Ideal Body Weight Calculator (Devine Formula)

Enter your height and sex to calculate your ideal body weight using the Devine formula, plus a Hamwi cross-reference and healthy weight range.

Created by Luis GonzalezLast updated: May 9, 2026

How to Use This Calculator

1
Enter Patient Height
Input the patient's height in inches (e.g., 68 for 5ft 8in). The Devine formula is based on height above 5 feet.
2
Select Patient Sex
Choose 'Male' or 'Female' to apply the appropriate Devine formula, as baseline weights differ between sexes.
3
Review Medical IBW Results
Examine the calculated Ideal Body Weight in kilograms and pounds, the healthy weight range, and a comparison to the Hamwi formula for clinical context.

Example Calculation

A clinician needs to quickly determine the ideal body weight for a male patient who is 5ft 8in tall for medication dosing.

Height

68 in

Sex

Male

Results

68.4 kg

Tips

Use IBW for Hydrophilic Drug Dosing

For hydrophilic (water-soluble) medications, using IBW for dosing helps prevent accumulation and toxicity in obese patients, as these drugs primarily distribute in lean body mass. Always verify specific drug guidelines.

Consider Adjusted Body Weight (ABW)

For some medications in obese patients, neither actual weight nor IBW is ideal. An Adjusted Body Weight (ABW) (IBW + 0.4 * (actual weight - IBW)) may be used. Consult pharmacy resources for drug-specific recommendations.

Educate Patients on Healthy Ranges

When discussing ideal body weight with patients, emphasize the healthy weight range (IBW ± 10%) rather than a single number. This provides a more realistic and achievable target, acknowledging individual physiological variations.

Precision in Care: The Devine Ideal Body Weight Medical Calculator

The Devine Ideal Body Weight Medical Calculator is a critical tool for healthcare professionals, providing a precise estimate of Ideal Body Weight (IBW) based on patient height and sex. This calculation is indispensable for accurate medication dosing, ventilator settings, and nutritional assessments. In clinical practice, where patient safety and therapeutic efficacy are paramount, reliance on standardized formulas like Devine's helps prevent errors that could arise from using actual body weight alone, especially in cases of obesity or severe underweight.

Clinical Utility of Ideal Body Weight in Medical Decision-Making

The Devine formula, developed in 1974, is a cornerstone in hospital and clinic settings due to its practical applications. It's crucial for calculating dosages for medications such as antibiotics, chemotherapy agents, and anesthetic drugs, where precise body mass estimation is critical for patient safety. IBW also helps clinicians differentiate between true fluid overload and simply being overweight, guiding appropriate diuretic therapy. Furthermore, it's used in nutritional assessments for patients requiring parenteral or enteral feeding, ensuring optimal caloric and protein delivery. Always consult a licensed healthcare professional for all medical decisions, as these calculations are tools to aid expert judgment.

The Devine Formula for Clinical Ideal Body Weight

The Devine formula, a widely accepted standard in clinical pharmacology, calculates Ideal Body Weight (IBW) based on a patient's height and sex. It posits a base weight for a 5-foot individual and adds a specific increment for each additional inch.

For Males:

IBW (kg) = 50 + 2.3 × (height in inches - 60)

For Females:

IBW (kg) = 45.5 + 2.3 × (height in inches - 60)

The result is IBW in kilograms, which can then be converted to pounds. This formula's consistent application aids in standardizing medical treatments across diverse patient populations.

💡 Accurate patient parameters, including IBW, are essential for safe medical interventions. Our Safe Dose Range Checker Calculator can help verify medication dosages based on these critical values.

Determining IBW for a 5ft 8in Male Patient

Consider a male patient standing 5 feet 8 inches tall, for whom a physician needs to determine the Ideal Body Weight for medication purposes:

Height: 68 inches
Sex: Male

Applying the Devine formula for males:

Inches above 5 feet = 68 - 60 = 8 inches
IBW (kg) = 50 + (2.3 × 8)
IBW (kg) = 50 + 18.4 = 68.4 kg

The Ideal Body Weight for this patient is 68.4 kg, which is approximately 150.8 lbs. The calculator also provides a healthy weight range of 61.6–75.2 kg (IBW ± 10%) and indicates that the Hamwi formula, an alternative reference, would estimate a very similar 71.7 kg, confirming the consistency across established methods.

💡 Beyond individual metrics, clinical scores provide rapid patient assessment. The Sepsis qSOFA Score Calculator is another tool that aids in quickly identifying critical conditions.

Clinical Utility of Ideal Body Weight in Medical Decision-Making

Reference Ranges for Ideal Body Weight Formulas

In medical practice, various ideal body weight (IBW) formulas, such as Devine's and Hamwi's, are used to estimate a healthy weight. These formulas, while similar, often yield slightly different results. For instance, for an adult male of 5'8" (68 inches), Devine's formula suggests an IBW of approximately 68.4 kg, whereas Hamwi's formula might estimate closer to 71.7 kg. These variations are generally considered within a clinically acceptable range, often defined as ±10% around a target weight. Organizations like the American Society for Parenteral and Enteral Nutrition (ASPEN) provide comprehensive guidelines on the appropriate use of IBW, actual body weight, and adjusted body weight in their nutrition support recommendations, often favoring IBW for specific drug calculations or nutritional assessments.

Frequently Asked Questions

What is the Devine formula for ideal body weight in a medical context?

The Devine formula is a standard clinical calculation for estimating ideal body weight (IBW), crucial for various medical decisions. For males, it's 50 kg + 2.3 kg per inch over 5 feet, and for females, it's 45.5 kg + 2.3 kg per inch over 5 feet. This formula helps clinicians standardize drug dosages and assess nutritional needs, particularly when actual body weight might be misleading, such as in obesity.

Why is IBW important for medication dosing?

Ideal body weight (IBW) is critical for medication dosing to ensure therapeutic efficacy and minimize adverse effects. Many drugs, especially those that are water-soluble or renally cleared, distribute primarily into lean body mass. Using actual weight in obese patients for such drugs can lead to overdosing, while underdosing can occur in underweight individuals if not properly adjusted. IBW provides a more accurate physiological reference.

How does IBW relate to ventilator settings?

In critical care, ideal body weight (IBW) is often used to calculate appropriate tidal volumes for mechanical ventilation. Lung size correlates better with a patient's height and ideal weight than with their actual body weight, especially in obese patients. Using IBW for ventilator settings helps prevent lung injury and optimize respiratory support, improving patient outcomes in intensive care units.

What is the difference between IBW and adjusted body weight (ABW)?

Ideal body weight (IBW) is a theoretical weight based on height and sex. Adjusted body weight (ABW) is a modified calculation used for some medications in obese patients to account for the additional fat mass without risking overdose. ABW typically uses a formula like: IBW + 0.4 × (actual body weight - IBW), creating a weight between IBW and actual weight that is more physiologically relevant for drug distribution.