Ideal Body Weight Calculator (3 Formulas)
Compare ideal body weight estimates from the Devine, Robinson, and Miller formulas side by side for your height and sex.
How to use this tool
- Enter height and sex in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your devine ibw and the full breakdown beneath it.
Educational estimate — not medical advice. Consult a clinician.
Three widely-used clinical formulas estimate ideal body weight (IBW) from height and sex. Originally developed for drug dosing, they should not be used as aesthetic targets. All formulas apply only to heights above 5 feet (152 cm); they are unreliable below that threshold.
Formula
Height in inches (Hin) = height (cm) ÷ 2.54; excess inches = Hin − 60
Devine: IBW = 50.0 (male) / 45.5 (female) + 2.30 × excess
Robinson: IBW = 52.0 (male) / 49.0 (female) + 1.90 (male) / 1.70 (female) × excess
Miller: IBW = 56.2 (male) / 53.1 (female) + 1.41 (male) / 1.36 (female) × excess
All results in kg; excess inches is the number of inches above 5 feet (60 inches).
How it works
Three widely published empirical formulas — Devine (1974), Robinson (1983), and Miller (1983) — estimate ideal body weight in kg from height and sex by starting from a base weight at 5 feet (60 inches) and adding a fixed increment per additional inch of height. Each formula was derived from different actuarial or pharmacokinetic datasets, which is why they diverge, particularly at heights far from 5 feet. This calculator converts height from centimetres to inches, computes excess inches above 60, and applies all three formulas simultaneously so users can see the range of estimates; no single formula is universally accepted, and IBW is most commonly used for drug-dosing calculations rather than weight-loss goals.
Worked example
Worked example
- Inputs: height = 170 cm, sex = male.
- Height in inches = 170 ÷ 2.54 = 66.93 inches; excess = 66.93 − 60 = 6.93 inches.
- Devine IBW = 50.0 + 2.30 × 6.93 = 50.0 + 15.94 = 65.94 kg.
- Robinson IBW = 52.0 + 1.90 × 6.93 = 52.0 + 13.17 = 65.17 kg.
- Miller IBW = 56.2 + 1.41 × 6.93 = 56.2 + 9.77 = 65.97 kg.
Devine = 65.94 kg, Robinson = 65.17 kg, Miller = 65.97 kg.
Key terms
- Ideal body weight (IBW)
- An estimated target weight for a given height and sex, originally derived from life-insurance mortality data; widely used in medicine for drug-dosing calculations.
- Devine formula
- The most commonly used IBW equation (1974), developed to guide drug dosing and based on population weight data; base weight 50 kg (male) or 45.5 kg (female) at 5 feet.
- Robinson formula
- A 1983 IBW equation with a higher base weight than Devine but a smaller increment per inch; tends to give slightly lower estimates for taller individuals.
- Miller formula
- A 1983 IBW formula with the highest base weight of the three but the smallest per-inch increment; converges with Devine and Robinson around average heights.
- Excess inches
- The number of inches of height above 60 inches (5 feet); all three IBW formulas start from a base weight at 5 feet and add a fixed amount per excess inch.
Frequently asked questions
- Which IBW formula is most accurate?
- All three are approximations from the 1960s–1980s and have similar accuracy. The Devine formula is most commonly used in clinical dosing (e.g., tidal volume in mechanical ventilation). Robinson and Miller tend to give slightly lower estimates.
- Should I use IBW as a weight-loss target?
- No. IBW formulas were designed for drug dosing, not body composition targets. A healthy weight range based on BMI, body fat percentage, and clinical assessment is more appropriate.
- What if my height is below 5 feet (152 cm)?
- These formulas use (height_in − 60) as the excess-height term, so they are not valid below 60 inches (152 cm). Consult a clinician for dosing needs in that range.