Ideal Weight Calculator — Devine, Robinson, Miller, Hamwi

How it works

Every "ideal weight" formula has the same shape — a base weight at 5 feet plus a fixed amount per inch above it — and they differ only in the numbers. Devine (1974) was built for drug dosing, not health, and Robinson, Miller, and Hamwi are later re-fits; on the same person they can land a few kilograms apart, which is the honest signal that "ideal weight" is a construct, not a measured target. Sex shifts the base down for women. Because these formulas ignore build, muscle, and frame, this page also shows the healthy-weight range from BMI (18.5–25 × your height in metres squared) — a range, not a point, and the one grounded in health outcomes rather than a dosing convention.

Worked example

For a man 170 cm (66.9 inches) tall, that's 6.9 inches over 5 feet. Devine gives 50 + 2.3 × 6.9 ≈ 65.9 kg; Robinson 64.5 kg; Miller 66.0 kg; Hamwi 66.7 kg — a spread of about 2.2 kg. The healthy-BMI range for 170 cm is 18.5 × 1.70² = 53.5 kg to 25 × 1.70² = 72.3 kg. A woman of the same height starts about 4.5 kg lower on Devine, from the lower base weight.

Frequently asked questions

What is "ideal body weight"?

A weight estimated from height and sex by a formula — originally, in Devine's case, to standardise drug doses, not to define health. It's a single number, but because different formulas give different answers and none accounts for your build, it's better read as a rough anchor than a goal. The healthy-BMI range is the more meaningful reference.

Which formula is right?

None is uniquely "right" — they're different statistical fits. Devine is the most cited and the default here; Robinson and Miller were later refinements, Hamwi is a quick clinical rule of thumb. They agree within a few kilograms for most heights. If a specific setting (a hospital, a dosing protocol) uses one, match that; otherwise treat the cluster as a range.

Should I aim for my "ideal weight"?

Not as a strict target. These formulas don't know your muscle mass, frame size, or body composition, so a fit, muscular person can be "above ideal weight" and perfectly healthy. Use the healthy-BMI range as a band to be roughly within, and consider waist measurements and body-fat percentage alongside weight. This page informs; it doesn't prescribe a goal.

Why is the number different for men and women?

The formulas use a lower base weight for women — for Devine, 45.5 kg versus 50 kg at 5 feet — reflecting average differences in build and body composition. The per-inch increment is the same or slightly lower. It's a population average, so an individual can sit either side regardless of sex.

What's the healthy-weight range shown alongside?

It's the weight range that puts your BMI between 18.5 and 25 — the WHO healthy-weight band — for your height. Unlike the ideal-weight formulas, it's grounded in health-outcome data and is expressed as a range rather than a single figure, which is a more honest way to think about a target weight.

Does frame size change ideal weight?

The classic formulas don't include frame size, though some older charts adjusted for it. A larger frame carries more weight healthily, a smaller frame less, so two people of the same height can have genuinely different healthy weights. Treat the formulas as unadjusted averages; your frame is one reason the range matters more than the point.

How accurate is this, and what does it exclude?

The formulas are exact for the height and sex entered, but they estimate a convention, not a health outcome, and they exclude age, muscle, body fat, frame, and ethnicity. Don't use them as a weight goal; use them for context and lean on the healthy-BMI range, waist metrics, and a professional's judgment for anything health-related.