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Adjusted Body Weight Calculator

Work out adjusted body weight instantly with clear inputs, formula shown and shareable results.

About Adjusted Body Weight Calculator

Adjusted body weight is used for drug dosing in obesity, because adipose tissue is metabolically less active but still holds some drug. The convention adds 40% of the excess over ideal weight: at 110 kg against a 70.5 kg ideal, the adjusted figure is 86.3 kg. It applies only when actual weight exceeds ideal weight.

Formulas

Adjusted body weight

ABW = IBW + 0.4 x (actual weight - IBW)

Applies only when

actual weight exceeds ideal body weight

Worked example

With the default values below, Adjusted Body Weight Calculator returns Adjusted Body Weight of 86.3. Change any input above and every figure here is recalculated in your browser.

Inputs used

Actual body weightminimum 1 kg
110 kg
Heightminimum 100 cm
175 cm
Sexone of Male, Female
Male

Results

Adjusted Body Weight
86.3 kg
Ideal Body Weight
70.5 kg
Weight Above Ideal
39.5 kg
Percentage Above Ideal
56.1%

Step by step

  1. 1Values used
  2. 2Adjusted body weight
  3. 3Applies only when
  4. 4Adjusted Body Weight= 86.3 kg
  5. 5Ideal Body Weight= 70.5 kg
  6. 6Weight Above Ideal= 39.5 kg
  7. 7Percentage Above Ideal= 56.1

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • These figures are population-average estimates, not a medical assessment or diagnosis. Body composition equations carry errors of several percentage points, and healthy ranges vary with age, ethnicity, muscularity and medical history. Discuss weight or body composition goals with a qualified clinician or dietitian.
  • This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

These figures are population-average estimates, not a medical assessment or diagnosis. Body composition equations carry errors of several percentage points, and healthy ranges vary with age, ethnicity, muscularity and medical history. Discuss weight or body composition goals with a qualified clinician or dietitian.

Frequently Asked Questions

Why 40% of the excess?

It approximates the share of extra body mass that is metabolically relevant lean tissue and perfused adipose tissue for most drugs.

Which weight should be used for a given drug?

It depends on the drug's distribution. Hydrophilic drugs use ideal or adjusted weight; lipophilic ones often use total body weight.

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