What this ideal weight calculator estimates

The tool compares four height-based equations: Devine, Robinson, Miller and Hamwi, and shows the weight range corresponding to BMI 18.5–24.9. These are reference calculations, not individualized target weights. The main figure is the midpoint of Devine and Robinson. The separate four-formula spread shows the lowest and highest comparison results.

Traditional ideal-body-weight equations have roots in drug dosing and historical height-weight tables. Robinson and colleagues’ 1983 paper describes deriving equations for dosage calculations. A later research paper on ideal weight and BMI discusses the history and differences between these approaches.

The formulas used in this tool

Let X be the number of inches above 5 feet (152.4 cm). Devine, Robinson and Miller give kilograms. Hamwi below gives pounds, converted with 1 lb = 0.45359237 kg.

Height-based weight equations
Equation	Male	Female
Devine	50 + 2.3 × X	45.5 + 2.3 × X
Robinson, commonly used rounded version	52 + 1.9 × X	49 + 1.7 × X
Miller (kg)	56.2 + 1.41 × X	53.1 + 1.36 × X
Hamwi (lb)	106 + 6 × X	100 + 5 × X

The Robinson coefficients used here are the common rounded calculator version. They are not the exact regression coefficients printed in the original paper, so results can differ slightly from an implementation of the original regression.

Illustrative weight estimates by height

Devine estimates beside an adult BMI-based range
Height	Devine, male	Devine, female	BMI 18.5–24.9 range
160 cm	56.9 kg	52.4 kg	47.4–63.7 kg
165 cm	61.4 kg	56.9 kg	50.4–67.8 kg
170 cm	65.9 kg	61.4 kg	53.5–72.0 kg
175 cm	70.5 kg	66.0 kg	56.7–76.3 kg
180 cm	75.0 kg	70.5 kg	59.9–80.7 kg
185 cm	79.5 kg	75.0 kg	63.3–85.2 kg

The BMI column uses the same arithmetic for both sexes. It does not account for muscle mass, body proportions, medical conditions or individual health needs.

Worked example: 175 cm

175 cm is 68.90 inches, or about 8.90 inches above five feet. For the male equations, Devine gives 70.5 kg and the rounded Robinson formula gives 68.9 kg. Their midpoint is 69.7 kg. Miller gives 68.7 kg and the pounds-based Hamwi equation gives 72.3 kg. The four-formula spread is 68.7–72.3 kg, which describes disagreement between the equations. The BMI-based range is about 56.7–76.3 kg.

Why an “ideal” number is not a prescription

These formulas cannot tell you how much you should weigh, what your body composition is or whether a weight change is appropriate. A clinician considers more information than height and sex. Do not use this educational calculator to dose medication.

Below 152.4 cm, this tool does not extend the “inches above five feet” formulas or pretend they apply unchanged. It shows the BMI-based range and marks all four height-based formulas as unavailable. The adult BMI interpretation is intended for ages 20 and older.

Use the BMI calculator to see the category for your current height and weight. The body fat calculator estimates a different measure using a tape; the calorie calculator estimates daily energy needs.

Why Hamwi can differ between calculators

This tool implements Hamwi’s pounds-based equations, as reproduced in Peterson and colleagues’ comparison of ideal-weight equations, Table 3. Some calculators use rounded kilogram coefficients, which can give a slightly different answer. The formula table states the version used here.

A wider spread does not establish which formula suits you. It shows how much the choice of equation changes the result for the same inputs. None measures body composition or supplies an individual target weight.

Copy or print your calculation

Open How your result is calculated to see the arithmetic for your current inputs. The steps use the same equation as the result; intermediate numbers are rounded for reading.

Copy results includes inputs, labelled results, calculation steps and notes. Print / save PDF opens a report preview, then your browser’s print options. Choose Save as PDF if your browser supports it. Check the report before sharing: it contains the measurements you entered. Reset example restores the sample values while keeping your main measurement units. These actions run on your device; the tool does not keep a calculation history.

Common questions

Why do Devine and Robinson give different weights?

They use different starting values and increments per inch. Neither establishes a uniquely correct weight for an individual.

Is the midpoint my target weight?

No. It is the arithmetic average of two formula estimates, shown for comparison. It is not a recommendation to gain or lose weight.

Can I enter feet and inches?

Yes. Select feet and inches for height. Select kilograms or pounds separately for the results.

What happens below five feet?

The tool shows the adult BMI-based range and withholds all four height-based formula results rather than extending the equations below their reference height.

Does age affect these equations?

These four equations do not contain age. That does not mean age is irrelevant to health or weight assessment. These are adult educational calculations.

Written and maintained by Rowan Hale, the site author’s pen name. Updated September 13, 2026. No medical or dietetic qualification is claimed. Read our editorial policy or report a calculation error.

Ideal Weight Calculator