How this calculator works
Impressions are the number of times an ad was displayed, clicks are the times it was clicked and cost is what the campaign was charged. Click-through rate divides clicks by impressions. Cost per click divides cost by clicks. CPM divides cost by impressions and multiplies by one thousand, because CPM prices one thousand impressions. The four figures describe the same campaign from different angles: a low CTR with a steady CPC usually means the creative is not attracting the right viewers, while a rising CPM with steady clicks means each display is becoming more expensive.
Formula
CTR = clicks / impressions × 100. CPC = cost / clicks. CPM = cost / impressions × 1,000. Clicks per thousand impressions = clicks / impressions × 1,000.
Worked example
A campaign with 100,000 impressions, 2,000 clicks and $500 of cost has a CTR of 2%, a CPC of $0.25 and a CPM of $5.00. That is 20 clicks per thousand impressions.
Advertisement
Frequently asked questions
Should I use CPM or CPC to compare campaigns?
Use both. CPM measures the cost of buying attention and CPC measures the cost of buying visits. A campaign can have a low CPM and a high CPC if its click-through rate is poor, so the two together show where the problem lies.
Why must clicks be less than impressions?
Each impression can be clicked at most once in this model, so more clicks than impressions would mean some impressions were clicked twice. The calculator rejects that as a data error.
How do I get cost from CPM?
Cost = CPM × impressions / 1,000. The CPM calculator on this site solves for cost, CPM or impressions when you know the other two.