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Bioavailability Calculator

Work out bioavailability instantly with clear inputs, formula shown and shareable results.

About Bioavailability Calculator

Compares dose-normalised exposure after oral and intravenous administration to give absolute bioavailability.

Formula

Absolute bioavailability

F = (AUC oral / dose oral) / (AUC IV / dose IV) x 100

Worked example

With the default values below, Bioavailability Calculator returns Absolute bioavailability of 33.33%. Change any input above and every figure here is recalculated in your browser.

Inputs used

AUC after the oral doseaccepts 0.01–10,000 mg.h/L
40 mg.h/L
Oral doseaccepts 0.1–10,000 mg
500 mg
AUC after the intravenous doseaccepts 0.01–10,000 mg.h/L
60 mg.h/L
Intravenous doseaccepts 0.1–10,000 mg
250 mg

Results

Absolute bioavailability
33.33%
Oral dose multiplier versus intravenous
3.000
Ratio of oral to intravenous AUC
0.667

Step by step

  1. 1Values used
  2. 2Absolute bioavailability
  3. 3Absolute bioavailability= 33.33
  4. 4Oral dose multiplier versus intravenous= 3.000
  5. 5Ratio of oral to intravenous AUC= 0.667

Assumptions and limits

  • The result is derived only from the 4 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 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

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

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

What limits oral bioavailability?

Incomplete absorption and first-pass metabolism in the gut wall and liver.

What is relative bioavailability?

A comparison between two non-intravenous formulations, which is what bioequivalence studies measure.

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