Key takeaways
- ROAS is revenue divided by ad spend. ROI is profit divided by total cost. They answer different questions.
- A ROAS that looks healthy can hide a loss once product cost, fees, returns and labour are counted.
- Use ROAS for day-to-day channel optimisation, ROI for investment decisions, and break-even ROAS to connect the two.
- Define revenue, cost and attribution window before comparing numbers.
01
What is the difference between ROAS and ROI?
Return on ad spend, ROAS, is revenue attributed to ads divided by ad spend. If 1,000 of spend produces 4,000 of revenue, ROAS is 4. Return on investment, ROI, is profit divided by cost: net profit after all costs compared with what you invested.
ROAS ignores everything except the ad cost. ROI includes cost of goods, delivery, agency fees, tools and staff time. That is why the two can point in opposite directions.
02
How does a worked example differ?
Illustrative figures: ad spend 1,000, revenue 4,000, so ROAS is 4. If costs of goods and delivery are 70 percent of revenue and fees are 500, profit is 4,000 − 2,800 − 1,000 − 500 = −300. ROI is negative even though ROAS looks strong.
Break-even ROAS is 1 divided by gross margin after other variable costs. In the example, margin before fees is 30 percent, so break-even ROAS is above 3.3 before any fixed costs.
| Metric | Formula | Question it answers |
|---|---|---|
| ROAS | Revenue ÷ ad spend | Is this channel efficient at generating sales? |
| ROI | (Revenue − total cost) ÷ total cost | Was the investment worth it overall? |
| Break-even ROAS | 1 ÷ margin | What ROAS do we need not to lose money? |
| CAC payback | CAC ÷ monthly gross profit | How long until the customer repays acquisition? |
03
When should you use each?
Use ROAS inside a channel to compare campaigns and set bidding targets, with break-even ROAS as the floor. Use ROI for budget decisions across channels and for reporting to finance. For subscriptions or repeat business, use lifetime value and payback period rather than first-order ROAS.
Be consistent about attribution. Platform-reported revenue can overlap across channels; reconcile it with CRM or finance data before treating the totals as truth.
- Set targets from margin, not from habit
- Compare ROAS to break-even, not to averages
- Reconcile platform and CRM revenue
- Use payback for recurring revenue
- State the attribution window
04
What goes wrong in reporting?
Typical mistakes include counting revenue that was refunded, mixing gross and net revenue, ignoring assisted conversions and comparing channels with different attribution rules. Another is optimising the ROAS number by only bidding on brand terms, which captures demand rather than creating it.
Report both numbers with definitions, and show how they were calculated. A smaller, honest figure is more useful than a larger one nobody trusts.
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Primary sources and further reading
Use the source material to validate details against your own context and current platform configuration.
- Google Ads Help: About conversion tracking
- Google Ads Help: About Smart Bidding
- HubSpot: Use lifecycle stages
This field note follows the XenGrowth editorial policy: primary sources where available, visible limitations, material review dates, and no invented first-hand experience.
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