In one sentence: Impression share is the percentage of the ad auctions your ad was eligible for that it actually appeared in, so if your ad shows up in four out of every ten eligible searches, your impression share is 40 percent.
Most ad reporting tells you what happened. This many clicks, this much spent, this many calls. Impression share is the rare metric that tells you what did not happen, because it has a denominator, and the denominator is every auction you were in the running for.
As a worked example, say your ads were eligible for a thousand searches last month and showed on three hundred of them. Impression share is 30 percent. The other seven hundred searches went to somebody else, and until you look at this number they are invisible to you. Clicks and cost say nothing at all about the ones you never appeared in.
There are only two broad reasons an eligible ad does not show. Either the money ran out, meaning the daily budget was already spent by the time the search happened, or the ad did not clear the bar, meaning your bid and your relevance were not enough to earn a spot. Ads reporting splits the missing share along those two lines, and the fix is different for each. One is a budget conversation. The other is an account quality conversation, and spending more will not solve it.
A local service business is not trying to be everywhere. It wants a short list of services in a short list of towns. That makes this metric unusually readable for you: it comes close to a direct answer to the question of whether you were even present when a neighbor searched for the thing you sell.
It also breaks out by campaign and by area, which is where it earns its keep. You can be showing for nearly every search in the town your shop sits in and be almost absent in the suburb you have spent a year trying to break into, while the account total looks perfectly healthy. The average hides the hole. The breakdown shows it.
The trap is reading a low number as automatically bad and a high one as automatically good. Owning nearly every impression on a keyword list full of tire-kickers is an expensive way to be visible for the wrong searches, and the final slice of impression share is the most costly you will ever buy, because those are the auctions somebody else wanted more than you did. Read it next to what the clicks turned into, and for how that fits with the rest of the levers in an account, our Google Ads page lays out the work.
Impression share moves when Ad Rank moves, and Ad Rank depends partly on Quality Score, which is Google's read on how relevant your ad and your landing page are to the search someone typed. It is also the closest paid cousin to share of voice, the broader idea of how much of a market's attention you hold, and it feeds directly into what you pay per click.
Almost never. The last stretch costs the most per click, because you are buying the auctions a competitor was willing to pay more for, and that money usually does more work in a service or a town where you are barely showing up at all. Full coverage is a fair goal for a narrow set of searches you cannot afford to miss, not for a whole account.
No. It only counts auctions on the platform you advertise on, and only the searches your campaigns were eligible for in the first place. Someone who found you through the map results, a neighbor's recommendation, or a competitor you never bid against is nowhere in the number. It measures your presence in a slice of the market, not the market.
Google Ads management · Ad Rank · Quality Score · Share of voice · Cost per click · All glossary terms · Plain-English answers · All services
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