treat them as a range, not one magic number — which is exactly what the calculator shows, alongside your BMI-based healthy range.

Ideal weight vs healthy weight range

A single "ideal" figure ignores that healthy bodies come in a band, not a point. The healthy weight range here is the span that gives a BMI of 18.5–24.9 for your height — for most people a spread of 15–20 kg. Where you sit in that band depends on muscle, frame size and body composition. Athletes with high muscle mass may sensibly weigh above their "ideal" figure while being very healthy.

Where these formulas came from — and their limits

It is worth knowing what these numbers were actually built for. The Devine formula was published in 1974 not as a health target but to help clinicians dose medication, where body size affects how a drug distributes. Robinson (1983) and Miller (1983) were later attempts to fit population data more closely, and Hamwi (1964) came from diabetes practice.

None was designed to tell an individual what to weigh, and all share the same blind spots. They use height and sex only — no account of frame size, muscle mass, age or body composition. They were derived largely from Western populations, so they fit others less well. And they behave oddly at the extremes, giving implausible figures for very short or very tall people. Treat the output as a reference point, not a goal.

Frame size changes the answer

Two people of identical height can carry healthily different weights because their skeletons differ. A rough check is the wrist test: wrap your thumb and middle finger around the opposite wrist. If they overlap you are likely small-framed; if they just touch, medium; if they do not meet, large-framed.

As a rule of thumb, subtract about 10% for a small frame and add about 10% for a large one. So a formula result of 70 kg reasonably spans about 63–77 kg depending on build. This is one reason the healthy range from BMI is often more useful than any single ideal figure.

Why athletes should ignore this number

Muscle is roughly 18% denser than fat, so anyone carrying significant muscle will exceed their "ideal" weight while being lean and healthy. A rugby player or regular lifter can sit 10–15 kg above the formula and have lower body fat than someone sitting exactly on it.

If that describes you, better measures are body fat percentage, waist circumference (under half your height is a good target), how clothes fit over time, and performance in training. The scale is the least informative of the four. Older adults should also note that a slightly higher weight is associated with better outcomes after about 65 — being underweight carries real risk at that age.

Frequently asked questions