Loading Dose Calculator

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

About Loading Dose Calculator

Multiplies the volume of distribution by the target concentration and divides by bioavailability to give the loading dose.

Formula

Loading dose

Loading dose = volume of distribution (L) x target concentration (mg/L) / bioavailability

Worked example

With the default values below, Loading Dose Calculator returns Loading dose of 777.8. Change any input above and every figure here is recalculated in your browser.

Inputs used

Body weightaccepts 1–250 kg: 70 kg
Volume of distributionaccepts 0.05–20 L/kg: 0.5 L/kg
Target concentrationaccepts 0.1–500 mg/L: 20 mg/L
Bioavailabilityaccepts 5–100: 90

Results

Loading dose: 777.8 mg
Volume of distribution: 35.00 L
Loading dose per kilogram: 11.11 mg/kg

Step by step

1Values used
2Loading dose
3Loading dose= 777.8 mg
4Volume of distribution= 35.00 L
5Loading dose per kilogram= 11.11 mg/kg

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 2 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

Why give a loading dose at all?

It fills the volume of distribution immediately instead of waiting five half-lives for accumulation.

Is it adjusted for renal failure?

The loading dose usually is not, because it depends on distribution rather than clearance; the maintenance dose is.