A patio and outdoor kitchen contractor in Westfield forwarded me his Google Ads dashboard last week. His reported return on ad spend had jumped 30 percent between two Mondays. He hadn't touched a bid or a dollar of budget between them.

The jump came from a setting he had never opened.

Google Analytics now lets you set a custom conversion lookback window, from 1 day up to 90, on every Google Ads account connected to it. Stretch that window and more sales get credited to your ads, whether the ad had anything to do with the sale or not. Your reported numbers improve. Nothing else does.

What is a conversion lookback window?

A lookback window (Google also calls it an attribution or conversion window) answers one question: if someone clicks your ad on a Tuesday and buys from you three weeks later, does that sale count as coming from the ad?

Set the window to 7 days and the answer is no. The sale shows up as organic, or direct, or from whatever channel closed it. Set the window to 90 days and the answer is yes. The ad gets the credit, and your reported ROAS goes up, even if the customer would have bought from you anyway.

There's a second version of the same dial for video ads: the engaged-view conversion window. It covers someone who watched your video ad without clicking it, then bought later. Until this month, Google locked that window at a fixed 3 days for every advertiser on Analytics, with no exceptions.

What did Google change on August 11?

Google's release notes, dated August 11, 2026, describe the update plainly: click-through and engaged-view conversion windows both accept a custom whole number of days now, instead of a short list of presets.

Window type	Before	After
Click-through conversion	Six presets: 1, 7, 14, 30, 60, or 90 days	Any whole number, 1 to 90 days
Engaged-view conversion (video ads)	Fixed at 3 days, no adjustment	Any whole number, 1 to 30 days

The setting lives in Google Analytics under Advertising, then Conversion management, then Settings, and it's reachable from the linked Google Ads conversion management screen too. Google's own documentation confirms the change applies going forward and shows up in every report tied to that property, including how credit gets split between channels in the first place.

Google shipped this without a blog post or a press release. It landed as three lines in a release-notes changelog most advertisers never read.

Why does a longer window inflate your ROAS?

Two Indianapolis-area shops show why this matters.

The Westfield contractor sells patios and outdoor kitchens. A real customer might see three of his ads, get a quote from a competitor, and sign a contract six weeks later. A 60 or 90 day window is honest for him. It reflects how long people take to decide.

A boutique spin studio in Carmel runs the opposite kind of business. Someone sees a Reels ad for a free trial class, and either signs up that week or forgets about it entirely. If the studio's owner sets her engaged-view window to the new 30-day maximum, she starts crediting the ad for people who found the studio through a friend or a Google search, three weeks after the ad played. None of those sign-ups came from the ad. They'll show up as if they did.

Most shops running Google Ads have never opened this setting, and it decides how good their numbers get to look.

The wider the window, the more of your organic and repeat business gets relabeled as ad performance.

What should you set yours to?

Three moves, in order.

First, find your current setting. In Google Ads, open a conversion action and check its attribution window under Settings. In Google Analytics, go to Admin, then Conversion management, then the settings icon next to each key event.

Second, time your real sales cycle. Pull your last 20 sales and note how many days passed between the customer's first contact and the sale. A dry cleaner or coffee shop should see numbers under a week. A contractor or a wedding photographer should see four to eight weeks. Set your window close to that number. Don't set it to whichever preset made last month's report look best.

Third, if your ROAS moves and you haven't touched a bid or your creative, check this setting before you touch anything else. A ROAS increase built on a wider window falls the moment you hit a slow month, because the window was never counting new customers. It was counting a longer stretch of customers you already had.

We set these windows correctly on every ad account we manage. A ROAS number built on the wrong window is worse than no number, because you'll trust it.

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Sources

| Source | What it backed up

---|---|--- 1 | Change the key event lookback window | Confirms the window applies going forward to all reports, including session attribution, and explains what the window controls. 2 | What's new in Google Analytics | Google's own August 11, 2026 release note announcing custom lookback windows for click-through and engaged-view conversions. 3 | Google Analytics drops the fixed 3-day engaged-view conversion window | Independent confirmation of the prior fixed 3-day engaged-view window and the new 1 to 30 day range. 4 | Google Analytics adds custom conversion attribution windows | Reporting on the practical impact for advertisers managing Google Ads accounts linked to Analytics.