Conversion window

What it is

A conversion window, also called an attribution or lookback window, is the rule that decides how long an ad interaction stays eligible to take credit for a conversion. Most platforms define separate windows for clicks and for views, with view windows usually much shorter than click windows. The setting sits inside the ad platform's conversion tracking configuration rather than in your analytics tool.

Why it matters

The window length directly changes how many conversions a channel appears to produce, which in turn changes reported cost per acquisition, return on ad spend and any automated bidding that learns from those numbers. Long consideration journeys, common in B2B, high value retail and services, will look unprofitable if the window is shorter than the real decision cycle. Because platforms differ, mismatched windows are a frequent cause of arguments between channel reports and the finance view of revenue.

How it works

Practitioners start by measuring the real time from first click to purchase, then set the window to cover the bulk of that distribution rather than defaulting to whatever the platform suggests. They keep windows consistent across campaigns within a channel so that comparisons hold, document any change with a date so before and after reporting is not read as performance movement, and allow for a reporting lag before judging recent periods. Some teams run a shorter window for fast moving promotions and a longer one for considered purchases, tracked as separate conversion actions.

When it applies

It applies whenever you run paid media with platform side conversion tracking, and matters most where the buying cycle is long or where several channels claim the same sale.

Examples

• A B2B software advertiser finds most demo requests come 20 to 40 days after the first click, so extends the click window beyond the platform default and sees reported cost per lead fall.
• A retailer compares a 7 day and a 1 day click window during a sale period and uses the gap to estimate how much credit comes from delayed purchases.
• An agency shortens the view-through window on a display campaign because reported conversions far exceed the orders recorded in the ecommerce back office.

How it is measured

• Time lag from click to conversion, shown as a distribution rather than an average
• Conversions and cost per acquisition reported under different window settings for the same period
• Share of conversions occurring after day one, day seven and day 30
• Platform reported conversions compared with orders confirmed in the CRM or order system