Which IBW formula is most accurate?

No single formula is definitively most accurate for all individuals, which is why multiple formulas are presented. Devine (1974) is most commonly used in clinical pharmacy. Robinson (1983) and Miller (1983) tend to produce slightly higher values, particularly for women. All formulas have limitations, especially for very tall individuals, athletes, and older adults who have lost lean mass.

Is ideal body weight the same as healthy body weight?

Not exactly. The BMI-based healthy weight range (BMI 18.5 to 24.9) is wider than most IBW formula results. IBW formulas often target the lower-middle of the BMI healthy range. A person at the upper end of the healthy BMI range may be above their IBW but still clinically healthy, particularly if they have above-average muscle mass.

How is ideal body weight used in clinical settings?

In clinical practice, IBW is used primarily for pharmacological dosing (aminoglycosides, vancomycin, some chemotherapy agents), calculating tidal volumes in mechanical ventilation, and estimating caloric needs in critically ill patients. It is not typically used as a weight loss target in outpatient settings, where BMI and body composition metrics are preferred.

Does ideal body weight account for age?

Standard IBW formulas do not adjust for age. Older adults naturally lose lean mass and bone density over time, meaning they may have lower actual lean body mass than the formulas predict. Some clinicians use adjusted IBW values for elderly patients. For older adults concerned about weight targets, working with a physician or registered dietitian is recommended.

Healthcare & Clinical

Ideal Body Weight Calculator

Calculate ideal body weight using the Devine, Robinson, Miller, and Hamwi formulas plus adjusted body weight for medication dosing.

MEDICAL DISCLAIMER

This calculator is for educational and clinical reference purposes only. Ideal body weight formulas were originally developed for drug dosing, ventilator settings, and nutritional assessments, not as standalone health indicators. Results must be interpreted by a qualified healthcare professional in the context of the patient's overall clinical picture. Do not use IBW alone to assess health status.

Biological Sex

Height

Actual Weight (for Adjusted BW)

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Introduction

"Ideal body weight" is a clinical term with a specific history. The formulas most calculators use, Devine (1974) for men and women, Robinson (1983), and Miller (1983), were originally developed not for fitness goals but for pharmacological dosing, to determine drug doses based on lean body mass rather than actual weight. The National Institutes of Health uses BMI-based ranges for population health guidance, while clinical pharmacy still relies on Devine's formula for medication calculations. None of these formulas were designed for aesthetic targets. This calculator computes ideal body weight using four validated formulas, displays the range rather than a single number, contextualizes the result against BMI-based healthy weight range for your height, and explains what "ideal" means in clinical versus fitness contexts. Knowing the distinction prevents both under- and over-correction when setting weight goals.

What This Calculator Does

This ideal body weight calculator computes IBW using four established formulas (Devine, Robinson, Miller, and Hamwi) for adults, shows the range across all four formulas, and compares the result to the BMI-based healthy weight range for your height. Enter sex, height, and current weight to receive IBW estimates, the percentage difference between current and ideal weight, and a clinical versus fitness context interpretation. The calculator supports both imperial and metric units.

The Formula

Devine (Male): IBW = 50 + 2.3 x (height_inches - 60) | Devine (Female): IBW = 45.5 + 2.3 x (height_inches - 60) | Robinson (Male): IBW = 52 + 1.9 x (height_inches - 60) | Hamwi (Male): IBW = 48 + 2.7 x (height_inches - 60)

All IBW formulas start from a base weight at 5 feet (60 inches) and add a fixed amount per additional inch of height. Devine (1974) is the most widely cited in clinical settings, particularly for pharmacological dosing. Robinson (1983) and Miller (1983) were developed by analyzing US Metropolitan Life Insurance tables and NHANES data. Hamwi (1964) is still referenced in some clinical nutrition contexts. The formulas produce different results for the same individual, which is why presenting a range rather than a single number is more accurate.

Step-by-Step Example

Enter sex and height

Female, height 5'6" (66 inches). The formula adds weight increments per inch above 60 inches (6 extra inches above the 5'0" base).

