Ideal Body Weight Analysis
Medical standards for healthy physiological weight.
Clinical IBW Engine
Ideal Weight Calculator
Calculate your ideal body weight using five clinically validated formulas Devine, Robinson, Miller, Hamwi, and the 2016 Peterson equation with your height, sex, and body frame size.
ZA
Reviewed by Dr. Zohaib Ali
Last updated April 2026
What is ideal body weight (IBW)?
Quick Answer: Ideal body weight (IBW) is a clinical estimate of an appropriate weight for a given height and sex, calculated using one of several validated formulas.
The most widely used in US clinical settings is the Devine formula: for men, IBW = 50 kg + 2.3 kg per inch over 5 feet; for women, IBW = 45.5 kg + 2.3 kg per inch over 5 feet.
IBW was originally developed for medication dosing, not fitness goals. A healthy weight range rather than a single ideal number is more clinically meaningful for most individuals and corresponds to a BMI of 18.5 to 24.9 at your height.
Source: Devine BJ, Drug Intelligence and Clinical Pharmacy, 1974; WHO BMI Classification.
This calculator provides general hydration estimates. This is not medical advice. Consult a healthcare provider for medical conditions affecting fluid balance, including kidney disease, heart conditions, or diuretic medications.
Clinical Formulas: Devine; Hamwi; Robinson; Miller; Peterson (2016).
The Story Behind Ideal Body Weight: It Started in a Pharmacy
Here is the piece of context every ideal weight calculator omits: the concept of ideal body weight was not invented by a fitness professional or a nutritionist. It was created by a pharmacist.
In 1974, Dr. B.J. Devine published a paper in Drug Intelligence and Clinical Pharmacy with a straightforward clinical problem: certain medications need to be dosed based on body weight, but for obese patients, using actual body weight produces dangerously high doses. The body does not distribute fat-soluble drugs the same way it distributes them through lean tissue. Devine needed a formula that estimated the weight of lean body mass, the part of a person's body that actually matters for drug distribution.
The Devine formula he published became the standard tool in US hospital pharmacies. It's used today when a pharmacist doses digoxin for heart rhythm, gentamicin for bacterial infection, vancomycin for MRSA, and dozens of other drugs where dosing by actual weight in obese patients would cause toxicity.
The reason this matters for you: the Devine formula gives you an IBW estimate, not a fitness prescription. The number it produces is not a goal to hit. It's a clinical reference point, a way to understand where you sit relative to the weight range associated with lowest disease risk. This distinction is the most important thing to understand before reading your result.
The Five IBW Formulas: What Each One Is and Why They Differ
Five main formulas are used to calculate ideal body weight in US clinical and research settings. They were developed in different decades for different purposes which explains why they don't always agree.
Devine Formula (1974): Most widely used in clinical settings
Men: IBW = 50 kg + 2.3 kg × (height in inches − 60)
Women: IBW = 45.5 kg + 2.3 kg × (height in inches − 60)
The original. Used in hospital pharmacy for drug dosing. Considered the most clinically validated formula and the standard reference in US medical settings.
Hamwi Formula (1964): The original dietitian's formula
Men: IBW = 106 lb + 6 lb × (height in inches − 60)
Women: IBW = 100 lb + 5 lb × (height in inches − 60)
Developed by Dr. George Hamwi for clinical nutrition assessment. Predates Devine and is still widely taught in US dietitian training programs. The 5 lb and 6 lb per inch increments are approximate and produce slightly higher estimates than Devine for tall individuals.
Robinson Formula (1983):
Men: IBW = 52 kg + 1.9 kg × (h − 60)
Women: IBW = 49 kg + 1.7 kg × (h − 60)
A refinement of Devine, using a smaller increment per inch above 5 feet. Produces lower IBW estimates for very tall individuals where Devine may overestimate lean mass.
Miller Formula (1983):
Men: IBW = 56.2 kg + 1.41 kg × (h − 60)
Women: IBW = 53.1 kg + 1.36 kg × (h − 60)
Published simultaneously with Robinson as an alternative refinement. Tends to produce the highest estimates of the four older formulas for shorter individuals.
Peterson Equation (2016): The most recent formula
IBW = 2.2 × BMI + 3.5 × BMI × (height in meters − 1.5)
Published in the American Journal of Clinical Nutrition by Peterson et al. in 2016, this formula is the most significant advance in IBW calculation in decades. It acknowledgment that ideal weight is not determined by height and sex alone but by a target body composition.
Why the formulas give different numbers:All five formulas use height as the primary variable and were developed from different populations and with different purposes. For a 5'8" man, results typically range from 154 lbs (Devine) to 164 lbs (Miller) , a 10-pound spread from four formulas that all claim to measure the same thing. This range is one reason the ACSM and major clinical guidelines emphasize using a healthy weight range rather than a single ideal number.
