Google AdSense and Ad Manager Switch to Begin-to-Render Impression Measurement in February 2027
Google will change how it counts display ad impressions across AdSense and Google Ad Manager starting February 17, 2027, moving from the current count-on-download methodology to the begin-to-render standard that the industry has increasingly adopted.
What was announced
Google sent emails to publishers on September 1, 2026, notifying them that impression measurement for display inventory will switch from count-on-download (COD) to begin-to-render (BTR) methodology. The change affects both AdSense and Ad Manager accounts and applies to display banner ads on mobile web, desktop, and connected TV (CTV) inventory.
What changed
Under the current count-on-download approach, Google counts an impression when an ad starts to download to a user's device. Beginning February 17, 2027, an impression will only be counted once the ad creative has successfully loaded and has started to render on the user's device.
The shift means that ads that began downloading but never actually rendered—such as when a user leaves the page before the ad appears—will no longer be counted as impressions.
Google already uses or complies with begin-to-render for native, app, and video inventory. The upcoming change extends BTR to display banner ads, unifying impression counting methodologies across all inventory types.
Details and availability
Effective date: February 17, 2027
Affected inventory:
- Display banner ads on mobile web
- Display banner ads on desktop
- Display banner ads on connected TV (CTV)
Not affected:
- Non-banner display (native, interstitial) — already BTR compliant
- App inventory — already using 1-pixel method (BTR compliant)
- Video inventory — already using first-frame method (BTR compliant)
Action required: None. Google stated that no action is required from publishers. The transition will happen automatically.
Context
Begin-to-render is the industry standard and preferred methodology for impression counting, according to the Interactive Advertising Bureau (IAB) desktop display measurement guidelines. BTR presents a greater likelihood that the user can actually view the ad, compared to count-on-download which counts impressions even for ads that may never appear on screen.
The change aligns Google's impression measurement with demand-side platforms and streamlines publisher workflows by eliminating the need to buffer COD campaigns to deliver against BTR terms used by other platforms.
What has not been confirmed
Google has not specified the expected magnitude of the impression count decrease after the transition. The actual impact will depend on how many ad downloads currently fail to render before appearing on users' devices.
Google has not detailed whether this change will affect CPM rates, total revenue, or how advertisers will be billed during and after the transition period.
The announcement does not clarify whether historical impression data will be restated to reflect BTR methodology, or whether publishers will see a clean break in reporting starting February 17, 2027.
