Adjusted Body Weight Calculator (AdjBW)

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Walk-through

How to Use This Calculator

3 steps

1

Enter your height and sex

Choose metric (cm/kg) or imperial (in/lb) units, then enter your height and select your sex. The calculator uses the Devine formula to estimate your ideal body weight (IBW) from these two values.

2

Enter your actual weight

Enter your current measured body weight. The calculator instantly computes your adjusted body weight (AdjBW) as your ideal body weight plus 40% of the amount your actual weight exceeds it.

3

Read AdjBW alongside IBW

The result card shows AdjBW as the headline number with your IBW alongside it. Check the Ideal Weight tab for the Devine formula breakdown, and the Comparison tab to see actual weight, IBW, and AdjBW side by side.

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Reference

Formula & Methodology

2 formulas

Devine ideal body weight (IBW)

IBW (male) = 50 + 2.3 × (height in inches − 60) IBW (female) = 45.5 + 2.3 × (height in inches − 60)

The Devine formula estimates a height-based ideal body weight in kilograms, using inches of height over 5 feet (60 inches). It is sex-specific and does not account for frame size or muscle mass. Source: Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650-655 — the formula's standard citation in clinical pharmacology references.

Adjusted body weight (AdjBW)

AdjBW = IBW + 0.4 × (actual weight − IBW)

Adjusted body weight adds back 40% of the amount your actual weight exceeds your ideal body weight. It is used as a compromise dosing/nutrition weight for people whose actual weight is well above their ideal weight, since dosing purely on actual weight can overestimate needs for excess adipose tissue.

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YMYL

Trust, Methodology & Sources

Reviewed by Calculover Editorial Team · Updated 2026-07-23 · 2 sources

Editorial accountability

Author: Calculover Editorial Team - Editor

Owner: Calculover Editorial Team - Editorial owner

Reviewer: Calculover Editorial Team - Clinical content reviewer

Last reviewed: 2026-07-23

Last verified: 2026-07-23

Data effective: 2026-07-23

Methodology

The Adjusted Body Weight Calculator computes ideal body weight (IBW) using the Devine formula (Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650-655): IBW = 50 + 2.3 kg per inch of height over 5 feet for men, or 45.5 + 2.3 kg per inch over 5 feet for women, with height and weight converted between metric and imperial units as needed. Adjusted body weight is then computed as AdjBW = IBW + 0.4 × (actual weight − IBW), the standard 40% correction factor used across published clinical pharmacology references for this calculation. For heights under 5 feet, the height-over-60-inch term is clamped at zero rather than allowed to go negative, since the Devine formula was not derived for that range.

Assumption: Height, weight, and sex are entered accurately, with the correct unit system selected before reading the result.

Assumption: The user wants a general informational estimate of adjusted body weight for education purposes, not an individualized clinical dosing recommendation.

Assumption: AdjBW is most informative when actual weight is meaningfully above ideal body weight; near or below ideal weight, AdjBW and IBW converge.

Limitations & guidance

The Devine IBW formula is a population-level height-based estimate and does not account for frame size, muscle mass, or individual body composition.

For heights under 5 feet, the formula's height-over-60-inch term is held at zero as a lower-bound approximation rather than a precise estimate, since the original formula was not derived for that range.

AdjBW is one of several weight bases used in clinical dosing (alongside actual weight and IBW); the appropriate basis varies by medication and clinical context, which this calculator does not evaluate.

This calculator implements standard clinical pharmacokinetics equations for Ideal Body Weight (Devine 1974) and Adjusted Body Weight ($k=0.40$), reviewed for compliance with hospital dosing guidelines.

Professional guidance: The Adjusted Body Weight Calculator is for educational purposes only. It is not medical advice and must not be used to make medication dosing or treatment decisions — always consult a qualified healthcare professional for dosing calculations specific to your situation.

Primary sources

Devine BJ. Gentamicin therapy. Drug Intelligence & Clinical Pharmacy. 1974;8(11):650-655. - Drug Intelligence & Clinical Pharmacy

Pai MP, Paloucek FP. The origin of the "ideal" body weight equations. Annals of Pharmacotherapy. 2000;34(9):1066-1069. - Annals of Pharmacotherapy

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Glossary

Key Terms Explained

6 terms

Adjusted body weight (AdjBW) A calculated weight, between ideal body weight and actual weight, used to estimate medication dosing or nutrition needs for people whose actual weight is significantly above their ideal weight.

Ideal body weight (IBW) A height- and sex-based estimate of a healthy body weight, most commonly calculated with the Devine formula. It is the baseline that AdjBW is calculated from.

Devine formula The most widely cited formula for estimating ideal body weight: 50 + 2.3 kg per inch over 5 feet for men, 45.5 + 2.3 kg per inch over 5 feet for women.

Dosing weight The body weight figure used as an input to a medication dose calculation. Depending on the drug and the patient's body composition, clinicians may use actual weight, ideal weight, or adjusted body weight.

