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Ideal Weight Calculator

HealthHeight, Weight and Growth
Sex
Units
Ideal weight (Devine formula) —
Robinson formula
—
Miller formula
—
Hamwi formula
—
Range across the four formulas
—
Weight for BMI 18.5–24.9
—

Ideal body weight formulas start from a base weight at 5 ft and add a fixed amount per inch above it. The Devine formula, the one most used in clinical dosing, gives men 50 kg plus 2.3 kg per inch and women 45.5 kg plus 2.3 kg per inch. A man of 5 ft 10 in gets 73.0 kg.

About this tool

Ideal body weight equations come from pharmacology and insurance tables, not from a measure of health. Clinicians still use them to dose some drugs and to set ventilator volumes, and many people use them as a rough target. This calculator takes your sex and height in centimetres or feet and inches, and returns the Devine result along with the Robinson, Miller and Hamwi formulas, the spread between them, and the weight range that keeps your BMI between 18.5 and 24.9. Each formula's arithmetic is shown. The formulas ignore frame size, muscle mass and age, and they were fitted for adults about 5 ft and taller, so treat any single figure as an estimate within a band of several kilograms.

How to use it

  1. Pick sex

    Each formula uses a different base weight and slope for men and women.

  2. Choose units and enter height

    Use centimetres in metric, or feet and inches in US units; results show in kg or lb to match.

  3. Compare the formulas

    Read the Devine figure first, then the range across all four and the BMI-based range.

Examples

Man, 177.8 cm (5 ft 10 in)

Sex
Male
Units
Metric (cm, kg)
Height
177.8

Result Ideal weight (Devine formula): 73.0 kg
Robinson formula: 71.0 kg
Miller formula: 70.3 kg
Hamwi formula: 75.0 kg
Range across the four formulas: 70.3 kg – 75.0 kg
Weight for BMI 18.5–24.9: 58.5 kg – 78.7 kg

  1. Height = 70 in, which is 10 in from 5 ft (60 in)
  2. Devine: 50 + 2.3 × 10 = 73 kg
  3. Robinson: 52 + 1.9 × 10 = 71 kg
  4. Miller: 56.2 + 1.41 × 10 = 70.3 kg
  5. Hamwi: 48 + 2.7 × 10 = 75 kg
  6. Healthy BMI 18.5–24.9 at 1.778 m = 58.5 kg to 78.7 kg

Ten inches over 5 ft adds 23 kg to the Devine base of 50 kg. Miller gives the lightest figure and Hamwi the heaviest.

Woman, 165.1 cm (5 ft 5 in)

Sex
Female
Units
Metric (cm, kg)
Height
165.1

Result Ideal weight (Devine formula): 57.0 kg
Robinson formula: 57.5 kg
Miller formula: 59.9 kg
Hamwi formula: 56.5 kg
Range across the four formulas: 56.5 kg – 59.9 kg
Weight for BMI 18.5–24.9: 50.4 kg – 67.9 kg

  1. Height = 65 in, which is 5 in from 5 ft (60 in)
  2. Devine: 45.5 + 2.3 × 5 = 57 kg
  3. Robinson: 49 + 1.7 × 5 = 57.5 kg
  4. Miller: 53.1 + 1.36 × 5 = 59.9 kg
  5. Hamwi: 45.5 + 2.2 × 5 = 56.5 kg
  6. Healthy BMI 18.5–24.9 at 1.651 m = 50.4 kg to 67.9 kg

Five inches over 5 ft: Devine gives 45.5 + 2.3 × 5 = 57.0 kg, and the other formulas land within about a kilogram of it.

