Ad glossary · Performance metrics · Checked 2026-10-23
What is CPM: how cost per 1,000 impressions is worked out and why it rises
CPM is the average cost of 1,000 ad impressions: amount spent divided by impressions, times 1,000.
- English
- CPM (cost per 1,000 impressions)
- Also called
- Cost per mille, cost per thousand impressions
- Area
- Performance metrics
How it is used
CPM is what it costs to be seen, and it moves most with competition, audience size and season. If CPM rises while CTR and conversion rate hold, the change is in the market, not on your page.
CPM is the price of being seen
Meta’s auction picks the ad with the highest total value (the bid, the estimated action rate and ad quality) so CPM reflects the market and also how relevant the system thinks your ad is.
Common reasons CPM rises: everyone raising budgets before a peak season, an audience that is too small, and creative judged lower quality.
Read CPM with what comes after it
A dear CPM is not necessarily bad: if CTR and conversion rate are higher too, CPA can still come out lower. Chasing cheap CPM by audience or placement often buys impressions nobody clicks.
Formula: plug in your numbers
CPM = amount spent ÷ impressions × 1,000
Example
NT$12,000 spent, 80,000 impressions: CPM = 12,000 ÷ 80,000 × 1,000 = NT$150. At 1.5% CTR, 1,000 impressions bring 15 clicks, so CPC is 150 ÷ 15 = NT$10.
Not to be confused with
“Cost per 1,000 Meta Accounts reached”: the divisor is reach, not impressions, so it comes out higher than CPM.
FAQ
What should I do when CPM suddenly rises?
First check whether the whole market is rising (before a peak season, competitors adding budget), then whether your audience is too small or your creative is rated low quality. If CTR and conversion rate rise with it, CPA may not be worse.
Which matters more, CPM or CPC?
Both are intermediate numbers; CPA and ROAS are what you protect. CPC = CPM ÷ (CTR × 1,000), so CPM only tells you whether clicks are dear when read with CTR.
Where the course puts it to work
- Intermediate, chapter 6: Reading ad data: the four formulas behind the report
- Advanced, chapter 11: When results drop: a diagnosis sequence and the weekly report
Official sources
We read each page below on 2026-10-23 and built the definition from it.
- CPM (Cost per 1,000 Impressions) · Checked 2026-10-23
- Impressions · Checked 2026-10-23
- Cost-per-thousand impressions (CPM): Definition · Checked 2026-10-23
- About Ads Metrics in Seller Center · Checked 2026-10-23