Metric comparison
CPC vs CPM vs CPA
By Oliver Wakefield-Smith, Digital Signet. Updated July 2026.
Three pricing models, one funnel. CPM buys attention at the top, CPC buys visits in the middle, CPA buys outcomes at the bottom. The table decides; the bridges convert.
The decision table
| Funnel stage | Audience | Buy on | Why |
|---|---|---|---|
| Awareness | People who have never heard of you | CPM | You are buying memory, not action; impressions are the honest unit |
| Consideration | People comparing options | CPC | You want the visit; pay only when you get it |
| Action | People ready to buy or book | CPC or CPA | CPA once conversion tracking has enough data; CPC with a break-even ceiling until then |
The bridges
Two ratios chain the three models. CTR (clicks over impressions) turns CPM into an effective CPC: CPC = CPM / (1000 x CTR). CVR (conversions over clicks) turns CPC into CPA: CPA = CPC / CVR. Both bridges are worked with tickets on CPC vs CPM and CPC vs CPA. For scale, the 2026 search averages are 6.64% CTR and 8.18% CVR LocaliQ, 2026 data.
Quick answers
What do CPC, CPM and CPA each measure?
CPM is the cost of a thousand ad impressions, CPC the cost of one click, CPA the cost of one acquisition (a customer or enquiry). They price attention, visits and outcomes respectively.
Which single metric should a £500/month advertiser watch?
CPA, or its lead-gen cousin CPL, because it maps to actual business. CPC is the daily tuning dial that drives it. CPM only matters if you are deliberately buying awareness.
How do the three convert into each other?
CPC = CPM / (1000 x CTR), and CPA = CPC / CVR. Two ratios, CTR and CVR, chain all three together.
Vocabulary from zero: CPC in marketing. The chain in practice: clicks to customers.