Imagine you have this great new idea for an e-mail you send to all your customers. You are obviously quite certain that this new picture will drastically boast your conversion, but after reading about the power of Experiments and A/B testing, you decide to run a quick test…

First: Good for you! 🙂

Before you setup the test, it is important to see what sample size you need to be able to have a solid result of your test.

Fortunately, there are also tools for this.

• This one from AB testguide is easy to use, and you can use it before you start your test and after you have the results
• Or this one from unbounce. Just fill in some basic numbers and it will tell you how long your test should run.

And if you want to understand more about power and type I and type II errors, read this article!