Definition
CPC, or cost per click, is calculated as total ad spend divided by total clicks. It connects CPM and CTR to downstream CPA and ROAS.
CPC formula
CPC = ad spend / clicks
How to calculate CPC (step-by-step)
- Choose a time window and placement mix.
- Sum ad spend for that window.
- Count clicks for the same window.
- Divide spend by clicks to get CPC.
CPC example
If you spend $1,000 and get 800 clicks, CPC = $1.25.
How CPC relates to CPM and CTR
- CPC ~ CPM / (1000 * CTR) when CTR is a fraction.
- Higher CTR lowers CPC for a given CPM.
- If CPM rises, CPC rises unless CTR improves.
CPC vs CPA
- CPA = CPC / CVR, so CPC only matters with CVR.
- Lower CPC does not guarantee lower CPA if CVR falls.
- Use funnel math to decide whether CTR or CVR is the bottleneck.
How to lower CPC without harming CPA
- Improve CTR with stronger creative and tighter message match.
- Refine targeting to reduce low-intent clicks.
- Improve landing page relevance to preserve CVR as CTR changes.
Common mistakes
- Optimizing CPC alone and ignoring CVR or profit.
- Comparing CPC across placements with very different intent.
- Mixing click-based CVR and session-based CVR in the same analysis.