Attribution window

An attribution window, also called a lookback or conversion window, is the time limit on credit. A purchase eight days after a click does not count for that click if the window is seven days.

Defaults differ by tool, which is one reason their numbers differ:

• Meta: 7-day click and 1-day view for most website conversion campaigns, plus a 1-day engage-through window since 2026.
• Google Ads: 30 days for Search and Display unless you change it, with 1 to 90 days allowed (Google).
• GA4: 90 days for most key events and 30 days for first visits by default (Google).

A longer window credits more sales to the channel, and some of those sales would have happened anyway. A shorter one undercounts channels with long buying cycles. Compare tools only after setting their windows to match, as far as each allows. See why analytics numbers never match.