MER is the easiest marketing metric to calculate and one of the hardest to track consistently. Total revenue divided by total marketing spend. No attribution model, no platform self-grading, no argument about which channel touched the buyer last. I explained the basics in what is MER, and how do you calculate it?.
The difficulty is that the inputs live in different places. Revenue is in Shopify. Spend is spread across Meta, Google, TikTok, and whatever else you run, plus costs that never appear in an ad account, like influencer fees and agency retainers. Doing it by hand once a month is easy. Doing it daily, the same way every time, is where a tool earns its place.
Settle the definition first
Before picking a tool, decide three things, because every tool lets you define them differently. Gross or net revenue, meaning before or after refunds and discounts. My preference is net, because refunds are real money and BFCM discounts distort gross. Which spend counts, meaning ad spend only or all paid marketing. Ad spend only is easier to automate, but leaving out influencers and affiliates flatters the number. And whether you also track MER on new-customer revenue only, sometimes called aMER, which strips out the repeat buyers who would have bought anyway. Write the definitions down and keep them fixed.
ThoughtMetric
ThoughtMetric has MER as a standard metric, calculated from your store’s sales and the spend it pulls from connected ad accounts, and shows it over time next to new-customer ROAS and cost per new-customer order. (Disclosure: ThoughtMetric sponsors this site.) Having MER beside channel-level attribution is the useful part, because when MER drops you can go straight to which channel caused it. Pricing starts at $99 a month for 50,000 pageviews with every feature included and a 14-day trial. Spend that does not come through an ad integration, like an influencer invoice, still needs handling outside it, which is true of every tool here.
Triple Whale
Triple Whale puts blended efficiency metrics on its summary view, and many Shopify brands first see MER there. The free plan covers the pixel, first and last click attribution, and ten users. Paid plans start at $219 a month for Foundation on its Shopify listing, scale with annual GMV, and are 12-month subscriptions. If you are already on it, check exactly how its blended metric treats refunds, shipping, and tax before you report it to leadership, since that choice can move the number by several points.
Lebesgue
Lebesgue is the low-cost analytics option with a free tier, an Ultimate plan at $79 a month, and Ultimate AI at $149 a month. Its analytics bring store and ad data together for blended performance reporting, and it adds competitor tracking and benchmarks that are useful for judging whether a falling MER is your problem or the market’s. Its attribution pixel is a separate add-on, which you do not need if MER is the main goal.
Polar Analytics
Polar Analytics suits teams that want MER defined once and used the same way by everyone. Its semantic layer sets metric definitions centrally, which solves the common problem of finance and marketing reporting different MER figures in the same meeting. It also pulls in more spend sources than most tools. Pricing is not listed on the website, so you will need a demo to get a number.
A spreadsheet
Do not underrate it. A Google Sheet with daily Shopify revenue and daily spend pasted from each platform, or pulled in with a connector, gives you an MER you fully control, including the spend no ad integration sees. The downside is labor and the habit of skipping it when busy. For a brand under $2M with two channels, it may be all you need. Past that, the time cost usually exceeds a tool’s subscription.
Reading MER properly
MER is a business-level metric, not a channel metric. It tells you whether marketing overall is getting more or less efficient, and it reacts to things that have nothing to do with ads, like a price change, a viral moment, or a strong email week. Watch it as a seven-day rolling figure rather than daily, set a floor based on your margins, and use attribution to find out why it moved. The relationship between MER and the other efficiency numbers is in MER, blended ROAS, and platform ROAS.
Picking one
- Want MER next to channel attribution so you can see why it moved? ThoughtMetric (our sponsor).
- Already on Triple Whale? Use its blended view, after checking the revenue definition.
- Want low-cost blended reporting plus market benchmarks? Lebesgue.
- Need one governed MER definition across finance and marketing? Polar Analytics.
- Small brand, two channels, and disciplined? A spreadsheet.
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