Attribution windows explained (and how they change your numbers)

What an attribution window is

When someone clicks your ad, the ad platform starts a clock. If that person buys before the clock runs out, the platform counts a conversion for the ad. If they buy after, the ad gets no credit. That stretch of time is the attribution window, also called a conversion window or lookback window.

There are usually separate clocks for different kinds of contact. A click window covers people who clicked. A view window covers people who only saw the ad. Some platforms add an engaged-view window for people who watched a video ad for a while without clicking.

The default windows on major platforms

Defaults matter because most advertisers never change them. As of October 2026, the platforms' own documentation says:

• Google Ads: a new conversion action uses a 30-day click window, a 3-day engaged-view window and a 1-day view-through window unless you change them, according to Google's conversion window guide. The overall range runs from 1 to 90 days depending on the conversion source.
• Google Analytics 4: the default lookback window is 90 days for most key events and 30 days for first visits and first app opens. You can shorten either.
• Meta: its reporting documentation lists the default as 7 days after a click and 1 day after a view.
• TikTok: ad group attribution settings let you choose a click window of 1, 7, 14 or 28 days and a view window of Off, 1 or 7 days.

How the window changes your numbers

Imagine a furniture store whose buyers usually take two or three weeks to decide. Under a 7-day click window, many of those sales fall outside the window and the ads look weak. Under a 30-day window, the same sales are credited and the ads look strong. Nothing about the ads changed, only the counting rule. If the owner compared the two reports without knowing the windows differed, they might cut a campaign that was actually paying for itself.

The reverse problem hits stores with quick, cheap purchases. A long window sweeps in repeat buyers who would have come back anyway, so ads collect credit for loyalty they didn't create.

Windows also drive double counting. If Google looks back 30 days and Meta looks back 7, a buyer who touched both inside those periods gets claimed twice. Our article on why ad platforms claim more sales than you made explains that overlap, and view-through conversions explained covers the view window in detail.

Why yesterday always looks bad

Conversions are usually reported back to the day of the click, not the day of the sale. Google notes in its conversion delay guide that conversions can be reported up to 90 days after the click, depending on your window.

So the last few days in any report are incomplete. A campaign that seems to have collapsed this week may simply be waiting for buyers who are still deciding. Before pausing anything, compare recent days with how the same days looked a week or two later in past months.

Choosing the right window

Start with your own sales data. Look at how long customers typically take between first visit and purchase, then follow these rules of thumb:

Matrix ROI, developed by Smith App Studio, shows each platform's claimed conversions day by day beside your verified payments, which makes window-driven gaps easy to spot. The live demo has sample data you can explore.

• Set the click window a little longer than your typical decision time, not far longer.
• Keep view windows short, usually 1 day, unless a test proves longer views drive real sales.
• Use the same window when comparing platforms, even if that means changing one platform's report settings.
• Write down your window choices. When someone changes a setting, past and present numbers stop being comparable.
• Check totals against real revenue. If credited sales far exceed what landed in your account, your windows are too generous.