Definition
CTR (click-through rate) is the share of impressions that turn into clicks. It is a creative-market fit signal and a key input to CPC and CPA.
CTR formula
CTR = clicks / impressions
How to calculate CTR (step-by-step)
- Choose a time window and placement mix.
- Count impressions for that window.
- Count clicks for that same window.
- Divide clicks by impressions and express as a percent.
CTR example
If an ad gets 2,000 clicks from 100,000 impressions, CTR = 2,000 / 100,000 = 2%.
How CTR affects CPC and CPA
- Higher CTR generally lowers CPC for a given CPM.
- Lower CPC can reduce CPA only if CVR is stable.
- CTR gains from low-intent clicks can hurt CVR and raise CPA.
How to improve CTR (without harming CVR)
- Tighten message-match between ad and landing page.
- Test hooks that speak to the top pain point or outcome.
- Use proof or specificity (numbers, time saved, results).
- Segment by intent and tailor creative per audience/placement.
CTR vs CVR
- CTR is a creative signal; CVR is an offer + landing-page signal.
- Optimize CTR only if CVR and CPA remain healthy.
- Use the funnel view (CPM -> CTR -> CVR -> CPA) to find the real bottleneck.
Common mistakes
- Comparing CTR across placements with very different intent.
- Optimizing CTR alone and ignoring profit or CPA.
- Mixing link CTR with all-click CTR in the same trend line.