What is Cohort vs Calendar ROAS? Complete Guide for 2026

What Cohort and Calendar ROAS Mean

Return on ad spend can be measured two ways, and they answer different questions.

Calendar ROAS takes the revenue earned during a period, from any user, and divides it by the ad spend in that same period. It is simple, and it is how most finance reports are structured.

Cohort ROAS groups users by the day (or campaign) that acquired them and follows that group's revenue over time. Each cohort's revenue is divided by the spend that acquired it. This is cohort analysis applied to return on spend.

Why the Two Disagree

Calendar ROAS mixes users of different ages. Revenue earned today includes purchases from users who installed last week or last month, but the spend in the denominator is only today's.

• When you cut spend, calendar ROAS rises, because older cohorts keep paying while new spend shrinks.
• When you scale spend, calendar ROAS falls, because the new users have not yet produced their revenue.
• When a campaign has a long purchase delay, calendar ROAS credits the revenue to the wrong day.

Cohort ROAS avoids this by tying revenue back to the spend that acquired the user, so a campaign is judged on what it actually produced.

How to Read Cohort ROAS

1. Pick the ages you care about, for example day 0, day 7 and day 30.
2. Read every campaign at the same age before comparing.
3. Wait for the age to complete before judging a cohort; a three-day-old cohort will always look weaker than a month-old one.
4. Use the early ages to steer budget and the later ages to confirm payback.

Cohort ROAS in Linkrunner

Linkrunner reports ROAS by campaign on a cohort basis, with each install credited to one source, so campaigns are compared on the revenue their own users generated. The Reporting API returns day-wise revenue for day 0, day 3, day 7 and day 30, which supports reading each cohort at a fixed age.