How long should I run tests for in Google Ads?

I often get asked, “how long do you run tests for?” whether it’s testing ad copy, different bid strategies or budget etc. The rule of thumb I like to apply is 30 days. A month will usually give enough time for most tests to generate enough “meaningful” data in order to make decisions on the test outcome.

By “meaningful”, I’m referring to the period of time that will cover the most likely fluctuations a campaign may see eg. peaks and troughs of conversions (eg. days of the week; month end and mid month variations; seasonality; impact of weather/social & political factors etc.)

Of course you can run tests over a shorter period eg. 14 days, which generally will give the Google AI enough time to make an impact on bid strategies, but you really do need a good volume of impressions (eg. 5000+) before you could feel the test outcome has some reliability. Without enough data, you could be missing opportunities that will serve your longer campaign goals well.