Metric comparison
CPC vs CPM
By Oliver Wakefield-Smith, Digital Signet. Updated July 2026.
CPC prices the click; CPM prices a thousand impressions, clicks or not. Same auction machinery, opposite risk: with CPC the platform carries the risk of nobody clicking, with CPM you do.
CPC
Cost per click
Charged when someone clicks
- You pay only for visitors, never for views
- Native to search, where intent is high
- Budget maps directly to traffic: budget / CPC = clicks
CPM
Cost per thousand impressions
Charged per 1,000 times the ad is shown
- You pay for exposure whether or not anyone clicks
- Native to display and social awareness buying
- Cheap reach; the click risk sits with you
Use this when
CPC: you want visitors and enquiries you can count this month.
CPM: you want reach and remembering, and clicks are not this campaign's job.
Google's definitions: Google Ads Help, CPC Google Ads Help, CPM
The bridge between them
eCPC from CPM · worked
Effective CPC = CPM / (1000 x CTR). The numbers above are an illustration of the formula, not a benchmark. Run the comparison with your own CPM and CTR before moving budget; a $10 CPM at a 0.5% CTR is a $2.00 effective CPC, twice as dear per visitor.
Which wins for a local budget
For a local service that needs the phone to ring, clicks are the product: buy on CPC and judge by the conversion chain. CPM earns its place when you have a launch or a brand to seed and can afford visibility without immediate enquiries. The three-way decision with CPA is on CPC vs CPM vs CPA; the video cousin is CPC vs CPV, and Meta's auction, where both models coexist, is on the Facebook page.