Attribution window (lookback window)

Updated 2026-11-02

Definition

An attribution window, also called a lookback window, is the period before a sale in which a visit can earn credit. A 90-day window means only visits in the 90 days before the payment count. Older visits are ignored.

The window limits how far back the attribution model looks. It doesn't change what you tracked. It only changes which of those visits are eligible for credit.

Example

This example uses made-up numbers. Priya pays $600 on September 30. The visits were:

• January 15: a blog post from organic search
• August 20: a newsletter click
• September 28: a Google Ads click

With a 90-day window, the January visit falls outside the window. Linear attribution splits $600 across two visits, giving $300 to email and $300 to paid search.

With a 365-day window, all three visits count. Each gets $200, and organic search now shows up.

Choosing a window

Match the window to how long people take to buy. A low-cost tool bought in a week can use a short window. A product that needs a team's sign-off may need a longer one. Look at the time between first visit and first payment for your own buyers, then set the window so most of them fit.

A very short window favors late channels such as branded search. A very long window can credit visits that had little to do with the sale. If no visit falls in the window, the payment becomes unattributed revenue.

How Headstream measures it

Headstream defaults to a 90-day lookback window. You can change it in your project settings, under Project details. The window is set per project in days, and each attribution run records the window it used. Changes are listed in the project change log, so you can see why a number moved after an edit.