Adjusted Body Weight Calculator
The Adjusted Body Weight Calculator estimates the dosing weight used clinically when someone weighs well above their ideal body weight (IBW). It finds IBW from height and sex with the Hamwi formula, then applies AdjBW = IBW + 0.4 × (actual weight − IBW). It is an educational reference, not medical advice.
Rates and fees change frequently. Always confirm the current figures
with the official authority before relying on this result.
- Uses Hamwi IBW formula; other formulas (Devine, Robinson) give slightly different results.
- The 0.4 correction factor may differ in some clinical protocols.
- Not a substitute for professional clinical judgement.
Formula
AdjBW = IBW + 0.4 × (Actual Weight − IBW)
IBW (men) = 48.0 + 2.7 kg per inch over 5 ft
IBW (women) = 45.5 + 2.3 kg per inch over 5 ft
- Ideal body weight (IBW) is found from height and sex using the Hamwi formula.
- Adjusted body weight adds 40% of the weight carried above IBW: AdjBW = IBW + 0.4 × (actual − IBW).
- It is mainly used for drug dosing when actual weight exceeds IBW by more than about 30%; below that, actual body weight is normally used.
- This is an educational reference and not a substitute for clinical judgement.
Example Calculation
Inputs
- Sex: male
- Actual Body Weight: 90 kg
- Height: 170 cm
A 170 cm man has IBW ≈ 65.6 kg. At 90 kg actual weight, AdjBW = 65.6 + 0.4 × (90 − 65.6) ≈ 75.4 kg.
Frequently asked questions
What is adjusted body weight?
It is a dosing weight between ideal and actual body weight, used clinically when a person weighs substantially more than their ideal body weight.
When is it used instead of actual weight?
Typically when actual weight exceeds ideal body weight by roughly 30% or more, for certain medications. Otherwise actual body weight is usually used.
How is ideal body weight calculated?
With the Hamwi formula: 48.0 kg (men) or 45.5 kg (women) for the first 5 ft of height, plus 2.7 kg (men) or 2.3 kg (women) per inch above that.
Why the 0.4 factor?
It reflects that excess body mass is only partly metabolically active, so just a fraction of the weight above IBW is added.
Is this medical advice?
No. It is an educational estimate; dosing decisions should be made by a qualified clinician.
Related calculators
Ideal Weight Calculator Popular Ideal Weight Calculator is a health and wellness calculator that helps you calculate weight values or weight conversions between unit systems. The formula used is: Hamwi (men): 48.0 + 2.7 kg per inch over 5 ft\nHamwi (women): 45.5 + 2.3 kg per inch over 5 ft\nDevine (men): 50.0 + 2.3 per inch over 5 ft\nDevine (women): 45.5 + 2.3 per inch over 5 ft\nRobinson (men): 52.0 + 1.9 per inch over 5 ft\nRobinson (women): 49.0 + 1.7 per inch over 5 ft\nMiller (men): 56.2 + 1.41 per inch over 5 ft\nMiller (women): 53.1 + 1.36 per inch over 5 ft. Enter values using the units shown next to each input field (e.g. kg, cm, years). BMI Calculator Popular Calculate your Body Mass Index (BMI) from your height and weight and see which category it falls into. Enter your weight and height and this calculator returns your BMI, its category, and the healthy weight range for your height. Lean Body Mass Calculator Lean Body Mass Calculator is a health and wellness calculator that helps you calculate lean body mass values from your input data. The formula used is: Boer (men): LBM = 0.407 × weight + 0.267 × height(cm) − 19.2\nBoer (women): LBM = 0.252 × weight + 0.473 × height(cm) − 48.3\nHume (men): LBM = 0.3281 × weight + 0.3393 × height(cm) − 29.534\nHume (women): LBM = 0.29569 × weight + 0.41813 × height(cm) − 43.293. Enter values using the units shown next to each input field (e.g. kg, cm, years).