From 17 February 2027, Google Ad Manager and AdSense will only count a web display impression once the ad has actually started to appear on screen. It sounds like a small technical tweak, but it will change the numbers in your reports and could affect how you read your revenue.
You don’t need to do anything today. But there’s plenty you can do over the next four months to make sure the switch is a non-event for your business, rather than a nasty surprise in your February reporting. Here’s what’s changing, what it means for your numbers and how to get ready.
What’s changing
Today, Google counts display impressions using count-on-download (COD). An impression is recorded as soon as the ad starts downloading to the user’s device, even if it never makes it onto the screen.
From 17 February 2027, Google moves to begin-to-render (BTR). An impression only counts once the creative has loaded and started to render. If a reader scrolls past or leaves the page before the ad starts drawing, that impression no longer counts.
Before 17 Feb 2027: Count-on-download — an impression counts when the ad starts downloading.
From 17 Feb 2027: Begin-to-render — an impression counts when the ad starts rendering on screen.
Inventory covered: Display banners on desktop, mobile web and CTV; the same inventory remains covered after the change.
Native, app and video impressions in Ad Manager already use begin-to-render, so this change brings web display into line with everything else. It also matches how DSPs and third-party measurement vendors already count, which is why Google describes BTR as the industry standard.
What it means for your numbers
Reported impressions will probably fall. Google itself expects reported display impression volumes to drop. Ads that downloaded but never rendered simply won’t be counted any more. How big the drop is depends on your site: pages that load slowly, or where readers bounce quickly, will see the biggest gap.
That isn’t the same as losing revenue. Most of your demand already buys and bills on a rendered or viewable basis, so the impressions disappearing from your reports are largely ones advertisers weren’t valuing anyway. You may well see fewer impressions at a higher eCPM, with total revenue broadly steady.
Your benchmarks will shift. Year-on-year and month-on-month comparisons that cross 17 February will be distorted, and fill rate, sell-through, RPM and eCPM trends will all move. It’s worth flagging this now to anyone who reads your ad reports, so a February dip in impressions isn’t mistaken for a traffic or demand problem.
Discrepancies should shrink. Because Google will count the same way DSPs and third-party verification tools already do, the gaps between your Ad Manager numbers and your buyers’ numbers should narrow. That makes campaign reconciliation and makegoods simpler.
How to prepare before February
- Measure your gap now. Google recommends that Ad Manager publishers compare their current impression counts against begin-to-render metrics, so you can estimate the drop before it happens rather than after.
- Speed up time-to-render. Every ad that renders before a reader moves on is an impression you keep. Look at your Core Web Vitals, how early your ad scripts load and any heavy third-party tags slowing the page down.
- Check your lazy-loading. Lazy-loading helps viewability, but if it’s set too tight, ads can start downloading and never get the chance to render. Review your fetch and render margins, especially on mobile.
- Review refresh and sticky units. Units that refresh aggressively, or adhesion slots that request ads a reader never sees, are the most likely to lose counted impressions.
- Reset expectations internally. Let your finance, sales and editorial teams know now that February reporting will change, and agree which metrics you’ll judge performance on (revenue and RPM rather than raw impressions).
- Update your direct deals. If you sell guaranteed campaigns on impression volume, check how any contracts running past 17 February define an impression.
How Content Ignite is helping
We’re already preparing for the switch across our publisher network. Our team is reviewing ad stack configurations, lazy-load settings and refresh rules to make sure ads get the chance to render, so you keep as many counted impressions as possible.
We’ll also help you read your numbers through the transition. That means focusing on revenue and RPM rather than raw impression volume, and clearly flagging in your reporting where the methodology change starts.
If you’d like us to review your setup ahead of February, or want to understand how the change could affect your site, get in touch with your Content Ignite account manager. We’d much rather talk about it now than explain a dip in March.
Sources: Google Ad Manager Help, “Begin-to-render impression counting for display ads”; Google Authorized Buyers Help.
