Enter spend and impressions to get cost per thousand, or set a target CPM to find the budget.
CPM prices attention in blocks of a thousand. It is the standard unit for display, video and social buying, because that inventory is sold on reach rather than response.
Two things trip people up. An impression is a served ad, not a seen ad, viewability is measured separately and typically lands between 50 and 70 percent, which means your effective cost per viewed impression is often double the CPM you paid. And a low CPM is not automatically good: cheap inventory is cheap because demand for it is low. A $2 CPM that reaches nobody relevant costs more per outcome than a $30 CPM that does.
CPM is what you agreed to pay per thousand impressions. eCPM is what a thousand impressions earned or cost after the fact, used to compare buys priced on different models, a CPC campaign has an eCPM even though nobody bid on impressions. vCPM charges only for impressions that met a viewability standard, usually 50 percent of pixels in view for one second on display, two seconds on video.
If you are comparing a CPC search campaign against a CPM display campaign, convert both to eCPM first. Otherwise you are comparing prices for different things.
| Channel | Typical CPM |
|---|---|
| Google Display Network | $2–8 |
| Meta, Facebook and Instagram | $7–18 |
| YouTube in-stream | $9–25 |
| TikTok | $6–14 |
| $25–70 | |
| Connected TV | $25–55 |
| Programmatic open exchange | $1–5 |
If the campaign has a conversion goal, CPM tells you almost nothing. You can halve CPM by moving to worse placements and watch every downstream number get worse at the same time.
CPM earns its place in two situations: buying reach for an awareness campaign where there is no click to measure, and diagnosing why a CPC rose. If cost per click jumped and CPM is flat, the problem is click-through rate, the creative. If CPM jumped and CTR is flat, the problem is auction pressure, competitors, seasonality or a narrower audience.
CPM is the start of a chain, and every link after it multiplies. What a customer finally costs depends on the media price and on two rates that CPM says nothing about.
| CPM | CTR | Conversion rate | CPA |
|---|---|---|---|
| $5.95 | 1.0% | 3% | $19.83 |
| $5.95 | 0.5% | 3% | $39.67 |
| $11.90 | 1.0% | 3% | $39.67 |
| $11.90 | 2.0% | 3% | $19.83 |
The table makes the point directly. A campaign paying double the CPM reaches exactly the same CPA if its CTR is twice as high. Cheap impressions are only cheap if people act on them. Link the rest of the chain with the CTR calculator and the CPA calculator.
Chasing low CPM is the media equivalent of buying the cheapest seats and complaining about the view. The lowest prices come from the least contested inventory: broad audiences, low-attention placements, partner networks and the bottom of long pages. The impressions are cheap because advertisers who measure outcomes have learned not to want them.
The second trap is reading a CPM rise as a failure. CPMs climb every fourth quarter as retail budgets flood the auctions, and they climb when you narrow targeting toward people more likely to buy. A higher CPM that reaches a better audience often produces a lower cost per sale.
The third is comparing CPM across platforms as if an impression were a fixed unit. A skippable video view, a feed impression and a display banner below the fold all count as one impression. They are not worth the same, and a lower number on one platform does not mean better value.
Common causes are seasonal competition, especially in the fourth quarter, narrower targeting, lower ad relevance, and more advertisers bidding on the same audience. A rising CPM is only a problem if cost per acquisition rises with it.
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