Ideal Weight Calculator

Ideal body weight formulas were not developed as fitness goals. They originated in clinical settings to estimate drug dosing, adjust ventilator settings, and compare populations. The Hamwi formula dates to 1964 and was designed for insulin calculations. Devine followed in 1974 for gentamicin dosing. Robinson and Miller refined the numbers in subsequent decades using broader data sets. Because each formula uses slightly different base weights and per-inch multipliers, they produce a spread rather than a single number. That spread is actually more useful than any one figure. If you fall within the range, all four formulas broadly agree you are near a typical weight for your height. If you are outside it, the gap is worth discussing with a clinician. This calculator shows all four formulas and their average. The results are in kilograms and reflect height converted from centimeters to inches, since all four formulas were originally written in imperial units.

• Setting a weight-loss reference point: If you are starting a weight-loss program, the ideal weight range gives you a rough target to discuss with your doctor or dietitian. It is more informative than a single number because it shows the spread across four established formulas.
• Understanding clinical dosing references: Pharmacists and anesthesiologists use ideal body weight to calculate drug doses for medications where actual body weight would overdose a larger person. Knowing your IBW helps you ask informed questions about dosing decisions.
• Tracking progress in a fitness program: Rather than chasing a specific number on a scale, you can use the IBW range as a broad zone to work toward. Reaching any point within the range is a meaningful milestone regardless of which formula you favor.
• Comparing BMI to formula-based estimates: BMI and ideal weight formulas sometimes point to different conclusions for short or tall people. Checking both helps you see whether the two approaches agree or diverge for your specific height.

• Treating ideal weight as a medical prescription: These formulas are statistical references derived from population averages. A person with a large bone structure or significant muscle mass may be healthy at a weight above all four formula estimates.
• Ignoring the spread between formulas: The four formulas can differ by 3 to 6 kg for the same height. Using only one formula gives a false sense of precision. The range is the more honest output.
• Applying the result to children or teens: All four formulas were derived from adult populations. They are not valid for people under 18, for whom pediatric growth charts and age-adjusted BMI are the appropriate references.
• Confusing height input units: This calculator takes height in centimeters. If you enter your height in feet and inches by mistake, the result will be far off. Double-check the unit before reading the output.

1. 1Enter your height in centimeters. The calculator converts it to inches internally.
2. 2Select your sex. Each formula has separate male and female coefficients.
3. 3The calculator finds how many inches your height exceeds five feet (60 inches). Heights below five feet use zero for this value.
4. 4It applies each formula: a sex-specific base weight plus a per-inch multiplier times the inches over 60.
5. 5The four results are displayed individually and averaged to show a reference range.
6. 6A note reminds you these are statistical guidelines derived from population studies, not targets prescribed by a doctor.

• Use the range, not the average: The average of four formulas is a useful single number, but the full range (minimum to maximum) tells you more. If your goal weight falls anywhere in the range, all major references broadly agree.
• Pair with body fat percentage for a fuller picture: Two people at the same ideal weight can have very different body compositions. A body fat percentage measurement (via DEXA, hydrostatic weighing, or a reasonable skinfold estimate) adds meaningful context.
• Revisit after major muscle gain or loss: IBW formulas do not adjust for muscle mass. If you have been strength training consistently for a year, your ideal weight in a functional sense may be above the formula range, which was built on general population data.
• Use for medication conversations, not just fitness: If you are ever prescribed a weight-based medication, knowing your IBW helps you have a more informed conversation with your pharmacist about whether dosing is based on actual, ideal, or adjusted body weight.