What is CPM? Meaning, Formula, and When It Matters
Also known as: Cost per Mille, Cost per Thousand Impressions
Short answer
CPM is what you pay for one thousand times your ad appears on a screen. A CPM of $25 means a thousand impressions cost $25. CPM prices attention, not clicks and not results.
Formula
CPM = (Ad Spend / Impressions) x 1,000
Example
$500 of ad spend produces 20,000 impressions. CPM = (500 / 20,000) x 1,000 = $25.
The simple way to think about it
CPM is the rent on a billboard per thousand eyes that pass it. A board on a main road costs more than one down an alley, and that is fair.
When CPM matters
- When you compare placements. An expensive placement has to pay for itself in results.
- When CPA rises and you want the cause. If CPM rose and CTR held, blame the auction. If CPM held and CTR fell, blame the creative.
- When the campaign goal really is reach, not conversion.
When CPM does not matter
When you are chasing sales. Nobody pays you for impressions. Do not cut CPM by shifting the ad onto cheap placements that never produce buyers.
Frequently asked questions
- Why is my CPM rising?
- CPM rises when the auction gets busier, the audience is too narrow, or your ad runs on expensive placements. It also rises in shopping season, because many advertisers chase the same people.
- Is a high CPM always bad?
- No. A high CPM on the right audience can produce a cheaper CPA than a low CPM on a random one. Judge the campaign on results, then use CPM to explain the cause.
- What is the difference between CPM and CPC?
- CPM counts per thousand impressions. CPC counts per click. An impression does not mean anyone truly looked, and a click does not mean anyone bought.
Related terms
Your ad numbers are only as accurate as the data behind them
Konektor captures the Click ID and sends conversions that close on WhatsApp, over the phone, or in a shop back to the ad platform.