Follow the steps below to add an extra custom size to your ad set:
In the “single view” click on the sizes dropdown in the toolbar.
Click on “add ad” from the dropdown menu.
Click on the “Add size” button.
Enter a name, width and height and click on “Add custom size”
Note that not all networks allow all custom sizes so before you add your custom size make sure your network supports it.
Do you need to have the same size more than once in your ad set?
This is possible. Simply add the size you need as a custom size again. By default, when a size is added in an ad set, you can't select it again. However, you can manually add it as a "custom size" as many times as needed.
We hope the information in this article was useful to achieve your goal. If there is anything else we can help you with and you couldn't find it in our help center, don't hesitate to contact us by chat. We are always ready to help you.