Module 02 · Marketing Data Science Made Easy

Break-even from contribution margin

The floor under Total ROAS. Below it, ads are not clearing the stack on average.

Formula. Break-even Total ROAS ≈ 1 ÷ contribution margin. At 35% margin, break-even ≈ 2.86×.

Break-even Total ROAS ≈ 1 ÷ contribution margin

Decision this module trains Is this period’s Total ROAS above or below the floor? One sentence only — no channel causality claim.

What goes in “margin”

Contribution margin after the costs that scale with an order: COGS, variable shipping, payment fees, variable packaging — whatever your finance stack treats as till-level. Be consistent month to month. Perfection is optional; a stable definition is not.

How to read the comparison

Total ROAS ≥ break-even — portfolio clears the floor on average.
Total ROAS < break-even — something must change: spend, mix, offer, or margin.
Not causal — clearing the floor does not prove a channel “worked.”

Lab — break-even slider

Contribution margin: 35% Your Total ROAS (optional, e.g. 3.1)

Move margin; compare to a live Total ROAS you trust for the same period.

Retrieve

Margin 40% → break-even Total ROAS = ? If live Total ROAS is 2.2×, above or below the floor?

Paid pack has the worksheet: break-even-stack.md.

Full break-even calculator

Buy $79 — get course pack Free desk help Custom inquire