Level: Intermediate
Comparing raw CPC or CPA numbers across platforms priced differently can be misleading; effective CPM normalizes everything to a comparable basis.
The Formula Converts Any Pricing Model to a Common Unit
eCPM = (total cost ÷ total impressions) × 1,000, letting you compare a CPC-priced campaign against a CPM-priced one on the same basis.
Use It to Compare Platforms Fairly
A platform charging a higher CPC might still deliver a lower effective CPM if its click-through rate is meaningfully higher, which raw CPC comparison alone would miss.
Watch for Placement-Level Variation
eCPM can vary significantly across placements within the same platform, making it worth calculating at the placement level, not just the campaign level.
Next step: Use the Sales Letter Writer to recognize that a favorable eCPM still depends on strong creative to actually convert that efficiently-purchased attention into a result.