CTR, CPC and RPM appear in digital advertising reports, but they describe different parts of the process. Mixing them up can lead to incorrect conclusions about performance. The first step is to check whether a metric describes clicks, advertiser cost or publisher earnings—and what denominator it uses.
Click-through rate (CTR)
CTR is the percentage of measured impressions that led to a click. If an eligible report shows 125 clicks and 25,000 impressions, CTR is 0.50%. It describes the observed relationship between clicks and impressions; it does not, by itself, tell you whether the traffic or revenue is valuable.
Cost per click (CPC)
CPC generally describes cost per click from the perspective of an advertiser or campaign, though exact reporting definitions vary by platform. Publisher earnings per click can differ from an advertiser's cost because platform fees, product rules and reporting methods differ. Do not use a CPC figure as if it were automatically the publisher's payout per click.
Revenue per thousand (RPM)
RPM summarizes estimated earnings relative to a chosen denominator. Page RPM uses pageviews; impression RPM uses ad impressions. Google's documentation explains that RPM is a comparative metric and is calculated by dividing estimated earnings by the chosen count, then multiplying by 1,000. See Google's RPM definition.
Quick comparison
| Metric | Core question | Basic relationship |
|---|---|---|
| CTR | What share of impressions generated clicks? | Clicks ÷ impressions × 100 |
| CPC | What is the reported cost per click? | Reported click cost ÷ clicks |
| Page RPM | What earnings were associated with 1,000 pageviews? | Earnings ÷ pageviews × 1,000 |
| Impression RPM | What earnings were associated with 1,000 ad impressions? | Earnings ÷ impressions × 1,000 |
Compare like with like
Use the same date range, currency, property and measurement definitions. If comparing two ad placements, consider their page location, loading behavior, viewability and user experience. A higher CTR does not justify misleading labels, accidental-click design or any behavior that violates platform rules.
Calculate CTR
Enter clicks and impressions in the AIVUV CTR Calculator. For a revenue-efficiency ratio, use matching data in the Page RPM Calculator instead.
A simple diagnostic sequence
If CTR changes from one reporting period to another, do not jump directly to a conclusion about earnings. First confirm impressions were counted on the same basis. Next compare placements or page types where the platform provides reliable breakdowns. Then check whether the change coincided with a content update, layout change or traffic-source shift.
CTR alone does not show whether clicks were valuable, whether publisher earnings increased, or whether users found the page helpful. Similarly, CPC and RPM can move for different reasons. Each number describes a different part of the advertising process.
Which metric should you check first?
| Question | Useful starting metric | What to check next |
|---|---|---|
| Did the share of impressions generating clicks change? | CTR | Matched impressions, placement and traffic mix |
| What reported cost was associated with clicks? | CPC | Platform definition and advertiser-side report |
| How did earnings compare with traffic volume? | Page RPM or impression RPM | Use the denominator that matches the question |
Never change a page to encourage accidental clicks or disguise ads as navigation. Good measurement must remain within the publisher platform's current policies and prioritize a clear user experience.
Sources and further reading
The sources below support definitions or general methods discussed in this guide. AIVUV's examples are illustrative and do not replace platform-specific reporting or professional guidance.