Introduction to Unity Ads User Acquisition bids
When you run a user acquisition campaign, your campaign makes bids to place your ad in other apps. These user acquisition bids determine how much of your campaign budget you spend to get impressions.
Bid terminology
Review the following user acquisition bidding terms used in this documentation.
| Bid term | Acronym | Definition |
|---|---|---|
| Effective cost per thousand impressions | eCPM | The calculated cost of one thousand impressions, based on the video conversion rate and cost per install |
| Video conversion rate | CVR | The rate at which users who view your ad install your app |
| Cost per install | CPI | The amount of your campaign budget spent to acquire an install |
| Cost per mille (per impression) | CPM | The average cost of one thousand impressions |
| Target cost per install | tCPM | The dynamic cost of one thousand impressions, based on the expected video conversion rate. |
Unity Ads is a bidding platform. The exposure of your ad campaign depends on its eCPM (effective cost per thousand impressions), which is determined by the CVR (video conversion rate from impression to install) and CPI (cost per install) of your campaign. The higher your campaign’s eCPM, the more exposure it receives.
Unity User Acquisition provides a variety of bidding strategies to match your campaign goals:
| Campaign goal | Bidding strategy |
|---|---|
| Installs | Cost per impression (CPI) bids for Android install campaigns Target cost per install (tCPI) bids for iOS campaigns |
| Retention | Dynamic automated bidding based on: Base bids Max bids |
| Revenue | Dynamic automated bidding based on ROAS targets |
| Event engagement | Cost per event (CPE) bids |
Install bids
The following sections decribe the different ways install bids work depending on your campaign type.
CPI versus tCPI bidding for install campaigns
While the goal of install campaigns is always to net the most app installs possible, Android and iOS install campaigns use different bidding models because they follow different billing models.
Android CPI bids
Android campaigns use cost per install, or CPI billing. CPI is a pricing model that bills advertisers the specified bid price each time an install is attributed to their campaign. As such, the advertiser pays the exact bid price when an attributed install occurs.
iOS tCPI bids
iOS campaigns use cost per impression, or CPM billing. CPM is a pricing model that bills advertisers based on the number of impressions their campaign receives. As such, iOS campaigns use target cost per install, or tCPI bidding. The advertiser sets the desired amount to pay per install, which Unity optimizes towards based on eCPMs and creative performance.
Unity’s tCPI model differs slightly from traditional industry CPM models. In a traditional industry CPM campaign, you pay a predefined amount per thousand impressions (cost per mille, or CPM) that your ad receives. In this model, you serve ads to anyone matching your campaign’s targeting criteria, and you pay the same amount for each impression.
Unity serves ads to users who are most likely to install your app. You pay a dynamic price depending on the potential value of the player. The price is tied to the probability that the impression will convert to an install. Using this model, Unity targets impressions that are likely to translate to your target CPI.