If you're new to digital advertising, the alphabet soup of metrics can be overwhelming. CPM, eCPM, CTR, RPM, viewability, fill rate — what does it all mean, and which metrics actually matter for your revenue?
This guide cuts through the jargon and explains every key ad metric in plain English.
Revenue Metrics
CPM (Cost Per Mille)
What it is: The price an advertiser pays for 1,000 ad impressions.
Formula: (Total Ad Spend ÷ Total Impressions) × 1,000
Example: If an advertiser pays $5 for 2,000 impressions, the CPM is $2.50
Why it matters: The primary pricing metric in programmatic advertising. Higher CPM = more revenue per impression.
eCPM (Effective CPM)
What it is: The actual revenue earned per 1,000 impressions, regardless of the pricing model used.
Formula: (Total Revenue ÷ Total Impressions) × 1,000
Why it matters: eCPM lets you compare performance across different ad units, formats, and demand sources on an apples-to-apples basis.
RPM (Revenue Per Mille)
What it is: Revenue earned per 1,000 page views (not impressions).
Formula: (Total Revenue ÷ Total Page Views) × 1,000
Why it matters: RPM gives you a holistic view of how well your entire page is monetized, accounting for all ad units on the page.
💡 Key difference: CPM/eCPM is per 1,000 ad impressions. RPM is per 1,000 page views. A page with 3 ad units will have an RPM roughly 3x its eCPM.
Performance Metrics
CTR (Click-Through Rate)
What it is: The percentage of ad impressions that result in a click.
Formula: (Clicks ÷ Impressions) × 100
Typical range: 0.05% – 0.5% for display ads
Why it matters: Higher CTR indicates more engaging ads. Some pricing models (CPC) pay per click, making CTR directly tied to revenue.
Viewability
What it is: The percentage of ad impressions that were actually visible to users.
IAB standard: An ad is "viewable" if 50% of its pixels are visible for at least 1 continuous second (2 seconds for video).
Why it matters: Advertisers increasingly only pay for viewable impressions. Higher viewability = higher CPMs.
Fill Rate
What it is: The percentage of ad requests that are filled with an actual ad.
Formula: (Filled Impressions ÷ Total Ad Requests) × 100
Why it matters: Unfilled impressions = zero revenue. A fill rate below 80% suggests you need more demand sources.
Complete Metrics Reference
| Metric | Full Name | Formula | Good Benchmark |
|---|---|---|---|
| CPM | Cost Per Mille | Spend / Impressions × 1000 | $1–$5 (display) |
| eCPM | Effective CPM | Revenue / Impressions × 1000 | $1–$5 (display) |
| RPM | Revenue Per Mille | Revenue / Page Views × 1000 | $3–$15 |
| CTR | Click-Through Rate | Clicks / Impressions × 100 | 0.1–0.3% |
| Viewability | — | Viewable Imps / Total Imps × 100 | 60%+ |
| Fill Rate | — | Filled Imps / Ad Requests × 100 | 85%+ |
| CPC | Cost Per Click | Spend / Clicks | Varies by niche |
| CPV | Cost Per View | Spend / Video Views | $0.01–$0.05 |
How to Improve Your Key Metrics
Improve eCPM
- Implement header bidding to increase competition
- Add Google AdX through a partner like Pubixa
- Optimize ad placement for better viewability
- Use private marketplace deals for premium inventory
Improve Viewability
- Place ads above the fold or in high-scroll areas
- Use sticky ad units (like Pubixa's FootAd and HeadAd)
- Reduce page load time
- Avoid placing too many ads below the fold
Improve Fill Rate
- Add more demand sources through header bidding
- Lower your price floors (but not too much)
- Ensure your ad tags are correctly implemented
- Use Pubixa's AdSuite for out-of-page placements with high fill rates