How to Ad rotation works?

A preference that determines which ad in your ad group should show (when you have multiple ads). Ad rotation settings are helpful because they give you the ability to request how your ads are shown. For example, you can request to have your successful ads show more often or indicate that you’d like your ads to be shown more evenly.

If you have more than one ad in your ad group, we’ll rotate which ad shows depending on your ad rotation setting.

The ad rotation settings are on your campaign’s “Settings” tab, in the “Advanced settings” section. There you’ll find 4 ad rotation settings to choose from:

Ad rotation setting What it does Keep in mind
Optimize for clicks (default setting) Gives preference to ads that are expected to attract more clicks than other ads in the ad group, based on your past clickthrough rates (CTRs). Google will try to show those ads more often than other ads in your ad group to help you gain more clicks and impressions.
Optimize for conversions Gives preference to ads that are expected to provide moreconversions, like purchases and sign-ups, than other ads in the ad group. Your ad group might receive fewer clicks, but it’s likely to receive more conversions, which can result in an improved return on investment. If there isn’t enough conversion data to determine which ad is likely to provide the most conversions, ads will rotate to optimize for clicks.
Rotate evenly Gives equal preference to all active ads in your ad group, regardless of how each ad performs. Each ad will be eligible to show an equal number of times, but the actual impressions — how often each is actually shown — can differ across ads based on a number of factors.In general, rotating evenly allows ads with lower clickthrough rates and conversion rates to show more often, so this option could result in a lower average position or fewer clicks and conversions.

With this option, if ads in an ad group are unchanged for 90 days, the ad rotation in this ad group will automatically begin to optimize for clicks. However, if the campaign is usingConversion Optimizer or Enhanced CPC, it will optimize for conversions.

Rotate indefinitely Similar to the “Rotate evenly” setting, this option delivers your ads more evenly into the ad auction, but does so for an indefinite amount of time and does not optimize. Because this option allows lower-performing ads to run as often as higher-performing ads for an indefinite period of time, this option is not recommended for most advertisers.

You can see how often each ad has been shown in relation to the rest of the active ads in the same ad group. You’ll find that data on your campaign’s “Ads” tab, in the “% served” column.

Keep in mind that the ad with the highest CTR may not always be the one expected to get the most clicks. That’s because the number of clicks an ad is expected to get is also affected by how often an ad is eligible to enter an auction. Expected CTR is only one factor of Ad Rank, which also considers landing page experience and ad relevance (among other factors) when determining your ad’s position and whether it will show at all. So a more relevant ad with a better landing page experience but a lower expected CTR could be eligible to show on search results more often. That can, in turn, lead to a higher overall number of expected clicks.