MER = total revenue ÷ total marketing spend
$84,000 ÷ $13,000 = 6.46
Why add up the whole business instead of each channel?
Because each ad account counts the sales it touched, and many sales are touched by more than one. A customer who saw an Instagram ad, later clicked a Google Shopping ad, and then bought from an email can be counted by Meta, by Google and by the email tool, all for one order. Add up what each one reports and the total is often bigger than the shop's real sales. MER sidesteps the argument: one revenue figure from your store or your accounts, one spend figure from your invoices.
How much did each marketing dollar bring a Bendigo kids' clothing shop? (example figures)
An online kids' clothing shop run from Bendigo looked at one month. The owner wrote down what each channel claimed, then the store's real total.
| Channel | Spend | Sales the channel claims | ROAS it reports |
|---|---|---|---|
| Meta | $6,000 | $38,000 | 6.3 |
| Google Ads | $5,500 | $41,000 | 7.5 |
| Email tool | $300 | $15,000 | 50 |
| Influencer gifting | $1,200 | no tracking | unknown |
| Claimed total | $13,000 | $94,000 | |
| The store's actual sales, no GST, after refunds | $13,000 | $84,000 | MER 6.46 |
The channels claimed $10,000 more than the shop sold, and that is before counting the customers who typed the address in or came from a friend's recommendation, who got credited to nobody. Not one of those reports is lying by its own rules; each one counts the orders it can see. The MER of 6.46 is the only figure on the page where every dollar is counted once.
At a 48 percent gross margin, the shop's floor is 1 ÷ 0.48, an MER of 2.08, so 6.46 leaves plenty of room. The owner now tracks MER monthly and reads each channel's ROAS for direction only.
What can MER not tell you?
Which channel to cut. MER moves when anything moves: a good month of word of mouth lifts it, a supplier delay drops it, and neither has anything to do with the ads. It also includes sales from loyal customers who would have bought with no marketing at all, so a business with a big repeat base can show a strong MER while its new customer ads lose money. Some shops track a second version using only first-time customers' revenue for that reason. Use MER as the check on the whole, and test a single channel by pausing or changing it and watching the MER over the following weeks.
How does CoraVision help with the blended number?
CoraVision reads spend from Google Ads and Meta every night, and from Google Analytics 4 it reads purchases and revenue, which gives the two sides of a blended ratio for the sales your website tracked. Your store's own total is the truer top line, because GA4 counts only what its tag sees. Your Trust Score on the CoraVision dashboard says how far those tracked numbers can be relied on, which is the first thing to check when channels disagree.
Questions
Is MER the same as blended ROAS?
Yes, two names for one sum. Blended ROAS is the name people use when they want to compare it with the ROAS each ad account reports. MER is the name used when it is tracked as a business figure, month on month.
What MER should a shop aim for?
Start from your own floor: 1 divided by your gross margin is where marketing pays for the stock it sells and nothing else. The rent, wages and profit also have to come out, so the working target sits above that. A shop with a 50 percent margin breaks even at an MER of 2.
Does email software count as marketing spend?
Yes, along with anything else you pay only because you market: the email tool, influencer gifting, an agency fee, a photographer for product shots. Leave them out and the MER looks better than the business is doing.