Ad platforms love to tell you your ROAS is great. Your bank account sometimes disagrees. That gap usually comes down to one thing: people misuse or misread the ROAS formula, then make budget decisions based on a number that doesn't mean what they think it means.

This post walks through the actual formula, where the math goes wrong, and what a "good" ROAS really looks like once margin enters the picture.

What ROAS Actually Measures