Adjusted Body Weight Calculator
Calculate your ideal body weight, adjusted body weight, and other nutritional metrics for medical and health purposes.
Your Information
Calculation Formulas
Ideal Body Weight (IBW):
• Men: 50 kg + 2.3 kg per inch over 5 feet
• Women: 45.5 kg + 2.3 kg per inch over 5 feet
Adjusted Body Weight (ABW): IBW + 0.4 × (Actual Weight - IBW)
BMI: Weight (kg) / Height (m)²
Your Results
Your Adjusted Weight
For nutritional assessment purposes
Underweight
BMI < 18.5
Normal
BMI 18.5-24.9
Overweight
BMI 25-29.9
Obese
BMI ≥ 30
About Adjusted Body Weight
Adjusted body weight (ABW) is used for nutritional assessments and medication dosing for overweight and obese individuals.
It provides a more accurate estimation of metabolic mass than using actual body weight or ideal body weight alone.
ABW is particularly important for calculating accurate nutritional requirements and drug dosages.
Adjusted Body Weight Calculator
Quickly calculate Ideal Body Weight using the Devine formula and Adjusted Body Weight for nutrition and medication dosing. Use the calculator above, read below for formulas, step by step worked examples, and clinical guidance.
Why Ideal Body Weight and Adjusted Body Weight matter
Ideal Body Weight and Adjusted Body Weight are used to estimate the weight value clinicians use for nutrition plans and drug dosing when a patient’s actual total body weight does not reflect metabolically active tissue. Adjusted Body Weight reduces the risk of overdosing drugs whose volume of distribution or clearance does not scale with fat mass. (Clinical dosing guidance varies by drug consult pharmacy/local guidelines.)
Formulas
Devine Ideal Body Weight (kg)
Male:
IBW = 50.0 + 2.3 × (height in inches − 60)(Devine).Female:
IBW = 45.5 + 2.3 × (height in inches − 60).
Adjusted Body Weight ABW = IBW + 0.4 × (Actual Body Weight − IBW)
(0.4 = adjustment factor commonly used; some institutional protocols use 0.3 or allow either 0.3/0.4. Check local guidance).
BMI for context: BMI = Weight (kg) / Height (m)^2
Step by step worked examples
Example 1 (Male, height 180 cm, actual weight 110.0 kg)
Convert height to inches: 1 inch = 2.54 cm, height =
180 ÷ 2.54.180 ÷ 2.54 = 70.86614173228346… ≈ 70.87 in,round to 70.9 in or use exact decimal in calculator. (For Devine the formula uses whole inches commonly; we’ll use 71 in for clarity.)
Using 71 in (5 ft 11 in).- Calculate IBW male:
Step A:
Actual − IBW = 110.0 − 75.3 = 34.7.Step B:
0.4 × 34.7 = 0.4 × 30 + 0.4 × 4.7 = 12.0 + 1.88 = 13.88.Step C:
ABW = IBW + 13.88 = 75.3 + 13.88 = 89.18 kg.
Result: IBW = 75.3 kg, ABW = 89.18 kg.
Example 2 (Female, height 160 cm, actual weight 85.0 kg)
Convert height to inches:
160 ÷ 2.54 = 62.99212598425197 ≈ 63 in(5 ft 3 in).
Calculate IBW (female):
height − 60 = 63 − 60 = 3.- 2.3 × 3 = 6.9.
- IBW = 45.5 + 6.9 = 52.4 kg
Calculate ABW:
Actual − IBW = 85.0 − 52.4 = 32.6.0.4 × 32.6 = 0.4 × 30 + 0.4 × 2.6 = 12.0 + 1.04 = 13.04.
- ABW = 52.4 + 13.04 = 65.44 kg
Result: IBW = 52.4 kg, ABW = 65.44 kg.
Clinical use, limitations & practical tips
When to use ABW: Many protocols recommend ABW when TBW is substantially greater than IBW (commonly >20–30% above IBW). ABW is frequently used for dosing some antimicrobials and for nutritional requirement estimation. Always check the drug specific guidance (some drugs use TBW for loading dose and ABW for maintenance).
Adjustment factor: 0.4 is the most commonly used factor; some institutions use 0.3 (document both and state which you follow). Cite your local protocol if available.
Clinical disclaimer: This tool is educational only. Not a substitute for clinical judgment. Confirm drug dosing with pharmacy and local protocols.
FAQs
Q: When should I use adjusted body weight instead of total body weight?
A: Use ABW when TBW substantially exceeds IBW and when drug distribution/clearance are not proportional to adipose tissue. Check drug specific dosing guidelines.
Q: Why 0.4 in the ABW formula?
A: 0.4 (40%) is an empiric compromise between IBW and TBW that estimates metabolically active tissue in obesity; some protocols allow 0.3. Cite your institutional guideline.