What is ideal body weight?

A reference weight for a given height and sex, originally developed for medication dosing and nutrition screening. It is a convention with a clinical lineage — not a scientifically discovered perfect weight for your body.

Which IBW formula should I use?

Devine is the most cited and the usual default in pharmacy references. Robinson, Miller, and Hamwi give close but different answers, which is exactly why this tool shows all four: the honest takeaway is a range, not one number.

What happens below 5 feet tall?

The standard equations add nothing below 60 inches, so they simply hold the base weight — a known weakness. Shorter adults are better served by BMI ranges or dedicated adjustment methods with clinical guidance.

Does frame size change the answer?

The classic workaround is to widen the formula result by about ±10% for small and large frames, shown here as a band. It is a rough heuristic; no calculator can measure your actual skeletal structure.

Is IBW the same as a healthy weight range?

No. IBW formulas produce one narrow number, while the BMI healthy band for the same height typically spans 15–20 kg (30–45 lb). Plenty of muscular, healthy people sit well above their “ideal” number.

Should I try to reach my IBW?

Not as a mission. Health markers — blood pressure, lipids, glucose, fitness, waist circumference — matter more than matching a 1974 dosing table. If a clinician is using IBW to dose a medication, let them run that number.

Ideal Body Weight Calculator | Online Calculators Free

What “ideal body weight” means

The IBW formulas were never fitness targets. B. J. Devine published his 1974 equation to dose drugs like digoxin and theophylline, where a standard weight for a given height was clinically handy; Robinson, Miller, and Hamwi followed with rival coefficients. All four start from a base weight at 5 feet and add a fixed amount per inch over it — which makes them simple, dated, and blind to body composition.

Four formulas, one height

Devine: 50 kg (men) or 45.5 kg (women) + 2.3 kg per inch over 5 ft. Robinson: 52 / 49 + 1.9 / 1.7. Miller: 56.2 / 53.1 + 1.41 / 1.36. Hamwi: 48 / 45.5 + 2.7 / 2.2. Under 5 feet the additions clamp at zero — the classic equations simply hold the base weight, one of their known limits for shorter people.

How to actually use it

The traditional frame-size adjustment widens the answer by ±10%, which this tool shows as a band. For a reality check, compare it with the BMI 18.5–24.9 range for your height — if your real weight sits inside that range, the formula number is trivia, not a to-do. Medication dosing and clinical nutrition decisions belong with a professional who can see the whole chart.

Worked example

A woman, 165 cm tall — that is about 5 ft 5 in (64.96 in).
Inches over 5 ft: 64.96 − 60 = 4.96.
Devine: 45.5 + 2.3 × 4.96 = 56.9 kg (≈125 lb).
The BMI range for 1.65 m runs 50.4–67.8 kg — a far wider healthy span.

How to use it

Pick metric or imperial (imperial height is total inches — 5 ft 5 in = 65).
Enter sex and height.
Read the Devine ideal weight with Robinson, Miller, and Hamwi alongside.
Compare the ±10% frame band with the BMI healthy range before drawing conclusions.