Why do Devine and Robinson disagree?

Different calibration data and per-inch slopes (2.3 vs 1.9 lb/in for men). Both persist in medicine for historical reasons; neither is "correct".

Is my ideal weight the weight I should chase?

Not necessarily. These formulas ignore composition and history. Many people are healthiest outside their formulaic IBW.

Do the formulas work under five feet?

They degenerate toward the flat base weight and were never validated there; the calculator rejects very short heights rather than mislead.

Health

Ideal Weight Calculator

What this does

See ideal body weight estimates from the Devine and Robinson clinical formulas for your height and sex, presented side by side in kilograms.

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How to use it

Using the ideal weight calculator

01
Select sex and enter height
Centimetres please; the formulas internally work in inches above five feet.
02
Read both estimates
Devine is the classic clinical standard; Robinson tracks mid-century desirable-weight tables.
03
Interpret with context
Treat the range as a rough reference point; healthy-BMI ranges and body composition tell you more personally.

Good to know

Formulas built for prescriptions, not mirrors

Devine’s 1974 paper literally titled itself about dosing. Clinicians still use IBW to size drug loads and tidal volumes because those depend on lean body compartments; which is why the numbers can feel oddly specific yet personally irrelevant.

Frame size was always missing

Mid-century insurance tables distinguished small, medium and broad frames; the simplified formulas dropped that axis entirely. Two siblings of identical height with different shoulder widths legitimately carry different healthy weights.

Better personal anchors

Your own stable historical weight at good habits.
A healthy BMI weight window for your height.
Body-composition measures (Navy method, DEXA) over scale weight alone.

How it's calculated

The math behind this calculator

Devine:   men 50 + 2.3·(inches over 5 ft)    women 45.5 + 2.3·(inches over 5 ft)
Robinson: men 52 + 1.9·(inches over 5 ft)    women 49 + 1.7·(inches over 5 ft)

Both formulas assign a base weight at exactly five feet and add a fixed amount per inch above it. Devine (1974) was created for dosing medications like digoxin; Robinson and peers recalibrated the constants against desirable-weight insurance tables.

Because the formulas disagree by several kilograms, we display both plus the span between them; a reminder that "ideal" weight is a dosing concept, not a destiny.

Assumptions & limitations

Adults taller than five feet; heights below 140 cm are rejected.
Does not consider frame size, muscle mass or body composition.
Clinical context is drug dosing and ventilator settings, not aesthetics.

Worked example

For a 175 cm man the Devine formula suggests about 70.5 kg, while Robinson lands nearer 68.9 kg; both within the same healthy-BMI window.

FAQ

Frequently asked questions

Why do Devine and Robinson disagree?: Different calibration data and per-inch slopes (2.3 vs 1.9 lb/in for men). Both persist in medicine for historical reasons; neither is "correct".
Is my ideal weight the weight I should chase?: Not necessarily. These formulas ignore composition and history. Many people are healthiest outside their formulaic IBW.
Do the formulas work under five feet?: They degenerate toward the flat base weight and were never validated there; the calculator rejects very short heights rather than mislead.

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