Ideal Body Weight Calculator
See what four major medical formulas say your ideal weight should be — then understand why athletes and gym-goers often should ignore these numbers.
Calculate Your Ideal Body Weight
Average Ideal Body Weight
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lbs (average of all 4 formulas)
All Four Formulas
Important Note for Athletes
These formulas were developed for general medical use and do not account for muscle mass. A 5'10" bodybuilder with 190 lbs of lean, athletic physique will be told they are "overweight" by these formulas. If you train regularly, your ideal weight is better determined by your target body fat percentage, not IBW formulas.
What Is Ideal Body Weight?
Ideal Body Weight (IBW) formulas were developed primarily for medical and pharmacological use — specifically to calculate drug dosages, ventilator settings, and nutritional support requirements in clinical settings. They are height-based formulas that produce a single target weight number.
The most widely used IBW formula, developed by Dr. G.J. Hamwi in 1964, was originally created to estimate caloric needs in diabetic patients — not to define an aesthetic or athletic ideal. The Devine formula (1974) was created for drug dosing in anesthesia. Robinson (1983) and Miller (1983) were refinements that used additional population data.
All four formulas produce similar but not identical results. They're best understood as rough population-level estimates for sedentary, average-build adults — not personalized ideals for athletes or people with significant muscle mass.
The Formulas Explained
Hamwi (1964)
Male: 106 lbs + 6 lbs per inch over 5 ft
Female: 100 lbs + 5 lbs per inch over 5 ft
Devine (1974)
Male: 50 kg + 2.3 kg per inch over 5 ft → lbs
Female: 45.5 kg + 2.3 kg per inch over 5 ft → lbs
Robinson (1983)
Male: 52 kg + 1.9 kg per inch over 5 ft → lbs
Female: 49 kg + 1.7 kg per inch over 5 ft → lbs
Miller (1983)
Male: 56.2 kg + 1.41 kg per inch over 5 ft → lbs
Female: 53.1 kg + 1.36 kg per inch over 5 ft → lbs
Why IBW Is a Poor Metric for Trained Athletes
Muscle vs. Fat — Same Weight, Very Different Health
IBW formulas have no way to distinguish between a muscular athlete and an obese sedentary person of the same height. A 5'10" male competitive powerlifter at 220 lbs with 12% body fat is in exceptional health, yet every IBW formula would classify him as significantly "overweight." These formulas were never designed for people who resistance train.
Better Alternatives for Gym-Goers
For athletes and gym-goers, body composition goals are far more meaningful than scale weight targets. Setting a target body fat percentage (e.g., "I want to reach 12% body fat") combined with a lean body mass goal gives a complete picture of your ideal physique. Use the Body Fat Calculator and Lean Body Mass Calculator together for this purpose.
How to Set Realistic Body Composition Goals
Rather than targeting a specific scale weight, set goals around two numbers: (1) your target body fat percentage, and (2) your target lean body mass. For example: "I want to be 175 lbs at 12% body fat" gives you 154 lbs of LBM as your target — a measurable, achievable goal based on body composition rather than an arbitrary weight on a scale.
The combination of body fat percentage and lean body mass goals also tells you whether you need to bulk (increase LBM), cut (reduce fat mass while preserving LBM), or recompose (reduce fat while simultaneously building LBM). This framework is infinitely more useful than any IBW formula for active people.
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Frequently Asked Questions
Research comparing the four main IBW formulas suggests none is definitively superior for all populations. A 2016 analysis found that IBW formulas consistently underestimate actual healthy body weights for taller individuals. The Devine formula remains the most widely used in clinical settings (particularly for drug dosing), but the Robinson formula tends to align most closely with population-level health data. For practical fitness purposes, using the average of all four formulas — as this calculator does — provides a more balanced estimate than any single formula.
Only if you are sedentary and simply want a rough health benchmark. For anyone who trains regularly, IBW is a meaningless target — it ignores muscle mass entirely. A better goal framework for gym-goers is: identify your current body fat percentage, set a target body fat percentage, and calculate the implied goal weight at that body fat level using your current lean body mass as the baseline. This gives you a personalized, physique-based target rather than a statistical average.
Each formula was developed using different population samples, different statistical methods, and different intended clinical applications. The Hamwi formula uses round numbers and was designed for easy mental calculation. The metric-based formulas (Devine, Robinson, Miller) were developed from regression analyses of actual patient data. Because they used different datasets and regression approaches, they produce slightly different estimates. The differences are typically small (within 5-15 lbs) for average heights, but diverge more at very tall or very short statures.
All four IBW formulas use 5 feet as their baseline height and add weight for each inch above 5 feet. For individuals shorter than 5 feet, the formulas are typically modified to subtract weight for each inch below 5 feet (using the same per-inch increment). However, IBW formulas are generally considered least reliable for very short or very tall individuals — the linear relationship between height and ideal weight breaks down at the extremes of the height distribution.
Not exactly. IBW formulas produce a single point estimate, while BMI healthy weight corresponds to a range (BMI 18.5-24.9). For most heights, the IBW estimate falls roughly in the middle of the BMI healthy weight range, but they don't align precisely. The BMI "normal weight" range for a 5'10" male is 129-174 lbs, while IBW formulas typically suggest 160-170 lbs for the same height — inside the range but toward the upper end. Both metrics share the same fundamental flaw: neither accounts for body composition or muscle mass.