TLDR: ROI and ROAS are both essential performance metrics, but they tell you very different things. ROAS measures how much revenue your campaigns are generating relative to ad spend, it’s your go-to for day-to-day optimisations. ROI goes deeper, factoring in all business costs to show you whether your marketing activity is actually profitable. The smartest marketers don’t choose one over the other, they use both together to make smarter, more scalable decisions.
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What is ROI? A quick refresher
ROI, or Return on Investment, is a percentage-based metric used across both performance marketing and broader business analytics to measure the profitability of an investment. Unlike simpler revenue metrics, ROI accounts for all associated costs, not just ad spend, but margins, overheads, and any other expenses the business needs to consider.
The calculation looks at net revenue (revenue minus all costs) divided by the total investment. This means ROI can be applied at a channel level, a campaign level, or right across an entire business project.
When ROI is positive or high, it indicates that a campaign or project is genuinely driving profitability, not just generating revenue, but doing so in a way that makes financial sense for the business. When ROI is negative or close to zero, it can be a sign that whilst revenue is being generated, the activity isn’t actually profitable once all costs are factored in. In short, ROI answers the big question: is my business making money?
What is ROAS? And why do marketers love it?
ROAS stands for Return on Ad Spend, and unlike ROI, it’s a channel or campaign-level metric. Rather than looking at profit, ROAS focuses purely on revenue, specifically, how much revenue is being generated for every pound (or dollar) spent on advertising.
The formula is straightforward: revenue divided by ad costs. The simplicity is a big part of why marketers gravitate towards it. The data is readily accessible, you can pull it directly from your ad platforms or from GA4, and it updates constantly, meaning you can track day-to-day and week-to-week changes with ease.
ROAS is particularly useful for making quick, informed decisions around budget allocation and campaign performance. If one campaign is significantly outperforming another on ROAS, that insight can directly inform where you shift budget. It’s agile, practical, and easy to act on.
ROAS vs ROI, what’s the actual difference?
The clearest way to think about the difference is this: ROAS tells you how well your ads are working, while ROI tells you how well your business is working.
Consider a scenario where you’re running campaigns across a broad product inventory with varying margins. On the surface, a campaign might be generating impressive revenue and a healthy ROAS. But once you factor in the margins on the products being sold, the overheads, and other business costs, the actual profitability could look very different. That’s where ROI becomes essential, it gives you the full picture.
ROAS is a faster, more accessible metric suited to campaign-level decision-making. ROI is a broader business metric that requires more data but rewards you with a much more accurate view of whether your marketing is genuinely contributing to business growth. Both are valuable, they just operate at different levels of the business.
When is ROAS the right metric to use?
For day-to-day and weekly campaign optimisations, ROAS is typically the metric of choice. The reason is practical: business costs such as margins and overheads don’t tend to fluctuate dramatically on a daily basis, which means ROAS is a reliable enough proxy for performance at a granular level.
If you’re making decisions about where to shift budget, which campaigns to scale, or how individual channels are performing week on week, ROAS gives you the fast, actionable insight you need. It’s the metric that keeps campaigns moving in the right direction in real time.
When should ROI take priority?
ROI becomes the more important metric when you’re stepping back to review performance at a larger scale or over a longer time frame, think monthly or quarterly business reviews, rather than weekly check-ins.
It’s also the right metric when you need to understand the true efficiency of your marketing investment. At Modo25, we’ve worked with clients where ROI was used as the primary source of truth to review campaign investments and restructure how campaigns were set up across multiple channels, including paid search, paid social, and affiliates. By assigning different margin groups to different campaigns and setting ROAS targets that reflected actual profitability rather than just revenue, we were able to scale efficiency significantly. That freed up budget to reinvest into other growth activities, something that simply wouldn’t have been possible by looking at ROAS alone.
Which is better ROI or ROAS?
Neither metric is objectively better, they serve different purposes and work best when used together. Relying solely on ROAS can give you a misleadingly positive view of performance if your margins are low or your costs are rising. Relying solely on ROI, on the other hand, can make it harder to make quick, practical decisions at a campaign level.
The real answer is that the most effective marketing teams use ROAS to manage campaigns day to day, and ROI to evaluate whether those campaigns are contributing to business growth over time. One without the other gives you an incomplete picture.
How to build a reporting framework that uses both
Building a reporting framework that incorporates both ROAS and ROI doesn’t need to be complicated, but it does require access to the right data.
ROAS is relatively straightforward to calculate, you can use GA4 alongside your platform cost data to generate this on an ongoing basis. ROI requires a little more: you’ll need access to business-level data such as margin information, which might come from Shopify or whatever commerce or finance platform your client or business is using.
Once you have both data points, the most effective approach is to track them side by side on a weekly basis. Comparing your GA4 ROAS to your ROI week on week allows you to see how the gap between the two fluctuates over time. In an ideal scenario, the difference between the two metrics should remain relatively consistent. If it starts to diverge, for example, if ROI is declining while ROAS remains stable, that’s an early indicator that something has changed on the cost side of the business. Shipping costs may have increased, margins may have shifted, or overheads may have grown. Identifying that quickly means you can have an informed conversation about how to adjust budgets or strategy before it becomes a bigger problem.
It’s also worth building in longer-term averages alongside the weekly view, looking at three, six, and twelve month windows helps surface trends and anomalies that week-on-week data might mask. That broader perspective is what turns a reporting dashboard into a genuine strategic tool. If you would like to learn more about ROAS or ROI or to discuss how we can help with your campaign, feel free to send us an email to team@modo25.com
