Steady State Time Calculator

Work out steady state time instantly with clear inputs, formula shown and shareable results.

About Steady State Time Calculator

Calculates how long repeated dosing takes to approach steady state, since accumulation follows the same exponential as elimination.

Formula

Time to steady state

Fraction of steady state = 1 - 0.5^(number of half-lives); solving gives half-lives = ln(1 - fraction) / ln 0.5

Worked example

With the default values below, Steady State Time Calculator returns Time to reach the target of 30.35. Change any input above and every figure here is recalculated in your browser.

Inputs used

Elimination half-lifeaccepts 0.1–500 h: 6 h
Percentage of steady state requiredaccepts 50–99.9 %: 97 %

Results

Time to reach the target: 30.35 h
Half-lives required: 5.06
Percentage of steady state at five half-lives: 96.88%
Time to target: 1.26 days

Step by step

1Values used
2Time to steady state
3Time to reach the target= 30.35 h
4Half-lives required= 5.06
5Percentage of steady state at five half-lives= 96.88
6Time to target= 1.26 days

Assumptions and limits

The result is derived only from the 2 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 is five half-lives the usual rule?

It reaches about 97% of steady state, which is within measurement error of the plateau.

Can steady state be reached sooner?

Yes, with a loading dose, which fills the volume of distribution immediately.