ROAS or MER - Which DTC Metric Matters More in 2026?

Marketing, when done well, is a very data-driven process. You aren't making choices arbitrarily, you aren't just mindlessly following the whims of the market, you're building experiments and testing strategies. Build, execute, analyze, iterate, repeat.

That's great to know in concept, but what metrics, specifically, should you be focusing on? Two that come up a lot in marketing are ROAS and MER. Which one should be your guiding light? Well, it helps to know what they are, how they work, and why they're useful. So, let's talk about it.

Exploring ROAS

ROAS stands for Return On Ad Spend.

ROAS is a very simple metric, and it's a very easy metric to calculate. Many ad platforms even just give you the number. On paper, it sounds perfect.

To calculate ROAS, all you need is the amount of money you spent on your advertising and the amount of money you've earned attributable to that advertising.

If you spent $5,000 on ads for the month of December, and the people who clicked those ads went on and purchased $25,000 worth of products, you have those numbers. Revenue divided by spend = $25,000 / $5,000 = 5, for a return on ad spend of 5x. 

You've very likely encountered ROAS a lot. It's in the forefront of every ad dashboard, it's at the top of a lot of business reporting, and it's the subject of a million marketing and optimization guides. Unfortunately, it's not as good a metric as it seems.

The Problems with ROAS

There's a lot wrong with ROAS that you wouldn't know just looking at the definition.

The biggest issue is that it's heavily dependent on the specific platform you're using. The actual definition and calculation of ROAS is the same, but the tracking of what sales can be attributed to what channels is much, much harder to validate. Consider some of the questions you might want to answer:

• Was a given sale a first-time sale or a repeat customer? Remarketing ads often have a significantly higher return and can inflate ROAS metrics, since a lot of the marketing work was done before the ad exists.
• Was the ad a deciding factor? Much of marketing centers around building a brand and reputation. Customers who are ready to buy but haven't had the chance can click an ad and take that opportunity, but it wasn't the ad itself that did the work.
• Are you making a profit from your transactions? Even with a high ROAS, your other costs can be high enough that you aren't actually profiting from those sales, even if the ROAS is positive. ROAS only accounts for ad spend, not other costs in doing business.

There's also the issue of overlap.

Modern customer journeys typically involve many different points of contact between your brand and the customer. In fact, a big selling point of a lot of modern ad platforms is the ability to view a "complete" customer journey, and track a dozen or more of those touchpoints along the way.

What happens if several of those touchpoints are ads, either different ads in the same platform or ads across different platforms? It's very common for touchpoints to be double-counted, especially across platforms, making your ROAS look better than it actually is.

In fact, one thing I've seen a lot before is a green-covered dashboard with all kinds of great-looking ROAS metrics, and a business bleeding cash and coming nowhere close to breaking even, let alone profiting. If you've ever experienced a situation like this, it may be worth reviewing why your Facebook ROAS dropped suddenly to understand how volatile these numbers can be.

Clearly, ROAS has problems. So what is MER, and does it solve those problems?

Exploring MER

MER stands for Marketing Efficiency Ratio.

It's very similar to ROAS, but broader and, surprisingly, more accurate and useful.

Marketing Efficiency Ratio is calculated in the same way as ROAS: your revenue divided by your expenses. But it's broader, and it's not limited to just one platform, channel, or campaign.

Total revenue is an easy number to get. Total spend can be a little harder. You have to think of all of the things that go into your marketing spending. The cost of running a blog, the cost of ads, the cost of other paid media, the cost of agency marketing, the cost of influencer payments, and on and on.

Technically, there are two kinds of MER, as well.

First, you have NMER, which is New Customer MER. This is a subset of MER focusing solely on the revenue that comes from newly gained customers. Then you have BMER (also sometimes called AMER), which is Blended or All MER. This is your total MER

The better your MER, the more effective your marketing as a whole is at converting money into revenue. 

The Problems with MER

There are a few issues with MER, even if it sounds like just a better metric.

One of the biggest issues with MER is that it's too broad and unfocused for very granular decision-making. It covers your marketing as a whole, but it doesn't tell you which parts of your marketing are doing well and which aren't. Maybe your blog is pulling a lot of weight, while your Facebook ads are barely breaking even. Maybe your Instagram ads are doing great, but your Google ads are a money pit. 

When you're only looking at MER, you're losing that comparative perspective. You can end up using one good channel to subsidize another bad channel, without realizing that's what's happening.

MER is also not quite aligned with your overall profit and loss calculations. MER accounts for all of your marketing spend, but it doesn't account for non-marketing expenses. COGS, fulfillment costs, operational costs, and other expenses add up outside of marketing, so MER is only one part of the overall financial picture.

Another gap is that MER doesn't account for sales that come from outside of your marketing channels. Organic purchases, word of mouth purchases, and other sources are counted in MER because of the revenue they generate, but since they weren't actually bought by your marketing, the attribution is false.

