What you pay per 1,000 impressions - the price of attention in the ad auction. You do not set your CPM directly: it reflects how competitive the auction is and how well users respond to your creative. That second part is what founders miss. Rising CPMs with flat results are almost never a platform problem, they are a creative problem - the algorithm charges you more when your ads stop earning attention. Accounts running fewer than four creatives fatigue fastest, paying 20-30% higher CPMs within two weeks, which is why creative volume is the real CPM lever.
Benchmark. On Meta, $10-30 is typical, $30+ in competitive verticals like beauty, health and supplements. The absolute number matters less than the trend: a sharp rise against your own baseline signals audience compression or creative fatigue - rotate before it compounds.