CPM vs CPC vs CPA: Which Metric Should You Use?
CPM, CPC and CPA answer different questions about campaign efficiency.
CPM
CPM focuses on exposure. It is useful when your primary objective is reach, awareness or comparing impression costs across placements.
CPC
CPC focuses on paid traffic. It is useful when clicks are the immediate objective and you want to compare the cost of generating visits.
CPA
CPA focuses on completed actions. It is usually more meaningful when the campaign is optimized for leads, signups or purchases.
How to compare them
Do not judge a campaign using one metric in isolation. A low CPM can still produce an expensive CPA if the audience does not click or convert.
Practical takeaway
Use the metric that matches the business question you are trying to answer. When several metrics describe different stages of the same workflow, compare them together rather than optimizing one in isolation.