Ideal Weight Calculator

How to use this calculator

1. Choose US Units or Metric Units. Switching converts a height you have already typed rather than clearing it.
2. Enter your age and select your gender.
3. Enter your height — feet and inches in US units, centimetres in metric.
4. Press Calculate to see the four ideal-weight estimates side by side, plus the healthy weight range for your height.

Other Units opens a small converter above the calculator. It is not a third unit system: use it when your scales read in stones or your tape reads in metres, then type the converted figure into the boxes. The calculator stays on whichever system you chose.

Why it asks your age

Age changes none of the four formulas — they use height and sex only. It decides whether they apply at all. All four were derived on adults, so below 18 they are the wrong instrument, and the calculator says so instead of printing a number. For children and teenagers, healthy weight is judged from BMI-for-age percentiles, which account for the way body composition changes as a child grows; the BMI calculator is the tool for that.

What "ideal body weight" means

Ideal body weight (IBW) formulas estimate a reference weight from height and sex alone. They were originally devised for clinical purposes such as medication dosing, not as a personal goal. That history is worth remembering: the output is a useful reference point, not a verdict on what you should weigh.

The four formulas

Each formula sets a base weight for a 5-foot (60-inch) frame and adds a fixed amount for every inch above that. They differ only in those two constants. For men, the figures are:

• Robinson (1983): 52 kg + 1.9 kg per inch over 5 ft
• Miller (1983): 56.2 kg + 1.41 kg per inch over 5 ft
• Devine (1974): 50 kg + 2.3 kg per inch over 5 ft
• Hamwi (1964): 48 kg + 2.7 kg per inch over 5 ft

The women's versions use slightly lower base weights and increments. Below 5 ft, each formula falls back to its base weight.

A worked example

For a man who is 5 ft 10 in (10 inches over 5 ft), the four formulas give:

Formula	Estimate
Miller	70.3 kg (155 lb)
Robinson	71.0 kg (157 lb)
Devine	73.0 kg (161 lb)
Hamwi	75.0 kg (165 lb)

Devine, for instance, is 50 + 2.3 × 10 = 73 kg. The four land within about five kilograms of each other — close enough to read as a band rather than four competing answers.

The healthy-BMI range for context

Alongside the formulas, the calculator shows the weights that correspond to a BMI of 18.5 to 25 at your height — the bottom and the top of the healthy band. For 5 ft 10 in that is 128.9 lb to 174.2 lb (about 58.5–79.0 kg): a wider span than the formulas give, and a reminder that healthy weight is a range, not a single point.

Beyond height and sex

These formulas ignore frame size, muscle mass and age, so they fit some bodies better than others. A broad-framed or muscular person can be healthy above the estimates, while a slight frame may sit below them. Use the numbers as a guide, cross-check against the BMI range, and treat neither as a rule.

To screen your current weight against height, use the BMI calculator; to gauge composition rather than weight, see the body fat calculator. This is educational information, not medical advice — talk to a healthcare provider about a target that is right for you.