Duration Estimator
Calculator Configuration
Recommended: For a more comprehensive calculator that combines sample size, duration estimation, and comparison tables, check out our Sample Size and Test Duration Calculator.
How it works
Watch a demo of the Duration Estimator ⤴
What is Duration Estimation?
Duration estimation helps you determine how many days it will take to complete an experiment based on your available traffic and desired sample size per variant.
Calculating Duration Given a Sample Size
If you already know your target sample size per variant (e.g. from an MDE or power calculation), you can estimate how long your test needs to run by factoring in your available traffic and how that traffic is split across variants.
This is especially useful when planning test timelines or comparing the feasibility of tests with different numbers of variants.
The Formula
We calculate the number of days required using the formula:
Where:
- n is the sample size per variant
- T is the total daily traffic available to the experiment
- k is the number of variants (including control), assuming equal traffic split
- is the daily traffic allocated to each variant
This formula assumes traffic is distributed evenly across all variants.
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