Attribution Window Overkill
A purchase-category conversion action on your account uses a click-through attribution window longer than 30 days. For most direct-response purchase flows, that window is wider than the actual buying behavior. The action will end up crediting clicks that occurred weeks before the purchase, even when those clicks had no causal role.
Why It Matters
Google Ads lets you set the click-through window per conversion action, with options up to 90 days. For B2B and considered-purchase categories, long windows often match the real sales cycle. For ecommerce purchase flows where the median click-to-purchase delay is hours or a few days, a 60- or 90-day window introduces noise rather than accuracy. The practical effect: a user clicks a brand search ad in week one, never returns through paid, and buys organically in week eight. With a 90-day window, that purchase still gets credited to the week-one click and shows up in the campaign's conversion column. The campaign looks more efficient than it is. Smart Bidding scales spend on it. Newer, harder-to-attribute campaigns lose budget by comparison. The right window is the one that captures roughly the 90th percentile of real click-to-purchase delay. Pull the Time Lag report under Reports, Predefined, Time, and read the actual distribution before setting the window.
How To Fix It
- In Google Ads, open Reports, Predefined, Time, Time lag. Filter to the flagged purchase action.
- Identify the time bucket containing the 90th percentile of conversions. For typical ecommerce, that lands at 7 to 14 days.
- Open Tools and Settings, Conversions, the affected action, and update Click-through conversion window to the smallest window that captures that 90th percentile.
- Annotate the change date in the account history so reported conversion counts that drop after the change are not misread as a campaign issue.
- Allow 4 to 8 weeks of stabilization before judging campaign performance against the new window.
Example
Action: Purchase. Click window: 90 days. Real 90th percentile click-to-purchase delay: 6 days. Window is 15x too wide.A purchase-category conversion action on this Google Ads account uses a click-through attribution window longer than 30 days. Per Google Ads conversion window documentation, the click-through window controls how long after an ad interaction a conversion can be credited to that click. For direct-response purchase flows where the actual click-to-purchase delay is hours or a few days, a 60- or 90-day window credits clicks that had no causal role in the purchase, inflates campaign-reported efficiency, and biases Smart Bidding toward older campaigns at the expense of newer ones. The right window is the smallest one that captures roughly the 90th percentile of real click-to-conversion delay, which can be read directly from the Time Lag report under Reports, Predefined, Time. Fix: review Time Lag for the affected action, shorten the click-through window to match the 90th percentile, annotate the change date, and allow 4 to 8 weeks of stabilization before judging campaign performance against the new baseline. Source: support.google.com/google-ads/answer/3123169.
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References
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