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All creative types use
delayed impressions.
This means that impressions aren't counted until the creative renders and
sends an impression request back to Google. Because of this secondary request,
RTB breakout and
RTB Troubleshooting
can return a greater number of winning bids than billable impressions.
Expiration windows
The expiration window for impressions-based billing events varies by inventory
type. The expiration window of the request in seconds is sent in the
BidRequest.imp.exp field.
[null,null,["Last updated 2025-08-18 UTC."],[[["\u003cp\u003eAll creative types use delayed impressions, meaning impressions are only counted after the creative renders and sends a request back to Google.\u003c/p\u003e\n"],["\u003cp\u003eThis delayed impression process can lead to a discrepancy between winning bids and billable impressions, especially in Real-Time Bidding (RTB) scenarios.\u003c/p\u003e\n"],["\u003cp\u003eImpression billing has varying expiration windows depending on the inventory type: App Open, server-side, and podded in-stream video requests have a 4-6 hour window, while all other inventory has a 1-hour window.\u003c/p\u003e\n"]]],[],null,["# Impressions expiration\n\nAll creative types use\n[delayed impressions](//support.google.com/admanager/answer/2521337).\nThis means that impressions aren't counted until the creative renders and\nsends an impression request back to Google. Because of this secondary request,\n[RTB breakout](//support.google.com/authorizedbuyers/answer/6156706) and\n[RTB Troubleshooting](/authorized-buyers/apis/guides/v2/rtb-troubleshooting)\ncan return a greater number of winning bids than billable impressions.\n\nExpiration windows\n------------------\n\nThe expiration window for impressions-based billing events varies by inventory\ntype. The expiration window of the request in seconds is sent in the\n`BidRequest.imp.exp` field.\n| **Important:** Google records and bills for all impressions received within the following time periods. \\* [App Open](//support.google.com/admanager/answer/9351867) requests: 4 hours \\* [Server-side](//support.google.com/admanager/answer/6147120) requests: 4-6 hours \\* [Podded in-stream](//support.google.com/admanager/answer/2554762) video inventory: 4-6 hours \\* All other inventory: 1 hour"]]
