Lookback Window

The lookback window is the time horizon a report uses to find qualifying ad interactions for the orders being analysed. A 14-day lookback report for the week of June 10–16 scans clicks as far back as May 27 when assigning credit for orders placed in that week.

It is easy to confuse with attribution window. The shortest way to remember:

• Attribution window = forward-looking eligibility of one click.
• Lookback window = backward-looking scope of one report.

A 7-day attribution window plus a 14-day lookback report will still only credit clicks within 7 days of each order — the lookback simply bounds how old the order itself can be in scan terms.

Where you actually set it

• Sponsored Ads reports: pick a date range and an attribution window; the lookback is implicit (= reporting period length + attribution window).
• Search Query Performance: weekly and monthly aggregations are fixed.
• Brand Analytics: typically 1, 7, 30, or 90 days.
• Amazon Marketing Cloud: lookback is explicit per query, up to 28 months of stored data.

Why this matters operationally

When you re-pull a Sponsored Products report 30 days later, ACOS will be lower than what you saw the first week. Delayed conversions inside the 7-day attribution window keep arriving for days after the click. A campaign that looked like 42% ACOS on Monday often settles at 28% by the following Monday. This is normal — not a reporting error.

Rule-of-thumb maturation:

Common mistakes

• Reading day-of ACOS as final. Optimisation decisions on intra-day or T+1 numbers chase noise.
• Comparing reports pulled at different ages. A 30-day-old report against a 1-day-old report will always show the older one as more efficient.
• Confusing lookback with attribution. The two interact but are not interchangeable.