Adjusted Body Weight Calculator

Calculate Adjusted Body Weight (AdjBW) for patients who are obese or overweight. Enter your sex, actual body weight, and height — and get back your Ideal Body Weight (IBW), Adjusted Body Weight, and BMI. Used clinically to estimate active lean body tissue for more accurate nutritional and medication dosing.

Disclaimer: This tool is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making any health-related decisions.

Sex *

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Enter current body weight in kilograms

Results

Adjusted Body Weight (AdjBW)

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Ideal Body Weight (IBW)

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BMI

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BMI Category

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% Over IBW

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Frequently Asked Questions

What is Adjusted Body Weight (AdjBW)?

Adjusted Body Weight is a calculated weight used in clinical settings for obese patients to better estimate their active lean body tissue. It accounts for the fact that adipose tissue is not as metabolically active as lean tissue, so using actual body weight alone can overestimate nutritional and medication needs. AdjBW is typically used when actual body weight exceeds ideal body weight by more than 20–30%.

How is Adjusted Body Weight calculated?

AdjBW is calculated using the formula: AdjBW = IBW + 0.4 × (Actual Body Weight − IBW). The Ideal Body Weight (IBW) is first determined using the Devine formula: IBW (males) = 50 kg + 2.3 kg per inch over 5 feet; IBW (females) = 45.5 kg + 2.3 kg per inch over 5 feet.

When should Adjusted Body Weight be used instead of Ideal Body Weight?

AdjBW is used when a patient's actual body weight is more than 120–130% of their IBW (i.e., they are obese). For patients at or below this threshold, IBW or actual body weight may be more appropriate depending on the clinical context. Always consult clinical guidelines for your specific application.

What is the correction factor of 0.4 in the AdjBW formula?

The 0.4 correction factor represents an estimate that approximately 40% of excess body weight above IBW in obese patients consists of metabolically active lean tissue. This factor is widely accepted in clinical nutrition but may vary between institutions — some use 0.25 for certain drug dosing calculations.

What is Ideal Body Weight (IBW) and how is it different from AdjBW?

IBW is an estimate of a healthy body weight based on height and sex, calculated using the Devine formula. AdjBW is a modification of IBW that accounts for a portion of excess weight in obese patients. IBW is used for normal-weight patients, while AdjBW is preferred for those who are significantly overweight or obese.

Can this calculator be used for all patients?

This calculator is intended for adults. It is most relevant for patients whose actual body weight exceeds their IBW by more than 20–30%. It is not validated for pediatric patients, pregnant women, or patients with conditions causing abnormal fluid retention (e.g., ascites, edema). Clinical judgment should always be applied.

What clinical applications use Adjusted Body Weight?

AdjBW is commonly used in clinical nutrition to estimate caloric and protein requirements for obese patients, and in pharmacy for weight-based dosing of medications such as aminoglycosides, heparin, and certain chemotherapy agents. It is also used in critical care and renal dietetics.

What BMI is considered obese, and does it affect which weight to use?

A BMI of 30 or above is classified as obese. When a patient's BMI falls in the obese range and their actual weight significantly exceeds their IBW, AdjBW is generally the recommended weight to use for nutritional calculations. For overweight patients (BMI 25–29.9), clinical protocols may vary — some use actual body weight, others use IBW or AdjBW.