ROI, ROAS, and ROMI: What is the difference, and which one should you use?

When allocating budgets across OOH, DOOH, search, social, TV, and retail, three acronyms quickly become central: ROI, ROAS, and ROMI. They may sound similar, but they measure different things, and your choice of metric can determine whether out-of-home advertising is viewed as a cost or as one of the most powerful engines in your media mix.

Below, we break down the differences, how to calculate them, and when each metric is most useful in an OOH/DOOH-driven media strategy.

1. ROI: The big picture of the business

What is it?

Return on Investment (ROI) measures the total return on an investment: how much profit you get back in relation to what you have invested. It is used widely in general business and finance, not just in marketing.

• Formula: (Profit – Cost) / Cost

How does it relate to OOH/DOOH?

When looking at ROI, you want to see how the entire marketing budget contributes to results, not just the “last click” from a digital ad. OOH often plays a larger role than “last-click” models reveal:

• OOH builds mental availability and demand, which is subsequently captured via search, programmatic, social, and in-store.

• Studies from the OAAA show that reallocating even a small portion of an existing budget to OOH can result in clear gains in both sales ROI and brand metrics without increasing total spend.

When to use it:

• To evaluate the entire marketing effort from a business perspective.

• When communicating with a CFO or management to show how marketing budgets impact results and profitability.

• When optimizing the media mix at the portfolio level (e.g., how much to spend on OOH/DOOH compared to other channels).

2. ROAS: Sharpness at the channel level

What is it?

Return on Ad Spend (ROAS) focuses on revenue per ad dollar, usually within a specific channel or campaign. It is the most common metric in digital marketing.

• Formula: Revenue from campaign / Ad spend

• Note: ROAS does not account for costs outside of the media buy (e.g., staff, tech, agency fees).

How does it relate to OOH/DOOH?

OOH and DOOH often influence the ROAS of other channels more than their own “on-paper” channel ROAS:

• OAAA analysis shows that when a portion of TV and digital budgets is shifted to OOH, both ROAS and brand metrics rise, as campaigns reach an optimal efficiency level rather than over-investing in the same saturated digital surfaces.

• Analysts often find that OOH-exposed areas show higher search and social ROAS, simply because more people are already aware of the brand when they encounter a digital ad later.

When to use it:

• To compare how different channels perform in pure revenue per media dollar.

• When optimizing tactical investments within DOOH networks, paid search, or social.

• To prove the “priming effect”: compare ROAS in areas where an OOH campaign is active versus control areas without OOH support.

3. ROMI: The Marketing Manager’s favorite metric

What is it?

Return on Marketing Investment (ROMI) is essentially the ROI of marketing. The focus is on the profit or contribution generated by marketing initiatives after deducting marketing costs.

• Formula: (Profit from marketing – Marketing cost) / Marketing cost

• ROMI is often used alongside Marketing Mix Models (MMM) and incremental testing to compare everything from brand campaigns in OOH to “always-on” search.

How does it relate to OOH/DOOH?

OOH/DOOH provides both short-term and long-term contributions:

• Short-term: Campaign-driven sales lifts in exposed areas.

• Long-term: Stronger brand equity, higher preference, and higher conversion rates across all channels.

• To capture the true contribution of OOH, you need the ROMI perspective, where both brand impact and sales are accounted for. International studies (e.g., Omnicom/Benchmarketing) suggest that an optimized OOH share in the media mix provides superior ROMI precisely because the effect spills over into other channels.

When to use it:

• To prioritize major strategic initiatives: e.g., “national OOH launch” vs. “increased always-on budget in social.”

• When building business cases to increase the OOH/DOOH share in the mix.

• To balance short-term performance with long-term brand building.

Comparison Table: Which one should you choose?

Conclusion: Choose the metric based on the decision

• Use ROAS when optimizing tactical buys and demonstrating how OOH/DOOH improves performance in other channels.

• Use ROMI when allocating the marketing budget and proving the value of OOH/DOOH in the media mix.

• Use ROI when connecting marketing to the company’s overall profitability.

By combining these three perspectives, you gain a fairer picture of out-of-home advertising—not as an isolated line item in a report, but as a key component that elevates the effectiveness of the entire media ecosystem.