Marketing ROI in plain English (and why it is not the same as ROAS)

ROI is a question about profit

Return on investment sounds intimidating, but the idea is simple: after everything this campaign cost, did it make the business more money than it consumed? ROI is a question about profit, not revenue. That single distinction is what separates it from ROAS, and it is why your CFO cares about one number much more than the other.

In plain terms: marketing ROI takes the additional gross profit a campaign genuinely caused, subtracts the full cost of running it, and expresses what is left as a percentage of that cost.

The three questions behind any honest ROI number

You do not need to run the calculation yourself to talk about ROI credibly. You need to know the three questions that sit underneath it, because these are the questions a finance director will ask:

• How much of the revenue was genuinely additional? Some customers would have bought anyway. Honest ROI only counts the sales the campaign actually caused.
• What is that revenue worth in profit? Revenue is converted to gross profit using the margin on what was sold.
• What did the campaign really cost? Media plus production, agencies, tools and any other supporting costs.

A quick example

A campaign is credited with £400,000 of revenue. Testing suggests 70% of it was genuinely additional, and the gross margin is 45% - so the campaign produced £126,000 of additional gross profit. The full campaign cost, including £20,000 of supporting spend on top of the media, was £120,000. The campaign ROI is (£126,000 - £120,000) / £120,000 = 5%.

Notice how different that feels from a platform-reported ROAS of 4x on the same campaign. Both numbers can be true at once - they are just answering different questions.

What to do with this

Before you quote any ROI figure, check you could answer the three questions above. If you can, you will sound more commercially credible than most marketers in the room. If you cannot, say what you know and what you are still measuring - that honesty builds more trust than a polished number.

When you are ready for the full worked calculation, including a complete cost checklist and an incrementality sensitivity table, read our step-by-step guide to calculating marketing ROI.