Attribution window

What is Meta's default attribution window?

Seven days from a click, and one day from a view without a click. For ad sets optimising for website conversions, Meta also credits a one-day engage-through, which counts a shopper who watched enough of a video before converting. Both defaults apply unless the ad set says otherwise.

What changed in January 2026?

Meta removed the seven-day view and twenty-eight-day view windows on 12 January 2026. Sales that a shopper made days after seeing an ad without clicking it stopped being attributed at all, which cut reported conversions on awareness and video campaigns without anything changing in the campaigns themselves.

This is the likeliest explanation for a drop in reported conversions dated around mid-January 2026, and it is a reporting change rather than a performance one.

Does a longer attribution window mean better performance?

No. A longer window credits more sales to the same spend, so the reported return rises without a single extra order being placed. Comparing two periods, or two campaigns, is only meaningful when both are measured on the same window.