Calculate IBW using each formula

Devine: 45.5 + (2.3 x 6) = 45.5 + 13.8 = 59.3 kg = 130.7 lbs. Robinson: 49 + (1.7 x 6) = 59.2 kg = 130.5 lbs. Miller: 53.1 + (1.36 x 6) = 61.3 kg = 135.1 lbs. Hamwi: 45.4 + (2.27 x 6) = 59.0 kg = 130.1 lbs.

Compare to BMI-based healthy range

For 5'6", BMI 18.5 to 24.9 corresponds to 115 to 154 lbs. The IBW range of 130 to 135 lbs falls near the lower-middle of the healthy BMI range. Current weight: 148 lbs is within the BMI healthy range but 13 to 18 lbs above IBW formulas.

Contextualize the result

A current weight of 148 lbs at 5'6" is clinically healthy (BMI 23.9). The IBW formulas suggest a slightly lighter frame but were developed for average body compositions. If body fat is under 28%, the current weight may be more appropriate than the formula target.

Real-World Use Cases

Clinical Pharmacology Dosing

A pharmacist calculates IBW for a 5'10" male patient weighing 240 lbs to determine the correct aminoglycoside antibiotic dose. IBW (Devine): 50 + (2.3 x 10) = 73 kg = 160.9 lbs. The drug is dosed on IBW of 73 kg, not actual weight of 109 kg, because the medication distributes into lean tissue, not adipose tissue.

Goal Weight Setting for a Weight Loss Program

A registered dietitian uses IBW as one reference point when discussing goal weight with a client. The client (female, 5'4", 185 lbs) has an IBW range of 120 to 128 lbs. Rather than using IBW as a fixed target, the dietitian sets an initial goal of 155 lbs (in the upper BMI healthy range), acknowledging that IBW formulas do not account for the client's muscular build.

Occupational Health BMI Screening

A corporate wellness coordinator uses IBW as a reference alongside BMI for a worksite health screening program. Employees above 130% of IBW are flagged for optional follow-up with a dietitian. This approach catches metabolic risk in individuals who may be within the BMI overweight range but whose specific height-weight ratio indicates greater deviation from estimated lean body mass norms.

Comparison

Height	Devine IBW (Female)	BMI Healthy Range	Devine IBW (Male)	BMI Healthy Range
5'2" (62")	121.8 lbs	101-136 lbs	109.2 lbs	104-140 lbs
5'4" (64")	126.4 lbs	108-145 lbs	113.8 lbs	111-149 lbs
5'6" (66")	130.9 lbs	115-154 lbs	118.4 lbs	118-159 lbs
5'8" (68")	135.5 lbs	122-164 lbs	123.0 lbs	125-168 lbs
5'10" (70")	140.1 lbs	129-174 lbs	127.6 lbs	132-179 lbs

Common Mistakes to Avoid

Using a single IBW formula result as a fixed target weight. The four major formulas produce results ranging from 5 to 15 lbs apart for the same individual. A range is more honest than a single number, and neither the range nor any formula accounts for individual body composition.
Applying IBW to individuals under 5 feet tall or children. All major IBW formulas assume adult stature and break down for heights below 5 feet. For pediatric patients, use age- and sex-specific growth charts from the CDC.
Treating IBW as synonymous with goal weight for fitness. IBW formulas were developed for pharmacological dosing and statistical analysis, not for personal fitness planning. A trained athlete may be well above their IBW at a very low body fat percentage.
Confusing IBW with adjusted body weight (AdjBW). For patients who are more than 30% above IBW, pharmacists and dietitians use adjusted body weight: AdjBW = IBW + 0.4 x (Actual - IBW). This is a distinct clinical calculation from standard IBW.

Frequently Asked Questions

Accuracy and Disclaimer

This calculator provides ideal body weight estimates based on established clinical formulas for reference purposes only. IBW formulas do not account for individual body composition, fitness level, age-related changes, or medical conditions. These results are not a target weight recommendation or a medical diagnosis. Consult a qualified healthcare provider or registered dietitian before setting weight goals or beginning a weight management program.

Conclusion

Ideal body weight formulas are tools for clinical estimation, not personal fitness mandates. A 5'8" woman whose IBW range is 130 to 140 lbs may be perfectly healthy at 155 lbs if her body fat is 22% and she is physically active. Use IBW alongside the Body Fat Calculator for a more complete picture, and the Calorie Needs Calculator to plan the caloric approach if you are working toward a specific weight target.

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