Frequency capping is a feature that limits the number of times that your ads appear to the same person on the Display Network. 

Frequency is the average number of times that a unique user sees your ad in a position of '1' over a given time period (day, week, or month).

It's important to use frequency capping to prevent annoying your potential customers, especially in remarketing to them.

When you turn on frequency capping for a campaign, you set a limit for the number of impressions that you'll allow an individual user to have per day, per week or per month. You also choose whether the limit applies to each ad, ad group, or campaign.

Only impressions that were viewable count towards frequency caps. An ad is counted as viewable when 50% or more of the ad is shown for one second or longer for display ads and two seconds or longer for video ads.

Frequency capping is not available as an option for the Search campaign but is an option for the Display campaign and Youtube campaign.

To access Frequency capping:

You need to switch your Google Ad account to expert mode first.

1. Once signed into your Google Ads account, click the Tools icon  in the top right corner.

2. Select Switch to Expert Mode.

Once you’ve switched to Expert Mode, you’ll be able to access the full Google Ads experience and create all Google Ads campaign types, e.g. Search, Display, Video, App, Shopping.

Please note that once your account is switched to “Expert Mode”, you cannot revert your account to Smart Mode. However, you can always edit your Smart campaigns from Expert Mode, just like you would edit any other campaign.

Then try to set up your frequency capping again. However, this only applies to Display and Video campaigns.

If you are setting up a frequency cap on a new campaign, you can do the steps below:

1. Sign in to your Google Ads account.

2. Select All campaigns in the navigation panel.

3. Click Campaigns in the page menu.

4. Click the plus button  and select New campaign.

5. Select your campaign goal and click Continue.

6. Select your campaign types and click Continue.

7. Click Additional settings.

8. Select Frequency capping.

9. Enter the number of impressions (or views for video campaigns). The value must be a whole number (such as 4, not 4.5).

10. Select a time interval (per day, week, month, or a combination).

11. Once the rest of your campaign is set up, click Create campaign.

This is if you are to set up frequency cap on an existing campaign:

1. Sign in to your Google Ads account.

2. Select All campaigns in the navigation panel.

3. Click the name of the campaign to be delivered.

4. Select Settings on the page menu.

5. Click Additional settings.

6. Select Frequency capping.

7. Enter the number of impressions (or views for video campaigns). The value must be a whole number (such as 100, not 100.5).

8. For display campaigns only, select a time interval (per day, week, or month).

9. Click Save.