Ideal Body Weight Calculator

Determine your healthy weight range based on height and frame size using four major scientific formulas.

What is Ideal Body Weight (IBW)?
IBW formulas were originally developed for clinical settings - specifically to calculate safe medication dosages in patients, not to define an aesthetic goal or a "perfect" weight. They estimate a target weight based on height and gender only. They do not account for muscle mass, bone density, age, or fitness level. Use this tool as a general reference, not a personal health prescription.

Biological Sex The IBW formulas differ by biological sex due to differences in bone structure.

Height

ft in

Height (cm)

Wrist Circumference (optional - for frame size) Measurement in inches

Wrist Circumference (optional - for frame size) Measurement in cm

How to measure your wrist circumference: Use a soft measuring tape and wrap it around your wrist just below the wrist bone (the protruding bone on the pinky side). Keep the tape snug but not tight. This measurement determines your body frame size: Small, Medium, or Large. Frame size adjusts the calculated weight by plus or minus 10 percent.

Your Results

Recommended Weight Range

Aggregated across four scientific formulas

Formula Breakdown

Devine Formula

J. Devine, 1974

The most widely used clinical standard. Originally developed for drug dosage calculations in hospitals. Uses a fixed base weight with an increment per inch above 5 feet.

Robinson Formula

J. Robinson, 1983

A popular modification of the Devine formula that uses slightly different base weights and per-inch increments. Often considered more accurate for taller individuals.

Miller Formula

D. Miller, 1983

Known for producing more moderate estimates at the extreme ends of the height range. Uses a smaller height increment, making it gentler for very tall people.

Hamwi Formula

G. Hamwi, 1964

One of the earliest IBW formulas. Commonly used in diabetes care and nutritional counseling. Uses a larger per-inch increment than Devine, giving higher estimates for taller people.

Healthy BMI Reference Range (18.5 - 24.9)

This is the weight range that places you in the "Normal" BMI category. BMI is a population-level screening tool and does not account for muscle mass, body composition, or ethnicity.

Important: These results are for general informational purposes only and are not a substitute for professional medical advice. IBW formulas do not account for age, muscle mass, fat distribution, fitness level, or individual health conditions. Always consult a qualified healthcare provider before making decisions about your weight or diet.

Understanding Ideal Body Weight Formulas

"Ideal body weight" (IBW) is not a single number but an estimated range produced by mathematical formulas that were originally developed for clinical purposes, most notably to help doctors and pharmacists calculate accurate medication dosages. The four formulas used by this calculator (Devine, Robinson, Miller, and Hamwi) were each created decades apart by different researchers, and they all share the same basic structure: a fixed base weight assigned to a height of 5 feet, plus a fixed increment added for every inch over that height. The differences between the formulas come down to how large that base weight and per-inch increment are, which is why the same height can produce slightly different results across formulas.

Because no single formula is universally "correct," this tool averages all four to give you a realistic range rather than one rigid target. The healthy BMI reference range is also included as a second point of comparison, since BMI uses an entirely different calculation method (weight divided by height squared) and is the most widely cited population-level screening tool.

Original insight: One detail many calculators leave out is that none of these formulas were designed with muscular or highly active individuals in mind. The Devine formula, for example, was created in 1974 specifically to estimate drug distribution volume, not to define a "healthy" weight. If you are very muscular, your ideal body weight may sit well above the formula range without any negative health implications, because muscle tissue weighs more than fat tissue at the same volume. For this reason, IBW results should always be read alongside frame size, body composition, and how you actually feel and perform, rather than treated as a strict target to chase.

Key Terms Explained

Ideal Body Weight (IBW)

An estimated weight range calculated from height (and sometimes frame size) using one of several clinical formulas. Originally developed for medical dosing calculations, not as a personal fitness goal.

Body Frame Size

A classification (small, medium, or large) based on wrist circumference relative to height. It is used to adjust the IBW estimate up or down by roughly 10 percent to account for differences in bone structure.

Body Mass Index (BMI)

A screening measurement calculated by dividing weight by height squared. The "normal" BMI range of 18.5 to 24.9 is shown here as an additional reference point alongside the formula-based IBW range.

Adjusted Body Weight (ABW)

A separate clinical calculation sometimes used for individuals well above their IBW, particularly in medication dosing. It blends actual body weight with ideal body weight to better estimate how a drug will distribute through the body.

Frequently Asked Questions

Why do the four formulas give slightly different results?

Each formula was developed independently using different reference populations and assumptions about base weight and per-inch increments. The Robinson formula tends to run slightly lower than Hamwi for taller individuals, for example. None is definitively more "correct" than the others, which is why this tool presents all four alongside an averaged range.

Does ideal body weight apply to athletes or very muscular people?

Not directly. These formulas only account for height (and optionally frame size), not muscle mass or body composition. A muscular athlete can weigh significantly more than their IBW range while still being lean and healthy. Body fat percentage and waist circumference are generally more useful measures for athletic populations.

How does frame size change my result?

If you enter your wrist circumference, the calculator classifies your frame as small, medium, or large based on the ratio of wrist size to height. A small frame typically reduces the IBW estimate by about 10 percent, while a large frame increases it by about 10 percent, since people with larger bone structures naturally carry more weight at a healthy level.

Should I use IBW or BMI to judge my weight?

Both are screening tools, not diagnoses. BMI is simpler and widely used in research, but it does not distinguish between muscle and fat. IBW formulas give a height-based weight range that some clinicians find more intuitive for everyday goal-setting. Using both together, alongside body composition measurements, gives a more complete picture than relying on either alone.