EPC (earnings per click) and CR (conversion rate) are the two metrics that tell you whether a traffic source is worth scaling. Both have a sample-size problem early on.
What they mean
- EPC — your total earnings divided by total clicks. If you earned $40 across 80 clicks, your EPC is $0.50.
- Conversion rate — conversions divided by clicks, expressed as a percentage. 1 conversion on 80 clicks is 1.25%.
The sample-size problem
With small numbers, both metrics swing wildly. A single conversion on 50 clicks looks like a 2% conversion rate, but the next 50 clicks could yield zero — the "true" conversion rate is somewhere wider than what 50 clicks will tell you.
Rule of thumb: wait for at least 100 clicks per segment before treating EPC or CR as a real signal. Below that, you are mostly looking at noise.
Reading EPC vs CR
They tell you different things. CR tells you how well your traffic and offer match. EPC tells you how profitable that match is given your country mix (T1 traffic at $36 per conversion produces a higher EPC than T3 traffic at $26 even at the same conversion rate).
How you benchmark EPC depends on how you drive traffic:
- Paid traffic: EPC must exceed your CPC. If your CPC is $0.30 and your EPC is $0.45, you're profitable. If EPC is $0.20, you're losing money.
- SEO / webmaster: EPC tells you which content categories are worth scaling. A page sending 500 clicks/month at $0.60 EPC ($300/mo) deserves five more like it; one at $0.10 EPC doesn't.
- Community / forum: EPC tells you which communities deserve your posting bandwidth. A community at $0.80 EPC is worth 4× the time of one at $0.20 EPC.
- Email / content audience: EPC tells you which segments and angles pull the weight. Build more around the high-EPC ones, sunset the low ones.
Slicing by sub-parameter
The most useful thing you can do with reporting is segment by sub-parameter — different campaigns, different audiences, different deeplinks all produce different EPCs. If sub2=female has a $0.60 EPC and sub2=male has a $0.20 EPC, you have learned something actionable about your audience.
For the full playbook on slicing your data — by country, deeplink, day of week, device, and creative — read the in-depth conversion rate optimization guide.