How To Calculate Marketing Roi

The base formula

Attribution is the question “which campaign caused this purchase?” Most conversions involve 3–8 touchpoints — a Google ad, a retargeting display, an email, an organic search, a podcast mention — and attribution models assign credit differently:

Marketing ROI vs ROAS — don’t confuse them

The honest version of ROI always names the attribution model alongside the number. “Campaign ROI: 240% (last-click)” is truthful. “Campaign ROI: 240%” alone is a number someone will disagree with the second it shows up in the monthly review.

Three common flavors of Marketing ROI

Most teams skip this because it feels like losing conversions on purpose. The ones that run holdouts routinely find that 20–50% of “attributed” conversions are non-incremental. If you haven’t run a holdout test, your reported ROI is optimistic by an unknown amount.

The time-horizon problem

LinkedIn ads for an enterprise SaaS. Spend: $15,000. Attributed revenue (last-click, GA): $180,000 in first-year contract value. Gross margin: 75%. Ad-ops labor (10% of media cost allocated): $1,500.

Attribution — where ROI claims go to die

Now discount for attribution model risk. If an incrementality test would show 60% of those conversions were non-incremental, real-world ROI = ($135,000 × 0.40 − $16,500) / $16,500 = 227%. Still profitable, but dramatically different, and only one is going to be defensible six months later.

Incrementality — the harder question

For campaigns under $10k in spend and under 100 conversions, skip the attribution modeling. Just look at spend and revenue from matching time periods, accept last-click attribution as good-enough, and calculate gross-profit ROI. The variance is too high for precision modeling to beat back-of-envelope at that scale.

A campaign-level ROI worked example

The shortcut for small campaigns