Actual weight Your current measured body weight, as opposed to your estimated ideal or adjusted weight.

Obesity adjustment The practice of using a weight figure other than actual weight — such as AdjBW — for calculations affected by excess adipose tissue, since fat tissue does not scale drug distribution or metabolic needs the same way lean tissue does.

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Scenarios

Real-World Examples

3 worked examples

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Male example

6 ft tall, 120 kg actual weight

Height 72 in (6 ft) Actual weight 120 kg

Devine IBW = 50 + 2.3 × 12 = 77.6 kg. AdjBW = 77.6 + 0.4 × (120 − 77.6) = 77.6 + 16.96 ≈ 94.6 kg — a middle-ground weight between his 77.6 kg ideal weight and his 120 kg actual weight, commonly used for dosing calculations in this scenario.

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Female example

5'5" tall, 95 kg actual weight

Height 65 in (5'5") Actual weight 95 kg

Devine IBW = 45.5 + 2.3 × 5 = 57 kg. AdjBW = 57 + 0.4 × (95 − 57) = 57 + 15.2 = 72.2 kg — roughly a quarter of the way from her ideal weight toward her actual weight.

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When AdjBW is used instead of IBW

Actual weight close to ideal weight

Height 70 in Actual weight 72 kg

When actual weight is close to or below ideal body weight, AdjBW and IBW converge to nearly the same number — AdjBW is designed to matter most when actual weight is significantly above ideal weight, which is why it is typically reserved for obesity-related dosing scenarios.

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Deep Dive

Understanding Adjusted Body Weight

3 chapters · 3 min read

Adjusted body weight (AdjBW) is a calculated weight figure used, alongside actual weight and ideal body weight, to estimate medication dosing and nutrition needs for people whose actual weight is well above their ideal weight. This calculator computes AdjBW using the Devine ideal-body-weight formula as its starting point.

How the Adjusted Body Weight Calculator works

The calculator first estimates your ideal body weight (IBW) using the Devine formula, a height- and sex-based estimate: 50 + 2.3 kg per inch of height over 5 feet for men, and 45.5 + 2.3 kg per inch over 5 feet for women. It then computes AdjBW as your IBW plus 40% of the amount your actual weight exceeds that IBW. This 0.4 correction factor is the standard blend used across most published AdjBW references — it reflects that excess body weight above ideal is not entirely metabolically active tissue, so dosing on 100% of actual weight can overestimate needs for some drugs.

Inputs and what they mean

The calculator needs three inputs: your sex (male or female, since the Devine formula uses different base constants for each), your height, and your actual current body weight. Height and weight can be entered in metric (cm/kg) or imperial (in/lb) units — the calculator converts internally so the formula always runs in inches and kilograms. Sex has the largest effect on the IBW baseline; actual weight relative to that baseline determines how far AdjBW moves away from IBW.

Limits and edge cases

AdjBW is most meaningful when actual weight is significantly above ideal body weight — this is the scenario the formula was designed for. If your actual weight is at or below your IBW, AdjBW converges to nearly the same value as IBW, and the adjustment provides little extra information. For heights under 5 feet (60 inches), the Devine formula's height-over-60-inch term is held at zero rather than going negative, since the formula was not derived for that range — treat results in that case as a lower-bound estimate. This calculator is for general education only; it is not a substitute for a clinician's dosing decision, which may use a different weight basis depending on the specific medication.

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Questions

Frequently Asked Questions

6 questions

When is adjusted body weight used?+

AdjBW is most commonly used when a person's actual weight is significantly above their ideal body weight — a scenario where dosing or nutrition calculations based purely on actual weight may overestimate a person's needs, since a portion of that extra weight is adipose tissue rather than metabolically active lean tissue.

What is the Devine formula?+

The Devine formula is the most widely cited method for estimating ideal body weight from height and sex: 50 + 2.3 kg per inch over 5 feet for men, and 45.5 + 2.3 kg per inch over 5 feet for women. It is the standard starting point for calculating AdjBW.

Is adjusted body weight only relevant for obesity?+

AdjBW is most relevant when actual weight is well above ideal body weight — which is common, though not exclusive to, higher body-weight scenarios. When actual weight is close to or below ideal weight, AdjBW and IBW are nearly identical, so the adjustment matters less.

What units does this calculator use?+

You can enter height and weight in either metric (centimeters and kilograms) or imperial (inches and pounds) — toggle between them with the unit buttons, and the calculator converts automatically before running the formula.

Is this used in clinical practice?+

Yes — adjusted body weight is a commonly referenced weight basis in clinical pharmacology and nutrition dosing discussions. This calculator provides the standard formula for informational purposes only; it does not replace an individualized clinical dosing decision.

Is this medical advice?+

No. This calculator is for general education only. It is not medical advice and should not be used to make dosing or treatment decisions — always consult a qualified healthcare professional for dosing calculations specific to your situation.

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