Why does this calculator show four different numbers instead of one?

Because no single formula is universally accepted as 'the' correct one — Devine, Robinson, Miller, and Hamwi are four different clinical formulas developed decades apart, each with slightly different coefficients. Showing the full range (and their average) is more honest than presenting one number as definitive.

Where do these formulas actually come from?

All four were originally developed for medical purposes — primarily to estimate a reference body weight for calculating medication dosages, not as fitness or aesthetic targets. Devine's formula (1974) is the most widely used in clinical practice today, often for drug dosing calculations in hospitals.

Is 'ideal body weight' the same as a healthy weight?

Not exactly — these formulas only use height and sex, while actual health depends heavily on body composition, muscle mass, bone density, and overall fitness, none of which a height-only formula can capture. A muscular athlete can weigh well above their 'ideal body weight' range and be perfectly healthy.

What does frame size do to the result?

Selecting a small or large frame applies a roughly 10% downward or upward adjustment to account for differences in bone structure between individuals of the same height. It's an approximation, not a precise measurement — actual frame size is sometimes assessed clinically using wrist circumference relative to height.

Should I use this instead of BMI?

They answer different questions. BMI relates weight to height as a single ratio and is used for broad population screening. Ideal body weight formulas estimate a specific target weight in pounds or kilograms, historically for medical dosing. Neither fully captures individual health — our BMI Calculator and Body Fat Calculator offer complementary perspectives.

Is my data stored anywhere?

No. All calculations run locally in your browser. Nothing you enter is transmitted to a server or stored.

AI Insights

Ideal Body Weight Calculator

Estimate your ideal body weight range from height and sex using four standard clinical formulas (Devine, Robinson, Miller, Hamwi).

Last updated August 30, 2026

Height

Frame size (optional)

Ideal weight range

129.4–135.1 lbs

58.7–61.3 kg · average 131.4 lbs

Formula	Estimate
Devine	130.7 lbs (59.3 kg)
Robinson	130.5 lbs (59.2 kg)
Miller	135.1 lbs (61.3 kg)
Hamwi	129.4 lbs (58.7 kg)

These classic formulas were originally designed to help physicians calculate safe medication dosages rather than to define a personal health or fitness target. Seeing a spread between the different calculations is completely normal because each equation relies on a slightly different mathematical approach to height. Ultimately, a single number on a scale cannot measure muscle mass, bone density, or how a person feels in their everyday life.

AI-generated insight

These formulas were developed as reference weights for medical dosing, not fitness or cosmetic targets — a healthy weight for you personally depends on much more than height and sex alone.

How to use the ideal body weight calculator

1
Select male or female.
2
Enter your height in feet/inches or centimeters.
3
Optionally select a frame size for a refined estimate.
4
Your weight range and each individual formula's estimate update instantly.

How the four formulas work

Height and sex feed into four separate clinical formulas, whose results combine into a range and average estimate.

Each formula follows the same basic pattern — a base weight at 5 feet tall, plus a fixed amount per inch over that — but the specific coefficients differ:

Devine (women) = 45.5 + 2.3 × (height in inches − 60)

Worked example: a 5'6" (66 in) woman with a medium frame: Devine gives 59.3 kg (130.7 lbs), Robinson gives 59.2 kg (130.5 lbs), Miller gives 61.3 kg (135.1 lbs), and Hamwi gives 58.7 kg (129.4 lbs) — averaging to about 59.6 kg (131.4 lbs), with the full range spanning 129.4–135.1 lbs.

The roughly 6-pound spread across formulas isn't a sign that any one is "wrong" — it reflects genuine differences in how each was originally derived, which is exactly why showing a range is more honest than picking one formula and presenting it as definitive.

Ideal weight vs. BMI

BMI relates your weight to your height as a single ratio, used mainly for broad population-level screening. Ideal body weight formulas instead estimate an actual target weight in pounds or kilograms — historically developed for medical drug dosing, not as a fitness or cosmetic goal. Neither on its own accounts for muscle mass, bone density, or overall body composition, which is why a combination of tools gives a fuller picture than any single number.

Compare against our BMI Calculator and Body Fat Calculator for a more complete view.

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