What interactions measure
Different ad formats ask for different things. A search ad wants a click. A video ad wants someone to watch. A call ad wants the phone to ring. Rather than keep a separate headline column for each format, Google Ads reports one column called Interactions, which holds whichever action counts as the primary one for the format being reported, together with an average cost for that action.
So the column does not describe a single event. In a search campaign an interaction is a click. In a video campaign it is a view, counted by that format’s own rules. In a call ad it is a call. The number is honest within any one format and becomes meaningless the moment several formats are added together.
Why interactions matter
They give a mixed account one line that can be read across the whole thing. If you are running search, video and display side by side, a single column showing whether activity is rising or falling, and what each one typically costs, is genuinely useful in a summary table, as long as everyone knows what it contains.
Within a single campaign type, cost per interaction is also a clean, fast health check. It moves when competition rises, when creative tires, or when targeting is widened into cheaper and less relevant places, often before conversion figures have collected enough data to show anything at all.
Common mistakes with interactions
Summing them across formats is the first and worst. A video view and a search click are not the same commitment from the person who made them, and a total that mixes them will always be dominated by whichever format is cheapest to trigger.
Comparing cost per interaction across formats is the same mistake in a different shape. Video interactions are far cheaper to buy than search clicks, so a table ranked by cost per interaction will make video look like the best-performing thing in the account, regardless of whether it produced any business.
The third is presenting interactions as results. They record that something happened at the ad, not that anything happened for the company. A report built on interactions can look busy while enquiries sit flat, and that is exactly the report a client should push back on.
How to act on it
Segment before you read. Split by campaign type, or by network, so each figure sits with others of its own kind, and check the interaction rate alongside it — the raw count rises with spend, the rate does not.
In anything going to a client or a board, rename the column to the action it actually contains: clicks, views or calls. It costs you nothing and it stops an honest number from being read as a bigger one. Then keep decisions on conversions and cost per acquisition, and let interactions do the smaller job they are good at — telling you quickly whether the account is still reaching people, which matters most on YouTube and video campaigns where conversions are slower to arrive than views.