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Bidding overview

Updated: Jun 28, 2026

A bid expresses how much you value your ad reaching a target audience and delivering results on your optimization_goal. bid_amount is the amount you want to spend to acquire a given event based on optimization_goal, and bid_strategy is how you want to control your spend on a given event based on optimization_goal.

In the Facebook ad auction, Facebook evaluates your bid_strategy, bid_amount, and the probability of acquiring your optimization_goal to calculate an effective bid so that you only win auctions and have your ads delivered when you are likely to reach your optimization_goal within certain bidding constraints such as cost per result.

Meta consolidated the Reach and Impressions optimizations into a single optimization.

In the API, selecting the Reach optimization will return the value of "Impressions" in optimization_goal and with the advertiser's frequency control setting.

Bidding and Optimization core concepts include:

Bid setup

When you choose your bid:

  • Set bid_amount to the maximum amount you're willing to pay for your advertising objective.
  • Decide whether to optimize for return on ad spend or for the number of results.

You can also set objective and billing_event but neither directly impacts bid_amount or your effective bid. If a bid_amount is set, your actual cost per result is usually around or less than bid_amount, depending on your Bid Strategies.

For example, use these settings to spend about $10.00 for 1,000 daily unique views:

  • Campaign objective: APP_INSTALLS
  • Ad set optimization_goal: REACH
  • Ad set billing_event: IMPRESSIONS

However, to spend $10.00 for each app install, use these settings:

  • Campaign objective: APP_INSTALLS
  • Ad set optimization_goal: APP_INSTALLS
  • Ad set billing_event: IMPRESSIONS

Optimization goals

Define advertising goals you want to achieve when Facebook delivers your ads. Facebook uses your ad set's optimization_goal to decide which people get your ad. For example with APP_INSTALLS, Facebook delivers your ad to people who are more likely to install your app.

optimization_goal defaults to a goal associated with your objective. For example, if objective is APP_INSTALLS, optimization_goal defaults to APP_INSTALLS.

Validation

These older objectives are deprecated with the release of Marketing API v17.0. Please refer to the Outcome-Driven Ads Experiences mapping table to find the new objectives and their corresponding destination types, optimization goals and promoted objects.

Certain campaign objectives support only certain ad set optimization_goals:

Campaign objectiveDefault optimization\_goalOther valid optimization\_goal
APP_INSTALLS, promoting an Instant Experiences appAPP_INSTALLSIMPRESSIONS, POST_ENGAGEMENT
APP_INSTALLS, promoting a mobile appAPP_INSTALLSOFFSITE_CONVERSIONS, LINK_CLICKS, REACH and VALUE
BRAND_AWARENESSAD_RECALL_LIFTREACH
CONVERSIONSOFFSITE_CONVERSIONSIMPRESSIONS, LINK_CLICKS, POST_ENGAGEMENT, REACH, VALUE, LANDING_PAGE_VIEWS, and CONVERSATIONS
EVENT_RESPONSES, promoting an eventEVENT_RESPONSESIMPRESSIONS, REACH
EVENT_RESPONSES, promoting a Page postEVENT_RESPONSESIMPRESSIONS, POST_ENGAGEMENT, REACH
LEAD_GENERATIONLEAD_GENERATIONQUALITY_LEAD, LINK_CLICKS, and QUALITY_CALL
LINK_CLICKSLINK_CLICKSIMPRESSIONS, POST_ENGAGEMENT, REACH, LANDING_PAGE_VIEWS
LINK_CLICKS, promoting an Instant Experiences appENGAGED_USERSAPP_INSTALLS, IMPRESSIONS, POST_ENGAGEMENT, REACH
LINK_CLICKS, promoting a mobile appLINK_CLICKSIMPRESSIONS, REACH, OFFSITE_CONVERSIONS
MESSAGESCONVERSATIONSIMPRESSIONS, POST_ENGAGEMENT, LEAD_GENERATION, and LINK_CLICKS
PAGE_LIKESPAGE_LIKESIMPRESSIONS, POST_ENGAGEMENT, REACH
POST_ENGAGEMENTPOST_ENGAGEMENTIMPRESSIONS, REACH, and LINK_CLICKS
PRODUCT_CATALOG_SALESOFFSITE_CONVERSIONS or LINK_CLICKSIMPRESSIONS, POST_ENGAGEMENT, REACH, CONVERSATIONS, and VALUE
REACHREACHIMPRESSIONS
VIDEO_VIEWSTHRUPLAY

FAQ

The following answers address common questions about bidding and optimization goals.

What events does 'POST_ENGAGEMENT' cover?

Most actions in an ad, including link clicks, app installs, video viewing over a certain period, tag photo, like, comment, share, and so on.

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