I've seen this happen with word-of-mouth recommendations. A post going viral and getting people talking about a business can convert into a lot of unexpected sales with, realistically, $0 in attributable marketing to it. But it still counts for MER.

How Do ROAS and MER Compare?

I've already mentioned that ROAS has a lot of problems, but that doesn't make it useless. The two metrics are useful in different ways and for different purposes.

The biggest problem I run into is simply that many people treat ROAS as if it were MER, when it's distinctly not.

ROAS measures your conversion efficiency within a narrow frame. It's just one platform, one window into one string of commercial touchpoints. Usually, it's limited to just seven days since a click, and one day since a view. This is a surprisingly narrow view, and gives you only a partial glimpse on your marketing performance.

By contrast, MER is a broad scope. It shows the full, overall efficiency of your marketing. The downside is that you lose some of that granularity. You can't really drill down into your MER and find information about different ad platforms or different campaigns. That's where ROAS shines; as a metric for a narrow, specific part of your marketing.

Another critical difference centers around how the data is harvested and reported.

With MER, it's all absolute data. You can calculate MER out of your bank statements. Money in, money out, end of story.

With ROAS, it's all about attribution tracking within the field of view of the platform. DTC attribution tools can help here, but there are still fundamental limitations.

• What happens if the tracking code breaks or is blocked by a user?
• What happens if the ad platform changes their attribution tracking model?
• What happens if a third party, like a web browser, changes their tracking?

It's very easy for the underlying data to shift, often in ways you have no way of even knowing happened, let alone how it affects your metrics. 

On that front, MER wins hands down. It's not subject to noise, variability, code issues, or algorithmic change. The numbers can't lie to you.

Why ROAS is Still Popular

MER is more or less a clear winner for many use cases, including the uses many businesses are using ROAS for, so why isn't MER more common?

The biggest reason is that ROAS is easy. It's right there. Every ad platform is going to show you ROAS front and center. They'll even give you tips to improve your ROAS right there on their platform.

And of course they do; why not? Many decisions that improve ROAS are great… for short-term profits, but not for long-term success. In fact, ROAS is almost more beneficial to the ad platform than it is to your business. That's why it's so common to see businesses with a positive ROAS but a neutral or negative cash flow.

ROAS is a big, bright metric front and center on every dashboard, and that makes it easy to report on.

It's also easy to make look good. ROAS is, relatively speaking, easy to improve. It's easy to optimize ad campaigns for attributable sales, especially if you're just pushing for short-term, high-value sales. Pumping those numbers up is both low effort and looks great on reports to shareholders.

MER is, while more realistic, usually less flattering. After all, there's a lot of marketing money that goes to places that don't have obvious returns. All the reputation building, all the content marketing, and the AI citation building, none of it is an easy touchpoint to attribute a sale to. 

If you're responsible for showcasing company performance to stakeholders, which would you rather have on the top of your slide deck: a 5.0 ROAS or a 2.4 MER? The bigger numbers look better.

There's also a little bit of defensiveness in some situations.

What do I mean by that? Specifically, with agencies. When an agency is running ads for a company, they report their performance to their client. Using ROAS is simple, easy, and obvious. And, it's more realistic for the performance of the agency.

If an agency uses MER, not only is it a less flattering number, but it's also calculated using expenses the agency likely can't control. It's fairly rare for a business to hand over 100% of its marketing to an agency, right? There are always costs and expenses not handled by the agency. This means at least part of the reporting metric, the one the company is using to judge the agency's performance, is out of the agency's hands.

If you're paying an ad agency and they're reporting using MER, and you crank up investment in content marketing on the side, MER drops, which makes the agency look worse, through no fault of their own. Feels bad, man.

Which Metric is Better for 2026?

We're now 1,500 words deep in a post that, so far, seems like I'm going all-in on MER. But that's not quite the case.

In fact, both metrics have their uses.

MER is better across the board for broad-spectrum reporting and for a more realistic take on the success of a business's marketing budget.

Use MER when you want to have a bird's eye view of your performance, when you're checking your overall efficiency and whether or not scaling your budget makes sense, and when you need to figure out how to align your marketing with other performance goals.

ROAS is better for narrower, more comparative evaluations.

Specifically, ROAS needs to be used in an apples-to-apples comparison. Compare one Google Ads campaign to another. Compare a Meta or Instagram campaign to another. Compare like to like.

When you start comparing across platforms, that's when you start running into problems. Cross-platform attribution, different models, different data sources, they all mean you aren't comparing accurate, similar data points. Moreover, it fails to capture the whole of your marketing.

The correct answer is to use both metrics for their purposes. 

Personally, I'm a data-head. I'd rather have a dashboard with twelve different metrics showing me different viewpoints than have one big metric to show to a client. I want a full picture, not a flattering picture. I find it works best to make data-driven decisions, and I think that's what my clients deserve.