Fitness · 5 min read
How Ideal Weight Formulas Work
Devine IBW from height — and what the number is not
Ideal body weight (IBW) formulas estimate a reference mass from height and sex. This tutorial walks through the Devine equations used on this site, a 175 cm worked example, and a height slider that places the estimate on a weight band. Devine IBW is a dosing-era estimate, not a healthy-weight target or medical advice.
Written by the My Calculator Stack editorial team. About our methods
Devine ideal body weight is a screening estimate from height and sex, not a diagnosis, healthy-weight range, or medical advice. It does not measure body fat, muscle, or health. Talk to a qualified clinician before using any weight figure for care or dosing.
1.What Devine IBW is
The Devine formula (1974) estimates a reference body weight from height, with a different intercept for male and female. It was built for drug-dosing tables, not as a wellness score. It does not know your muscle, bone, or fat distribution. Treat the number as an estimate only, then talk to a qualified clinician if you need a diagnosis, a target weight, or a care plan.
2.The formula
Height is converted to inches. Inches over 5 ft (60 in) are floored at zero, so shorter statures stay at the base weight. Male: 50 kg + 2.3 kg per inch over 5 ft. Female: 45.5 kg + 2.3 kg per inch over 5 ft. US customary inputs are already inches; metric height in centimeters is divided by 2.54. After that conversion the same equations apply, so Metric and US results stay comparable. The calculator then reports kilograms or pounds to match the unit switch.
\[ \begin{aligned}\mathrm{IBW}_{\mathrm{male}} &= 50 + 2.3\,(\mathrm{in}-60) \\\mathrm{IBW}_{\mathrm{female}} &= 45.5 + 2.3\,(\mathrm{in}-60)\end{aligned} \]
3.Worked example
Take a metric male, height 175 cm — the same default as the ideal-weight calculator. Inches = 175 / 2.54 ≈ 68.90. Inches over 5 ft: 68.90 − 60 = 8.90 (the formula does not floor here because height is above 60 in). Then IBW = 50 + 2.3 × 8.90 ≈ 70.5 kg. The female formula with the same height replaces 50 with 45.5 and gives ≈ 66.0 kg. Neither figure is a healthy-weight band or a diagnosis.
\[ \mathrm{IBW}=50+2.3(175/2.54-60)\approx 70.5 \]
4.Height-slider estimate band
Switch Metric/US and male/female, then move height to see Devine IBW update. The band spans the male and female estimates at that height — a reminder that the formula is sex-specific, not a healthy-weight range. The marker is the selected estimate only. This is a teaching widget — no favorites, no full calculator chrome. Open the ideal-weight calculator when you want the standalone tool.
Inline playground
Devine IBW (estimate only)
70.5 kg
Male 70.5 · female 66.0 kg
50 + 2.3 × (68.90 − 60) ≈ 70.5
Screening aid only — Devine IBW is an estimate from height, not a medical diagnosis, target weight, or treatment plan.
Open the full ideal-weight calculator →5.Open the full calculator
The ideal-weight calculator uses the same Devine equations, the same 175 cm example, and the same screening disclaimer, with How it works, FAQ, and related fitness tools on one page. Browse other fitness calculators if you need BMI, BMR, or body-fat estimates next.
Try it yourself
Open the related calculator and put these formulas to work.