Ideal Weight Calculator

This ideal weight calculator compares four classic formulas and shows the healthy BMI weight range. Ideal body weight formulas estimate a healthy weight from your height and sex. They were originally built for medical dosing, and each gives a slightly different answer. This calculator shows four of them together, plus the weight range for a healthy BMI, so you get a realistic target rather than a single rigid number.

The formulas

All four add a base weight to an amount per inch over five feet:

Devine (men):    50.0 kg + 2.3 kg per inch over 5 ft
Robinson (men):  52.0 kg + 1.9 kg per inch over 5 ft
Miller (men):    56.2 kg + 1.41 kg per inch over 5 ft
Hamwi (men):     48.0 kg + 2.7 kg per inch over 5 ft

Women use a lower base with a similar slope.

Use the range

Because these formulas ignore muscle and frame, the healthy BMI range for your height (a BMI of 18.5 to 24.9) is usually the better guide. Most people find their real target sits somewhere within it.

Worked example

A man 175 cm tall is 68.9 inches, which is 8.9 inches over five feet:

Devine:    50.0 + 2.3 × 8.9   ≈ 70.5 kg
Robinson:  52.0 + 1.9 × 8.9   ≈ 68.9 kg
Miller:    56.2 + 1.41 × 8.9  ≈ 68.7 kg
Hamwi:     48.0 + 2.7 × 8.9   ≈ 72.0 kg
healthy BMI range (18.5–24.9) ≈ 56.7 – 76.3 kg

Four respected formulas give four answers spanning 3.3 kg, and the BMI window is nearly 20 kg wide. The honest conclusion is not that one of them is right — it is that height alone does not determine a healthy weight, and any single figure printed as the ideal one is overselling what height can tell you.

Where these formulas came from

All four were built for medical dosing, not for appearance and not for setting a personal target. The Devine equation of 1974 exists to estimate drug clearance, and the others are refinements of the same idea. That origin explains their shape: they need a rough weight from a measurement a clinician can take in seconds, and they were never validated against health outcomes.

It also explains what they ignore. Muscle mass, bone density, frame size, body composition, and where fat is distributed all affect health, and none of them appear in the arithmetic. A muscular person and a sedentary one of the same height receive an identical answer, which is the clearest sign that the number should not be treated as a goal.

A limitation worth knowing about

Every formula here computes an increment per inch over five feet, and that increment is floored at zero. If you are shorter than 5 ft all four return their base weight — 50.0, 52.0, 56.2 and 48.0 kg for men, and 45.5, 49.0, 53.1 and 45.5 kg for women — however far below it you are. A person of 4 ft 8 in therefore receives the same figure as one of exactly 5 ft.

That is a property of the published equations rather than a defect in this implementation, but it means the results are least useful for shorter adults. For anyone under five feet the BMI range on the same page is a considerably better guide, since it scales with the square of your actual height instead of assuming you clear a fixed threshold. BMI Calculator computes that range directly, and Body Fat Calculator brings composition into view, which none of these four formulas can see.

Private and precise

This calculator produces estimates from published formulas and is not medical advice. For anything about your health, talk to a doctor or a registered dietitian.