# What is MER (Marketing Efficiency Ratio) and how to calculate it > The one marketing metric that doesn't depend on pixels, cookies or attribution windows. It comes straight out of your P&L. Source: https://www.nashmarketinglabs.com/en/blog/what-is-mer-marketing-efficiency-ratio Author: Nash Marketing Labs, a paid media agency (Google Ads, Meta Ads, TikTok Ads, LinkedIn Ads). Date: 2026-10-21 --- **MER (Marketing Efficiency Ratio) is your business's total revenue divided by your total advertising spend over the same period.** If you generate €100,000 in revenue in a month and spend €25,000 on ads, your MER is 4. It is expressed as a multiple, not a percentage, and its big advantage is that it doesn't depend on attribution at all: both numbers come from your back office and your invoices. It answers the question leadership asks first: _for every euro we put into advertising, how many euros come into the company?_ You will also see it called blended ROAS or aggregate ROAS. Same formula, different name. ## The formula, with a worked example **MER = total business revenue ÷ total advertising spend** An online store in September: - Total revenue (every channel, including organic and email): **€184,000** - Meta Ads spend: €28,000 - Google Ads spend: €19,000 - TikTok Ads spend: €5,000 - **Total ad spend: €52,000** MER = 184,000 ÷ 52,000 = **3.54** Notice what is _not_ in that calculation: no attributed conversions, no 7-day click window, no pixel events. That is why finance teams trust MER far more than any platform dashboard. The inverse is just as useful: **1 ÷ MER = the share of revenue that goes on advertising**. In the example, 1 ÷ 3.54 = 28.2%. Outside the marketing team, that version is usually easier to read. ## How to set your target MER (from margin, not from ambition) A MER of 3 can be excellent or ruinous depending on your margin. Work out your target like this: - **Calculate your contribution margin** as a percentage: selling price minus cost of goods, shipping, payment fees and returns (gross margin after variable costs). Say 42%. - **Decide how much of that margin you will spend on acquisition.** The rest pays for overheads and profit. If you allocate half, that is 21 of the 42 points. - **Your target MER is 1 ÷ 0.21 = 4.76.** Above it, advertising pays its share; below it, you are buying revenue and paying for the privilege. The same arithmetic, for a few common margins, if you allocate half of the margin to advertising: Contribution marginBreak-even MER (all margin to ads)Target MER (half the margin to ads) 25%4.08.0 40%2.55.0 55%1.83.6 70%1.42.9 Two things change the number and have to go into the calculation: - **Repeat purchases.** If a customer buys 2.3 times a year on average, the first order can run at a much lower MER because the profit arrives later. Look at it next to your [LTV:CAC ratio](https://www.nashmarketinglabs.com/en/blog/ltv-cac-ratio) before you lower the bar. - **Fixed costs.** If your overheads are high you need contribution, not just break-even. The target MER goes up. ## MER, ROAS and acquisition MER: what each one measures MetricFormulaWhat it tells you MERTotal revenue ÷ total ad spendWhether advertising, as a whole, pays off for the business ROASRevenue the platform attributes to itself ÷ spend on that platformWhich campaign, ad set or creative works best inside one platform Acquisition MER (aMER)Revenue from new customers ÷ total ad spendWhether advertising is buying new customers or re-selling to existing ones The rule we use: **MER decides how much you spend, ROAS decides where**. Acquisition MER is the early warning: if total MER holds but acquisition MER falls, the account is living off returning customers and growth will stall a quarter later. The full comparison is in [MER vs ROAS: which metric to use and when](https://www.nashmarketinglabs.com/en/blog/mer-vs-roas). ## The three calculation mistakes that wreck the number - **Using gross revenue in the numerator.** Revenue with VAT, with shipping charged to the customer and before returns inflates MER without the business getting any better. Use net revenue, and use the same definition every month. - **Leaving spend out of the denominator.** MER is _all_ advertising: affiliates, influencers, comparison sites, sponsorships. Count only Meta and Google and your MER comes out artificially high. - **Mismatched periods.** Platform invoices and revenue must cover the same dates. If you ship later than you sell, decide whether revenue counts on order date or ship date. Pick one and never change it. ## What to do when MER moves MER isn't read in absolute terms. You read the trend against your target: - **MER above target and stable.** You have room. Our rule of thumb: raise spend by 15-20% and measure again in two weeks. If MER holds, repeat. - **MER falling with flat spend.** The budget isn't the problem: the account, the creative or the market is. Drop down to ROAS by campaign to find where. - **MER falling as spend rises.** Normal up to a point: it is the marginal cost of scale. The question is whether it is still above break-even. If it is, keep scaling; if not, you have found your current ceiling and the work moves to creative and offer, not budget. - **MER rising while revenue falls.** You are cutting spend and harvesting existing demand. It looks great for a month and you pay for it the following quarter. ## Frequently asked questions ### What does MER stand for in marketing? MER stands for Marketing Efficiency Ratio. It measures how many euros (or dollars) of total business revenue you generate for every unit of currency spent on advertising. It is also known as blended ROAS or aggregate ROAS. ### How is MER different from ROAS? ROAS divides the revenue a platform attributes to itself by the spend on that platform. MER divides total business revenue by total advertising spend. ROAS measures one platform and depends on attribution; MER measures the whole business and doesn't. ### Is a MER of 3 good? It depends on your gross margin. A MER of 3 means 33% of revenue goes on advertising: excellent with a 70% gross margin, ruinous with 25%. The benchmark is always your own target MER, calculated as 1 divided by the share of contribution margin you allocate to acquisition, never another company's number. ### Does MER include agency fees and tools? Most teams calculate MER on media spend only. Others use a variant that adds agency fees, tools and creative production, because that is what acquisition really costs. Either works as long as it is consistent over time and stated clearly when comparing periods. ### Can you have a high MER and still lose money? Yes. MER only looks at revenue and ad spend: it ignores cost of goods, logistics, returns and overheads. A low-margin business can run a MER of 5 and still be losing money. That is why target MER is always calculated from margin and never compared with another company's. ### Is there a benchmark MER by industry? Industry ranges circulate, but they hide margins that vary hugely between businesses in the same sector, so two stores with the same MER can be in opposite situations. Start from your own contribution margin: 1 divided by the share of it you allocate to advertising is the only benchmark that tells you whether your spend pays off. ### How often should you calculate MER? Weekly to read the trend and monthly to set the budget. Daily MER is noise: revenue on any single day depends on too many things that have nothing to do with advertising. ## More resources - [MER vs ROAS: which metric to use and when](https://www.nashmarketinglabs.com/en/blog/mer-vs-roas) - [What is the minimum profitable ROAS (and how to calculate yours)](https://www.nashmarketinglabs.com/en/blog/minimum-profitable-roas) - [ROAS vs ROI: what's the difference and when to use each](https://www.nashmarketinglabs.com/en/blog/roas-vs-roi) - [LTV to CAC ratio: what is a good one and how to calculate it](https://www.nashmarketinglabs.com/en/blog/ltv-cac-ratio) - [The report says ROAS 5. Your best-seller isn't making you a penny.](https://www.nashmarketinglabs.com/en/ecommerce-paid-media-agency) --- Contact: https://www.nashmarketinglabs.com/en/request-audit - Your performance plan: concrete actions to improve your account, no commitment.