Impressions
The number of times your ad is shown, regardless of whether anyone clicked on it, engaged with it, or even noticed it. One person seeing your ad five times counts as five impressions.
The term comes from print advertising, where an "impression" meant your ad appeared in a publication's print run. Digital impressions work the same way, just at a much bigger scale.
Impressions vs. reach
These two get confused a lot.
Impressions count total displays. If 100 people each see your ad 3 times, that's 300 impressions.
Reach counts unique people. Same scenario: 100 reach.
Impressions will always be equal to or higher than reach. The gap between them tells you your frequency (impressions / reach = average times each person saw your ad).
How impressions relate to pricing
Most social and display ad platforms charge on a CPM (cost per mille) basis, which means cost per 1,000 impressions. Meta, LinkedIn, TikTok, Reddit, programmatic display — they all sell impressions.
Search ads (Google, Bing) usually charge on CPC, so impressions themselves don't cost you anything. You only pay when someone clicks. But impression volume still matters because it determines how many people see your ad, which affects your CTR calculation.
When impressions matter
Brand awareness campaigns. If the goal is getting your name in front of as many people as possible, impressions are a primary metric. You're paying for visibility, and impressions measure that.
Diagnosing delivery issues. If your campaign is active but impressions are low, something is wrong. Your bid might be too low, your audience too narrow, or your ad might have been rejected. Impressions are the first thing to check when a campaign isn't spending.
Calculating other metrics. CTR = clicks / impressions. Frequency = impressions / reach. CPM = (spend / impressions) x 1,000. Impressions are a building block for most of the metrics you actually care about.
When impressions don't matter
High impressions with low engagement means wasted budget. If your ad is getting 500,000 impressions and 12 clicks, the ad isn't resonating. More impressions won't fix a bad creative.
Impressions say nothing about quality. Your ad might technically "show" to someone while it's below the fold on a webpage they never scrolled to. Or it might load in a mobile feed that someone scrolled past in half a second.
This is why viewable impressions (vCPM) exist. They only count when the ad was actually visible on screen. It's a more honest metric, but not every platform offers it.
FAQ
What does "1,000 impressions" mean?
Your ad was displayed 1,000 times. It could have been shown to 1,000 different people once each, or to 200 people five times each, or any combination.
Are more impressions always better?
No. A campaign with 50,000 targeted impressions and a 2% CTR is doing more for your business than one with 500,000 untargeted impressions and a 0.1% CTR.
Do I pay for impressions on Google Search?
No. Google Search uses CPC pricing, so you only pay for clicks. But low impressions on Search means your keywords aren't matching enough queries, or your bids aren't competitive enough.