What is the Devine ideal body weight formula?

The Devine formula, published in 1974 for gentamicin dosing, gives 50 kg for men plus 2.3 kg for every inch of height over 5 feet, and 45.5 kg plus 2.3 kg per inch over 5 feet for women. It is a weight-for-height heuristic, not a measured healthy weight.

Why does the healthy weight range differ from my Devine number?

The two numbers answer different questions. Devine ideal body weight is a fixed height-based estimate from a drug-dosing convention. The healthy weight band is the range of weights that produce a BMI between 18.5 and 24.9 at your exact height, following CDC adult BMI categories. They often differ, and the BMI-based band is the better population screening reference.

Is ideal body weight the same as lean body mass?

No. Lean body mass is the estimated weight of non-fat tissue (muscle, bone, organs, water), while ideal body weight is an empirically derived weight-for-height estimate. The two were historically conflated, but they are different concepts computed from different inputs.

Is the Devine formula a weight-loss target?

No. It was developed as a clinical dosing reference, not as a health goal or diet target. It assumes nothing about body composition, muscle, frame size, or age. Use it as a reference point alongside tools such as BMI or body-composition estimates, and discuss any weight goals with a qualified healthcare professional.

Ideal Body Weight Calculator (Devine)

Ideal body weight (IBW) is a weight-for-height estimate first popularized in clinical practice for drug dosing. This calculator applies the Devine formula from 1974 to your sex and height, and it also shows the BMI calculator healthy weight band for the same height so you can see how the legacy heuristic compares with the population screening range. You can enter your height in centimeters or in feet and inches, and results appear in kilograms or pounds to match.

The Devine number is a single point: one weight for one height and sex. The healthy weight band is a range: every weight that puts your height into a BMI between 18.5 and 24.9, following CDC adult BMI categories. Showing both is deliberate. IBW formulas are decades-old heuristics with real limitations, and a single “ideal” number can be mistaken for a health goal. The range makes the uncertainty visible.

What the calculator shows

The primary result is your Devine ideal body weight, displayed in the unit system you selected. Two supporting readouts follow:

Healthy weight — the weight range at your exact height that corresponds to a BMI of 18.5 to 24.9.
Healthy BMI — the 18.5–24.9 band itself, shown so the range math is transparent.

For a 180 cm man, the Devine result is 75.0 kg while the healthy weight band spans 59.9–80.7 kg. The Devine number sits inside the band, but that is not always the case: at very short or very tall heights the two can disagree noticeably, and the fixed 2.3 kg per inch slope is a simplification.

How the formula works

The Devine formula starts from a base weight at exactly 5 feet (60 inches) and adds a fixed amount per inch of height above that:

Men: 50 kg at 5 ft, plus 2.3 kg per inch over 5 ft.
Women: 45.5 kg at 5 ft, plus 2.3 kg per inch over 5 ft.

The calculator first converts your height to inches. In metric mode it divides centimeters by 2.54; in imperial mode it combines feet and inches directly. It then counts only the inches over 5 feet, so anyone 5 ft or shorter receives the base weight. The result is rounded to one decimal place.

Formula

For a height H in inches:

\text{IBW (men)} = 50 + 2.3 \times \max(0, H - 60)

\text{IBW (women)} = 45.5 + 2.3 \times \max(0, H - 60)

The healthy weight band uses your height in meters (meters = inches × 0.0254):

\text{min healthy weight} = 18.5 \times h^2

\text{max healthy weight} = 24.9 \times h^2

Worked example

Take a man who is 180 cm tall. His height in inches is:

\frac{180}{2.54} = 70.8661

Inches over 5 feet:

70.8661 - 60 = 10.8661

Devine ideal body weight:

50 + 2.3 \times 10.8661 = 74.9921 \text{ kg}

The calculator rounds this to 75.0 kg. His height in meters is 1.80, so the healthy weight band is:

18.5 \times 1.80^2 = 59.94 \text{ kg} \quad\text{to}\quad 24.9 \times 1.80^2 = 80.676 \text{ kg}

Displayed as 59.9–80.7 kg. For a woman who is 5 ft 5 in, the formula gives 45.5 + 2.3 × 5 = 57 kg, or about 125.7 lb — her healthy band is 111.2–149.6 lb.

Interpreting the results

Devine ideal body weight was introduced in a 1974 paper on gentamicin dosing and was later popularized as a general clinical reference. As the Pai and Paloucek review documents, the “ideal” body weight equations were derived from earlier height–weight and insurance tables, not from research on what weight is healthiest, and they were adopted for dosing calculations for which they were not originally designed. The StatPearls “Conversion Weights” chapter notes the same equations and points out that they can overestimate weight at taller heights and underestimate it at shorter heights.

That history matters for interpretation:

It is not a diagnosis or a health goal. A single number cannot capture muscle mass, frame size, age, or medical context.
The healthy band is the screening reference. BMI-based ranges come from population data and are the standard way adult weight categories are communicated, with the caveats that apply to BMI itself.
Body composition is invisible here. Two people of the same height and sex get the same Devine number regardless of lean mass. Tools like the body fat estimate calculator and the waist-to-height ratio calculator look at different signals, and the BMR calculator estimates energy needs from weight, height, and age.

Tips

Enter your height without shoes and round to the nearest centimeter or inch; the formula is linear, so a 1 cm error shifts the result by only about 0.09 kg, but it changes the healthy band endpoints slightly too.
Compare the Devine number with the healthy band rather than treating either as a verdict. A Devine value outside the band is a property of the formula, not a sign that your height is unusual.
If you are using ideal body weight as a dosing reference in a clinical setting, confirm with a pharmacist or clinician which weight convention (actual, ideal, adjusted, or lean) the specific medication protocol requires — it varies by drug.

Common mistakes

Treating the Devine number as a weight-loss target or an “ideal” body. It is a dosing heuristic from 1974.
Confusing ideal body weight with lean body mass. IBW is a height-based estimate; lean mass is a body-composition estimate, and the two terms are historically conflated but not interchangeable.
Forgetting that the formula counts only inches over 5 feet, so someone 5 ft tall and someone 5 ft 6 in do not differ by the full slope.
Reading the healthy weight band as medical advice for a specific person. BMI ranges are population screening bands, not personal prescriptions.

Sources

Pai MP, Paloucek FP, The Origin of the “Ideal” Body Weight Equations (The Annals of Pharmacotherapy, 2000) — documents the Devine equations and the history of IBW as a dosing reference.
StatPearls, Conversion Weights (NCBI Bookshelf) — states the Devine equations and their tendency to over- or underestimate at extreme heights.
CDC, Adult BMI Categories — healthy weight defined as BMI 18.5 to less than 25 for adults.

Ideal Body Weight Calculator (Devine)