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Introduction to CPI bidding

Learn about how bidding works for Cost per Install (CPI) campaigns with Unity User Acquisition
Read time 2 minutesLast updated 9 hours ago
Unity supports two different types of Cost per Install (CPI) bids: manual and automated. Refer to the following sections for descriptions of these bid types.

Manual bids

Use a manual bidding strategy to set a static CPI bid that you want to pay per install throughout the day. The system tries to optimize the bids to achieve an average CPI. This means that sometimes the CPI can be higher or lower than the bid amount.

Automated bids

Automated CPI bidding automatically manages and spends your daily budget. This strategy maximizes installs for budget-constrained campaigns and optimizes budget usage throughout the day. Instead of always using the maximum specified CPI bid, automated bidding controls spending and optimizes budget usage by focusing on opportunities with a high predicted value. Automated campaigns bid dynamically by discounting the maximum bid according to a machine learning algorithm. If the maximum CPI bid is restrictive enough that the campaign can't spend its daily budget, thereby limiting campaign delivery, then Unity doesn't discount the bid and the automated campaign effectively uses a manual, static CPI bidding strategy. For example, assume the following:
  • Your campaign wins an impression if it bids $0.01 or more.
  • Your campaign has a daily budget of $1.
  • Your campaign has a CPI bid of $1.
  • Your campaign observes 300 opportunities throughout the day.
  • The first 100 opportunities have a predicted conversion rate of 1%.
  • The next 200 opportunities have a predicted conversion rate of 2%.
With a CPI bid of $1, the example campaign will run out of money after the first 100 impressions, because a 1% conversion rate yields one install. If you instead lower the bid by a fixed 50% and bid $0.50, the example campaign loses the first 100 opportunities but wins the latter 200 opportunities and yield 2 installs for the same cost. To use the Automated Bidding strategy, add the maximum bids for each country you target with the campaign and the system will automatically optimize delivery against your max bids. Use this strategy to control the maximum that you're willing to pay per install, knowing that the actual price will be somewhere between zero and the max bid. The recommended best practice is to set high maximum bids even with small budgets. Automated Bidding dynamically discounts the actual bids to help you win impressions and meet your campaign goals.
Note
The recommended best practice is to create a separate campaign for each tier of countries, or use country-level daily caps to optimize performance in countries with different price levels.
Automated Bidding requires a daily cap. The recommended best practice is to use the following parameters:

Parameter

Minimum Value

Daily cap$50
Campaign budget$500
Campaign durationOne week
Note
CPM billing for Automated bidding is a beta release. Features and documentation might change between now and the next release.