ROAS Measurement: How to Calculate It Without Fooling Yourself
Return on ad spend compares attributed revenue with advertising cost. The arithmetic is simple; the measurement choices behind both numbers are not.
The formula
ROAS = attributed revenue รท ad spend. A result of 3 means three units of attributed revenue for each unit of ad spend.
Revenue definition matters
Gross revenue, net revenue, collected cash, subscription value, and lifetime value can produce very different ROAS figures.
Attribution changes the numerator
If a platform credits itself for a conversion another system assigns elsewhere, reported ROAS changes even when spend and actual business revenue do not.
Profitability is broader than ROAS
COGS, refunds, payment fees, shipping, sales costs, and overhead are outside basic ROAS. A high ROAS is not automatically high profit.
Use a consistent decision view
Choose a revenue and attribution definition appropriate to the decision, then use it consistently enough to compare campaigns.