CPM (Cost Per Mille)
CPM is the price advertisers pay per 1,000 ad impressions, one of the core metrics in paid traffic buying. Ad platforms calculate it as spend divided by impressions, multiplied by 1,000. On its own, CPM is not a profit metric — it's the entry cost of reach that still has to convert into clicks and installs.
How CPM is calculated and what moves it
The formula is straightforward: CPM = (spend / impressions) x 1000. Price depends on geo, vertical, audience competition, and ad account quality — broader, colder audiences tend to bid lower. Tier-1 geos almost always carry a higher CPM than Tier-3 simply because more advertisers compete for the same eyeballs.
CPM in PWA arbitrage
CPM only covers the top of the funnel — CTR on the creative and the PWA landing's conversion rate to install decide the real cost. A cheap CPM with weak CTR often ends up pricier than an expensive CPM paired with a strong creative, so sources should be compared on final CPI, not CPM alone. APEX split-tests with sticky visitor bucketing help find the creative-plus-prelander combo that turns the same CPM spend into a cheaper install.
FAQ
- How is CPM different from CPC?
- CPM charges for impressions regardless of clicks, while CPC only charges for an actual click-through. A weak creative with low CTR makes CPM the more expensive model; a strong creative often makes it cheaper than CPC.
- What counts as a good CPM in PWA arbitrage?
- There's no universal number — rates swing heavily by geo and vertical. Judge sources by final CPI and ROI after impressions convert into installs, not by CPM alone.
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