CPM (cost per mille)
CPM is the price of being seen. In Apple Ads it is either what you actually bid and pay on impression-priced placements, or an effective figure that translates tap-priced spend into a cost per thousand views.
Updated
Mille is Latin for thousand, so cost per mille is the cost of one thousand impressions. It is one of the oldest pricing units in advertising, and across mobile ad networks it is the standard way to buy reach for display and video ads. In Apple Ads it plays two roles, and mixing them up is the most common source of confusion about the metric.
How CPM is calculated
Adapty Ads Manager reports average CPM for any campaign, ad group or keyword as spend divided by thousands of impressions over the reporting period.
The same spend can be read through CPM or CPT. If those 60,000 impressions produced 4,800 taps, the average CPT was $0.1875 and the tap-through rate was 8%. CPM equals CPT multiplied by TTR and by 1,000, which is why a rising CPM on a tap-priced campaign can mean either more expensive taps or more taps per impression.
CPM-priced and CPT-priced placements
Apple Ads does not sell every placement the same way. Search results campaigns, the ones that target keywords, are priced per tap. Some placements that build awareness rather than answer a search, such as the Today tab, are priced per thousand impressions, so you bid a maximum CPM and pay for views whether or not anyone taps.
- On CPM-priced placements, CPM is the price you control directly with your bid. Watch TTR and downloads alongside it, because impressions alone earn nothing.
- On CPT-priced search results campaigns, the CPM in your report is effective CPM: spend converted to a per-thousand-impressions rate after the fact. You never bid it.
- Effective CPM lets you compare the cost of visibility across placements with different pricing models on one scale.
When CPM is worth watching
For keyword campaigns, CPT, conversion rate and downstream subscription metrics usually explain performance better than CPM. CPM becomes useful in three situations.
- Budgeting impression-priced placements. The CPM you pay sets how much reach a budget buys, so it is the first number to check when a Today tab campaign underdelivers or overspends.
- Comparing placements. Effective CPM puts search results next to impression-priced placements, so you can see the cost of reach in each before comparing the subscribers each one brings in.
- Reading downloads per thousand impressions. Pairing CPM with DPM, downloads per mille, gives a quick sense of how efficiently a thousand impressions turn into downloads for a given price.
CPM and subscription economics
For a subscription app, a cheap thousand impressions only matters if some of the people who saw the ad start a trial, convert and renew. The useful question is what a thousand impressions eventually earns. Put CPM next to cost per trial, cost per subscription and cohort ROAS for the same campaign, and judge the placement on payback rather than on the price of reach.
Related metrics: CPT for the price of a tap, TTR for how often impressions become taps, DPM for downloads per thousand impressions, and CPA for the cost of each download.