There is no universal answer, and any single figure presented as an industry standard should be treated with suspicion. The only floor that means anything is your own break even MER, which is 1 divided by your blended gross margin expressed as a decimal. At a 0.40 margin that floor is 2.5. Anything above it contributes to fixed costs and profit, anything below it destroys money regardless of what the ad platform reports.

Is MER the same as blended ROAS?

They are usually calculated the same way, but the intent differs. Blended ROAS often still starts from platform reported revenue and then adds channels together. MER deliberately takes total revenue from your own commerce or accounting system, including orders no ad touched, and divides it by everything you spent on marketing. If your blended ROAS uses platform revenue figures, it is not MER.

Should agency fees and software costs go into MER?

Either choice is defensible as long as you are consistent. Media only MER answers whether the ad buying works. Fully loaded MER, including agency fees, creative production and tooling, answers whether the marketing function works. Pick one, write the definition down, and keep it stable for at least a full year so your trend line stays comparable.

Can MER replace ROAS entirely?

No. MER cannot tell you which campaign, ad set or creative to change, because it never assigns credit to anything. Use ROAS for decisions inside a single channel and MER for decisions about the business. The most useful reporting keeps both on the same screen and treats a growing gap between them as a measurement question worth investigating.

How often should MER be calculated?

Weekly for direction and monthly for decisions. Weekly MER is noisy because promotions, paydays and delivery cycles move revenue around, but it catches a collapse early. Monthly MER is stable enough to act on. Whichever cadence you choose, always compare the same length of period, since a four week month and a five week month are not comparable.

Marketing efficiency ratio: what is MER?

The question comes up in almost every scaling conversation: what is MER, and why does the finance team trust it more than the ROAS sitting inside Ads Manager? MER stands for marketing efficiency ratio. It is your total revenue divided by your total marketing spend over the same period, across every channel, with no attribution logic anywhere in it. You can calculate it from your bank statement and your store dashboard alone. That is the entire reason it exists.

The formula, worked through once

MER equals total revenue divided by total marketing spend. Both numbers come from the same date range, both are account level rather than campaign level, and neither one is supplied by an ad platform.

Say your store recorded 500,000 in revenue last month and you spent 100,000 across Meta, Google, agency fees and everything else you would honestly call marketing. 500,000 divided by 100,000 equals 5. Your MER for the month was 5. Run those same two numbers every month and you have a trend line that no platform update can quietly rewrite. If you would rather not maintain the spreadsheet, the MER calculator does the same arithmetic and keeps the inputs visible.

Notice what is absent from that calculation. No pixel. No attribution window. No modelled conversions. No argument about whether Meta or Google deserves credit for the same order. MER never asks which ad won, so it can never get that answer wrong.

So what is MER measuring that ROAS is not

ROAS answers a narrow question well: for the conversions this platform believes it caused, how much revenue came back per unit of spend? That is genuinely useful when you are comparing two ad sets inside one account. If the definition itself is still fuzzy, our explainer on what ROAS is and how to calculate it covers the campaign level view in detail.

The trouble starts when you add the platforms together. Reported ROAS is a self assessment. Each platform decides what it caused, using rules it wrote, measured with data it collected. Sum those self assessments across three channels and you get a number that describes nobody's actual business.

Three places the gap opens up

Double counting. A customer sees a Meta ad on Monday, searches your brand name on Wednesday, clicks a Google ad and buys. Both platforms can legitimately report that order. Your accounting system records it once.
Attribution windows. Platforms let you choose how long after a click or a view a conversion still counts. Meta and Google both publish their attribution settings in their official documentation, and defaults change over time, so verify which window your account is actually reporting on before you compare two months to each other.
Demand you would have captured anyway. Branded search, returning customers and organic traffic all sit inside somebody's reported ROAS. Untangling that is an attribution project in its own right, and our piece on multi touch attribution walks through the models people use to try.

MER absorbs all three problems by refusing to model any of them. The cost is that it tells you nothing whatsoever about which campaign to turn off.

Use both, for different decisions

Inside a channel, use ROAS. Two ad sets, same objective, same attribution window: the platform's own comparison is the right tool for that job.
Across the business, use MER. Budget shifts between channels, monthly profitability, anything you present to an investor or a board.
When they disagree, believe MER. If reported ROAS holds steady while MER slides, the platforms are claiming credit for revenue that was already on its way.

Setting a MER floor from your own margins

A MER of 5 means nothing on its own. Whether it is good depends entirely on what is left after the cost of goods.

Work it backwards. Take your blended gross margin as a decimal, using your own figure rather than any published average. If that margin is 0.40, your break even MER is 1 divided by 0.40, which is 2.5. Below 2.5 you are buying revenue that loses money before a single fixed cost is paid.

Now hold the earlier example against that floor. Revenue of 500,000 at a 0.40 margin leaves 200,000 of gross profit. Subtract the 100,000 of marketing spend and 100,000 remains to cover salaries, rent, software and profit. Whether that is comfortable is a question for your own profit and loss statement, not for a benchmark table.

Blended MER hides your next decision

Blended MER is a rear view mirror. The number that matters when you are scaling is the marginal one: what did the last increment of spend actually return?

Run it across two months. Month one is 100,000 of spend and 500,000 of revenue, so MER is 5. Month two is 140,000 of spend and 560,000 of revenue. Blended MER is 560,000 divided by 140,000, which is 4, and that still reads as respectable. But the extra 40,000 of spend produced 60,000 of extra revenue, so the marginal ratio is 60,000 divided by 40,000, which is 1.5. At a 0.40 margin that increment lost money while the blended figure stayed reassuring.

Calculate the marginal figure every time you raise budgets. It is the earliest honest signal that a channel is saturating, and it is why scaling decisions belong to a rule you set in advance rather than to a good week. The auto scaling page sets out how we think about budget changes on Meta and Google Ads.

What actually moves MER

Because MER is revenue over spend, only two levers exist, and one of them is usually ignored.

Raise revenue per order. Average order value, bundles and post purchase offers lift the numerator without touching media cost at all.
Raise repeat purchase rate. Second and third orders arrive with no new acquisition cost attached, which is why a brand with strong retention can run a lower first order ROAS and still show a healthy MER.
Fix the site before the media. A conversion rate improvement multiplies through every channel at once, which media buying never does.
Cut spend that produces nothing. Exhausted creative, overlapping retargeting and placements nobody chose all sit in the denominator whether or not they sold anything.

How to start this week

Agree the definition of marketing spend with whoever owns the budget: media only, or media plus tools, agency fees and creative production. Write it down and do not change it mid year.
Pull total revenue from the system you invoice from, never from an ad platform.
Calculate MER weekly and monthly. Weekly shows reaction, monthly shows truth.
Record your break even MER next to the actual figure so the comparison is always in view.
Add the marginal calculation whenever you change budgets by a meaningful amount.

Once those five habits are in place, MER stops being a reporting metric and becomes the number that decides whether you spend more tomorrow. That is a very different job from the one ROAS was built to do.