What is an attribution window?
An attribution window is how long after a click or view a conversion can still be credited to an ad. Here are the Google Ads, GA4 and Meta defaults, the 2026 Meta changes, a worked example and how to choose yours.
An attribution window, also called a lookback or conversion window, is the period after someone clicks or views an ad during which a conversion can still be credited to that ad. With a 7-day click window, a purchase eight days after the click is not attributed to it. The window changes reported conversions, never actual sales.
How do attribution windows work?
Most platforms run separate clocks for clicks and views. A conversion is credited only if it falls inside the window that matches the interaction. Defaults differ by platform:
| Platform | Default window | Notes |
|---|---|---|
| Google Ads | 30-day click, 1-day view | Click window adjustable, up to 90 days |
| GA4 | 90 days | 30 days for first_visit and first_open |
| Meta Ads | 7-day click, 1-day view | 7-day and 28-day view removed from the API in 2026 |
Sources: Google's conversion windows article, GA4's attribution settings, Meta's Marketing API reference and its October 2025 developer notice for the January 12, 2026 change. In March 2026 Meta also limited click-through attribution to link clicks for website and in-store conversions, moving likes, shares and saves into "engage-through" attribution.
Attribution window example
An illustrative Dubai shopper clicks an Instagram ad on 1 March, clicks a Google search ad on 5 March and buys an AED 450 item on 10 March. Meta does not count the sale: nine days is outside its 7-day click window. Google Ads does, because five days is inside 30. GA4 sees both clicks within its 90-day lookback.
Pitfalls
- Compare windows before comparing platforms, or you compare different rules.
- Shortening a window lowers reported results without changing what happened.
- B2B deals can take longer than GA4's 90-day maximum, so early touches drop out.
Related terms
See view-through conversions, attribution models and de-duplicated conversions.
How Grower helps
Grower's attribution engine de-duplicates conversions from every connected channel and app into one count, so a sale two platforms claim under different windows is counted once.
Frequently asked questions
What is Meta's default attribution window?
Meta's Marketing API reference says the default setting means 7-day click plus 1-day view. Since January 12, 2026, Meta's Ads Insights API no longer returns 7-day view or 28-day view data. In March 2026 Meta also began counting only link clicks as click-through for website and in-store conversions, with other engagement reported as engage-through.
What is the default conversion window in Google Ads?
Google Ads uses a 30-day click-through conversion window by default, which you can change per conversion action, up to 90 days depending on the conversion source. The default view-through window is 1 day. Conversions outside the window are not counted for that ad, even if the customer clicked it earlier.
How long should my attribution window be?
Match it to your buying cycle. Check the typical time between first visit and purchase in your own data, then pick windows that cover most journeys. Fast ecommerce sales may fit 7 days. Considered purchases and B2B deals need longer windows, or CRM data, so early touches are not lost.
See every channel on one de-duplicated count, whatever each platform's window: book a Grower demo, or read why GA4, Meta and Google Ads disagree.