# Sample Size Calculator

## Free statistical significance calculator

How many users do you need for **a/b testing** and how long should your tests run?

Our **online sample size calculator** helps you calculate the minimum sample size as well as the duration of your tests based on your audience, your conversions and other information such as the Minimum Detectable Effect. This helps you increase your confidence level before making any decisions to improve your conversion rate. If you need more explanations, all indicators are explained in the FAQ below the calculator.

## How many users do you need?

per variation

## How long should your test run?

Our **statistical significance calculator** also gives you an idea of the duration of your A/B test. For this **A/B test duration calculator** to work, please **fill in the information above**, as well as your average daily traffic on the tested page and your number of variations - including the control version.

You may also be interested in this more in-depth blog post where we discussed how long your A/B test should run.

## How to figure out the Minimum Detectable Effect?

If you have absolutely no clue how to choose this MDE, we've got you covered!

## FAQ

The goal is to provide a simple way to compute the needed amount of visitors required for a test to be statistically significant (e.g. the needed amount of visitors you need to assess that a lift/loss of x% can be trusted with 95% confidence).