Man, 5 ft 10 in, in pounds

Sex
Male
Units
US (ft, in, lb)
Height
5
and
10

Result Ideal weight (Devine formula): 160.9 lb
Robinson formula: 156.5 lb
Miller formula: 155.0 lb
Hamwi formula: 165.3 lb
Range across the four formulas: 155.0 lb – 165.3 lb
Weight for BMI 18.5–24.9: 128.9 lb – 173.5 lb

  1. Height = 70 in, which is 10 in from 5 ft (60 in)
  2. Devine: 50 + 2.3 × 10 = 73 kg
  3. Robinson: 52 + 1.9 × 10 = 71 kg
  4. Miller: 56.2 + 1.41 × 10 = 70.3 kg
  5. Hamwi: 48 + 2.7 × 10 = 75 kg
  6. Healthy BMI 18.5–24.9 at 1.778 m = 128.9 lb to 173.5 lb

The same 73 kg Devine result shown in pounds, with Robinson at 71 kg or about 156.5 lb.

How it is calculated

IBW = base + slope × (height in inches − 60)

base
weight at 5 ft: Devine 50 / 45.5 kg, Robinson 52 / 49, Miller 56.2 / 53.1, Hamwi 48 / 45.5 (men / women)
slope
kg per inch: Devine 2.3 / 2.3, Robinson 1.9 / 1.7, Miller 1.41 / 1.36, Hamwi 2.7 / 2.2
height
height in inches; centimetres are divided by 2.54

All four equations are linear in height above 60 inches and differ only in their constants. Devine (1974) was proposed for gentamicin dosing; Robinson and Miller (both 1983) were later refits to life-insurance data; Hamwi (1964) came from diabetes practice. The BMI range is weight = BMI × height in metres squared at 18.5 and 24.9. Pounds are kilograms divided by 0.45359237.

Sources

When not to use it

  • For children and teenagers, growth is judged on age- and sex-specific charts, not adult weight equations.
  • For very muscular people the formulas understate a healthy weight, because they know nothing about body composition.
  • For heights under 5 ft the equations extrapolate below their fitted range and can give implausibly low values.

Common mistakes

  • Treating one formula's figure as an exact target when the four formulas often disagree by 5 kg or more.
  • Typing height in metres into the centimetre field, which falls outside the allowed range.
  • Confusing ideal body weight with adjusted body weight, which clinicians use for some drug doses in obesity.

Frequently asked questions

Why do the four formulas give different answers?

Each was fitted to a different population and purpose. Devine was a dosing rule of thumb, Robinson and Miller were derived from Metropolitan Life height-weight tables, and Hamwi came from diabetes diet planning. Their slopes differ, so the gap widens the further your height is from 5 ft.

Which formula do hospitals use?

Devine is the one most often built into clinical calculators, for example for aminoglycoside dosing and for setting tidal volume in ventilated patients. That is why this calculator reports it as the headline figure.

How does ideal weight relate to BMI?

For most adult heights, Devine values fall around a BMI of 21 to 23, inside the 18.5 to 24.9 range. The BMI range shown here is wider and is often a more practical goal than any single formula figure.

Do the formulas account for age or body frame?

No. They use only sex and height. Older insurance tables split results by small, medium and large frames, but these equations average over those, so a broad-framed person may sit well above the figure and still be healthy.

What happens below 5 feet?

The formulas subtract the per-inch amount for every inch under 60, which was never part of how they were fitted. The calculator still shows a value but adds a note that it is an extrapolation.

Cite this tool

Using this tool in an assignment, article or report? Copy a citation, or a link for your website.

APA

Tools Directory Editorial Team. (2026, October 9). Ideal Weight Calculator. Tools Directory. Retrieved October 28, 2026, from https://tools.milunir.com/health/height-weight-and-growth/ideal-weight-calculator/

MLA

Tools Directory Editorial Team. “Ideal Weight Calculator.” Tools Directory, 9 Oct. 2026, https://tools.milunir.com/health/height-weight-and-growth/ideal-weight-calculator/. Accessed 28 Oct. 2026.

Chicago

Tools Directory Editorial Team. “Ideal Weight Calculator.” Tools Directory. Last modified October 9, 2026. Accessed October 28, 2026. https://tools.milunir.com/health/height-weight-and-growth/ideal-weight-calculator/.

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