CPM, CPC, CPI, CPA and eCPM: Mobile Ad Pricing Models Explained

Mobile advertising is bought and sold in a handful of units: per thousand impressions, per click, per install, per action. Each unit has an abbreviation, and the abbreviations get used loosely enough that two people in the same meeting can mean different things by eCPM. This guide defines each one, gives the formula, and then shows the relationship that matters most to anyone making ads: how impressions, installs and price connect, and why a better creative works exactly like a bigger budget.

The pricing models

CPM: cost per mille

The price of a thousand impressions. Mille is Latin for thousand. CPM = cost / impressions x 1,000. Spending 500 on 200,000 impressions is a CPM of 2.50. CPM is how most auctions price inventory underneath, even when the advertiser is billed on something else, and it is how Meta and TikTok usually charge by default, even when the campaign is optimised for installs.

eCPM: effective cost per mille

The CPM a campaign or an ad slot effectively produced, whatever unit it was actually bought or sold in. The formula is the same, eCPM = money / impressions x 1,000, but which money depends on the side of the market. For a publisher, eCPM is ad revenue per thousand impressions, and it is the number game developers use to compare ad networks in their mediation. For an ad network, a campaign's eCPM is what it would earn per thousand impressions by showing that campaign, and it is how the network decides which ad wins.

CPC: cost per click

The price of one click or tap. CPC = cost / clicks. Common in search and web advertising. Apple Ads search placements use a version of it called cost per tap. In app install advertising CPC matters less than what happens after the click, because a click that does not become an install is worth nothing.

CPI: cost per install

The price of one install. CPI = cost / installs. Many in-app ad networks let advertisers bid on CPI directly, and every user acquisition team reports it, whatever they were billed in. It is the most quoted number in mobile games and the most misleading one on its own, because it says nothing about whether the player stays.

CPA, CPE and value-based bidding

CPA, cost per action, prices something after the install: a registration, a tutorial completed, a first purchase. CPE, cost per engagement, is the same idea for a specific in-app event, or in brand advertising for an interaction with the ad. Most networks now also offer bidding on value, where the advertiser sets a target return on ad spend and the network buys the players it predicts will be worth the most. These models move the bid closer to what the advertiser actually wants, at the cost of fewer conversions to learn from.

CPV and CPCV

Cost per view and cost per completed view, used for video, mostly in brand campaigns. What counts as a view differs by platform, so compare them only within one platform.

The performance ratios

• CTR, click-through rate: clicks / impressions. How often the ad gets a tap.
• CVR, conversion rate: installs / clicks. How often a tap becomes an install. Mostly a measure of the store page and of whether the ad set honest expectations.
• IPM, installs per mille: installs / impressions x 1,000. How many installs every thousand impressions produce. It combines CTR and CVR into one number, and it is the single best measure of a creative's pulling power.
• ROAS, return on ad spend: revenue from the acquired players / spend, usually measured at day 7, 30 or later. The number that decides whether the whole thing pays.

How the numbers connect

One identity ties everything together. Since CPM is cost per thousand impressions and IPM is installs per thousand impressions, dividing one by the other gives cost per install:

An illustration with round numbers, not a benchmark: if impressions cost 10 per thousand and a creative produces 5 installs per thousand, each install costs 2. If a better creative produces 10 installs per thousand at the same CPM, each install costs 1. Nothing about the bid, the targeting or the budget changed; only the ad did.

Why a better creative works like a higher bid

Turn the identity round and look at it from the network's side. When an advertiser bids on CPI, the network does not earn anything from an impression unless it produces an install. So to rank competing ads for an impression, the network estimates each one's eCPM: the CPI bid multiplied by the predicted installs per impression. Two advertisers bidding the same CPI do not compete equally: the one whose creative converts twice as often is worth twice as much per impression to the network and wins the auction.

That is the arithmetic behind the claim that creative is the main lever in user acquisition. Doubling IPM has the same effect on delivery as doubling the bid, except that the advertiser pays the same price per install instead of twice as much. It is also why a new creative with no history often gets few impressions at first: the network has no IPM estimate yet and has to spend impressions finding one. Why a playable gets no impressions covers that learning phase.

Which networks use which model

• In-app ad networks such as Unity Ads, AppLovin, Mintegral and Liftoff commonly offer CPI bids, event bids and ROAS targets, ranking ads internally by expected eCPM.
• Social platforms such as Meta and TikTok usually charge per impression and optimise delivery toward the install, event or value the advertiser picks.
• Google App campaigns are set with a target cost per install, cost per action or ROAS, and Google chooses placements across Search, Play, YouTube and its partners.
• Apple Ads bills search placements per tap. See Apple Ads for mobile games.

Mistakes these numbers invite

• Comparing CPM across platforms. A thousand impressions in a full-screen rewarded slot and a thousand in a scrolling feed are not the same product.
• Optimising CPI alone. The cheapest installs often come from players who leave on day one; judge creatives on early retention and ROAS too. How to lower CPI covers doing it without buying worse users.
• Comparing IPM across placements. Rewarded placements usually produce more installs per thousand than interstitials; compare creatives within one placement.
• Reading eCPM from the wrong side. A publisher's eCPM is revenue; an advertiser's is cost. Say which.

Playables earn their place in this arithmetic because they tend to raise IPM: a viewer who has already played the core loop arrives in the store knowing what the game is. Playable Ads Maker builds one project and exports it in the format each of 13 ad networks asks for, so the same creative can be measured on IPM across every network you buy from.