MER
Whether the whole business is buying its sales at a price you can live with.
What it means
MER is your Ad Spend divided by your Order RevenueOrder Revenuerefunds and costs not taken off. Expect it above your other sales figures, and never read the difference as profit., written as a percentage: the share of everything your orders were worth that went back out on advertising. It measures every connected ad channel against all order revenue, not one platform against the sales that platform claims, so no attribution decision touches it.
Lower is better here, and that is the opposite of the usual convention. Elsewhere MER normally means sales divided by spend, where 3.0 is healthy and bigger is better. In this app it's spend divided by revenue, graded excellent at 30% and poor at 45%. Read a 42 as a strong month and you have read it upside down. ROASROASCounts only sales Amazon credits to these ads, not your whole Amazon business. Compare it against your product margin before deciding a campaign is paying4 or more is healthy is the right-way-up version of the same two numbers.
Show the math
Formula and a worked example
Ad SpendAd Spendother channels sit elsewhere. Rising spend is fine only if sales and the return keep pace. is every connected ad channel added together for the period — Meta, Google, TikTok and AppLovin, with Amazon included on Summary when Include Amazon is switched on.
Order RevenueOrder Revenuerefunds and costs not taken off. Expect it above your other sales figures, and never read the difference as profit. is what your orders were worth over the same period — item price × quantity, less discounts, plus shipping and tax. Because it counts tax and shipping, it sits above your Total Sales line, so this reads lower than a spend-over-sales figure would.
It reads as a percentage and lower is better. 25% means twenty-five cents in every euro of order value paid for the advertising.
Worked example. March Order Revenue is €62,000 of item value, less €5,000 of discounts, plus €6,000 of shipping and €9,000 of tax — €72,000 in all. Ad Spend is €18,000. MER = 18,000 ÷ 72,000 = 25%. The ROAS card on the same page reads 72,000 ÷ 18,000 = 4.0. One fact, written two ways — if you have read both cards, you have read one number.
Nothing in this is attributed, and that cuts both ways. No platform can inflate it by crediting itself, and it will never tell you which platform earned what.
It answers the question
How much of your order value went on advertising? At 25% the answer is twenty-five cents in the euro, and the next question is whether the other seventy-five cover product, fees, shipping and the rest of the business with something left over.
Why it matters
It's the one advertising number no platform can flatter. Every attributed metric depends on a platform deciding which sales were its doing, and every platform decides generously. MER divides one bill by one revenue figure, and you can check both against your own orders.
That also makes it the number to build a budget from. Decide the MER you're willing to run at and next period's spend follows from your revenue forecast rather than from last period's habit. The published band is a starting point, not the limit — the real ceiling is your own margin, because whatever MER you run has to fit inside what's left after product cost, fees and shipping.
What good looks like
Lower is better, so the healthy end of this scale is the left one. Expect this card and the ROASROASCounts only sales Amazon credits to these ads, not your whole Amazon business. Compare it against your product margin before deciding a campaign is paying4 or more is healthy card beside it to disagree at the edges: 30% here is a ROAS of 3.3, while ROAS is graded excellent at 4 — which would be 25% here. Two bands, one number, and neither is the threshold that decides anything. That one is your margin.
How to improve it
| Lever | What you do | Expect | How long | Watch out for |
|---|---|---|---|---|
| Fast Cut the spend that never became a sale | Sort campaigns by spend, look across at the sales column, and pause the rows with spend and no orders over two full weeks | MER down, spend down | 1–2 weeks | You improved the ratio by shrinking. Order Revenue usually falls with it, so read the revenue line beside the ratio or a retreat reads as a win. |
| Fast Move budget to the channel carrying the period | Compare each channel's spend against the sales in the same period, then reset the daily budgets | The same total spend against a lower MER | 1–2 weeks | Concentrating budget makes the whole business depend on one platform's pricing. The month it turns expensive, there's nowhere left to move to. |
| Slow Sell more to the customers you already have | Work the email and SMS lists and the repeat purchase, so sales arrive without a media bill behind them | Order Revenue rises while Ad Spend holds flat | 1 quarter | Sending harder to hit the number costs list health, and an unsubscribe is permanent in a way a bad ad week never is. |
| Slow Fix what the paid traffic lands on | Improve the product pages and checkout your ads point at, so the same spend turns into more revenue | MER falls with no budget change at all | 1 quarter | Site work never shows up in an ad account, so the gain gets credited to whatever budget change happened the same week — and the wrong lever gets pulled again next quarter. |
Every lever costs something somewhere. The last column is the one to read twice.
Read it with
A ratio improves when the top falls or when the bottom rises, and those are opposite situations. Read it against revenue or you can't tell growth from retreat.
Scaling efficiently
More revenue for a smaller share of it spent. The rare corner, and the one worth pushing into before whatever caused it goes away.
Bought the growth
Revenue is up and a bigger slice of it paid for the ads. A decision rather than a fault, as long as the slice still fits inside your margin.
Cheaper and quieter
A better ratio on less revenue usually means less advertising, not better advertising. This is the corner where stores under-invest and congratulate themselves.
The real alarm
Less revenue and a larger share of it going to ads. The cause sits outside the ad accounts as often as inside them, so check the site before the bids.
The ratio moves for two different reasons and only the spend line says which. MER climbing while Ad Spend sits flat means the money is doing less than it was, and no budget decision caused it. MER climbing alongside spend means you chose this — the only question left is whether you'd choose it again.
On Marketing these two divide the same pair of numbers in opposite directions, so they can never disagree about direction — only about where the line sits. 30% here is a ROAS of 3.3, and ROAS grades excellent at 4. When one card says excellent and the other doesn't, you're looking at two bands, not two findings.
Common misreads
Not in this app. Here MER is Ad Spend ÷ Order Revenue as a percentage and lower is better, so 42% is nearly at the poor band of 45%. The convention you're thinking of divides sales by spend, and ROAS is the card that does that.
The denominator is all your order revenue, including the repeat orders and organic traffic no ad ever touched. A store with a strong list and loyal customers can post a healthy MER while its advertising earns very little. This is a measure of the business, not of a campaign.
It never will. Meta divides only its own spend into only the sales it claims; MER divides every channel's spend into all your order revenue. It won't match any single ad platform, and that is the point — one honest figure the platforms can't each inflate.
The warning only appears when Meta, Google, TikTok Ads and AppLovin are all disconnected. One live channel is enough to hide it, so a single dropped connection can quietly drag MER down without a prompt. Check Integrations if a channel's spend looks missing.
Also called
Marketing Efficiency Ratio · media efficiency ratio · blended marketing efficiency · ad spend as a share of revenue
See yoursYour MER for the period, next to the Ad Spend and the Order Revenue it divides.
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