Body Frame Size: How to Measure It Accurately
Most ideal weight calculators ask you to select your frame size small, medium, or large without telling you how to determine it. Frame size affects IBW by approximately 10% in either direction: small-framed individuals subtract approximately 10%, large-framed individuals add approximately 10%.
There are two validated methods for measuring frame size:
Method 1: Wrist circumference
Measure the circumference of your wrist at the smallest point, just below the wrist bone. Use a flexible tape measure.
Method 2: Elbow breadth
Extend your arm forward with your palm facing upward. Bend your elbow to 90 degrees. Measure the distance across the two prominent bones of your elbow.
| Height (Women) | Small Frame | Medium Frame | Large Frame |
|---|---|---|---|
| Under 5'2" | Wrist < 5.5" | 5.5" – 5.75" | > 5.75" |
| 5'2" – 5'5" | Wrist < 6" | 6" – 6.25" | > 6.25" |
| Over 5'5" | Wrist < 6.25" | 6.25" – 6.5" | > 6.5" |
For men of all heights: small frame = wrist under 6.5"; medium frame = 6.5"–7.5"; large frame = over 7.5".
Adjusted Body Weight: The Clinical Calculation You've Never Heard Of
When a patient's actual body weight significantly exceeds their IBW typically when actual weight is more than 30% above IBW clinicians use Adjusted Body Weight (AjBW) rather than either actual weight or IBW alone.
Formula: AjBW = IBW + 0.25 × (Actual Weight − IBW)
Example: A patient weighs 250 lbs with an IBW of 160 lbs. AjBW = 160 + 0.25 × (250 − 160) = 160 + 22.5 = 182.5 lbs
This adjusted figure is used in several important clinical contexts in the United States:
Drug dosing. For certain drugs in obese patients, AjBW produces a more appropriate dose estimate than either IBW or actual weight particularly for hydrophilic drugs that partially distribute into adipose tissue.
ICU nutritional support. The 2016 ASPEN/SCCM Critical Care Nutrition Guidelines recommend using AjBW for calculating caloric targets in critically ill obese patients.
Bariatric surgery evaluation. Clinicians use IBW to calculate percent excess body weight as a surgery outcome metric: Excess Weight = Actual Weight − IBW.
Sources: ASPEN/SCCM Critical Care Nutrition Guidelines 2016; Hallynck TH et al., Clinical Pharmacokinetics, 1981
IBW Is a Starting Point Not a Verdict:
The most important thing to say about your ideal body weight result is what it is not: it is not a diagnosis, a mandate, or a definition of your health.
IBW formulas were developed from population studies and actuarial insurance data. They produce an estimate of the weight range associated with lowest statistical disease risk at a given height but they do not account for muscle mass, bone density, age-related body composition changes, or individual metabolic variation.
A 45-year-old man who has strength-trained for 20 years may weigh 30 lbs above his Devine IBW and have a body fat percentage of 12% far healthier by any body composition measure than someone at exactly their IBW with 28% body fat.
What to use instead of a single IBW number: The ACSM's 2026 position stand recommends using IBW alongside body composition analysis rather than as a standalone metric. A healthy weight range—the weight corresponding to a BMI of 18.5 to 24.9 at your height—is a more appropriate personal target for most individuals.
Ideal Weight vs Healthy Weight Range: The Table Every Calculator Needs
| Height | Healthy Weight Range (BMI 18.5–24.9) | Devine IBW (Men) | Devine IBW (Women) |
|---|---|---|---|
| 5'0" | 97 – 130 lbs | 110 lbs | 100 lbs |
| 5'1" | 100 – 135 lbs | 115 lbs | 105 lbs |
| 5'2" | 104 – 140 lbs | 120 lbs | 110 lbs |
| 5'3" | 107 – 145 lbs | 125 lbs | 115 lbs |
| 5'4" | 111 – 150 lbs | 130 lbs | 120 lbs |
| 5'5" | 115 – 155 lbs | 135 lbs | 125 lbs |
| 5'6" | 118 – 160 lbs | 140 lbs | 130 lbs |
| 5'7" | 122 – 164 lbs | 145 lbs | 135 lbs |
| 5'8" | 126 – 169 lbs | 150 lbs | 140 lbs |
| 5'9" | 129 – 175 lbs | 155 lbs | 145 lbs |
| 5'10" | 133 – 179 lbs | 160 lbs | 150 lbs |
| 5'11" | 137 – 185 lbs | 165 lbs | 155 lbs |
| 6'0" | 141 – 190 lbs | 170 lbs | 160 lbs |
| 6'1" | 145 – 195 lbs | 175 lbs | 165 lbs |
| 6'2" | 149 – 200 lbs | 180 lbs | 170 lbs |
| 6'3" | 153 – 206 lbs | 185 lbs | 175 lbs |
Healthy weight ranges from WHO BMI Classification (18.5–24.9). Devine IBW rounded to the nearest 5 lbs for practical reference. Individual healthy weight depends on muscle mass, age, bone density, and clinical assessment.
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