iROAS calculator

iROAS is incremental revenue divided by spend: what your advertising actually added, not what it claimed. Enter the spend for the period, the incremental revenue your test measured, and what the platform attributed to itself over the same period.

Ad spend in the period ($)

Incremental revenue from your test ($)

Platform-attributed revenue ($)

iROAS (the real number)

1.50

Platform ROAS (the claimed number)

4.20

Incrementality factor

36%

The platform over-reports this channel by 2.8x. Going forward, multiply its reported revenue by 36% to estimate real contribution.

What the incrementality factor is for

You cannot run a test every week, but you look at platform dashboards every day. The factor bridges the two: multiply platform-reported revenue by the factor to get a defensible estimate of real contribution between tests. Background: what is iROAS and the incrementality testing guide.