The short answer
A blended marketing efficiency ratio can show total business revenue relative to advertising spend, without trying to assign each order to an ad platform. Here, MER means total store revenue divided by total paid media spend. Some reports use broader marketing costs, so always publish the denominator.
State what is inside the ratio
Campaign ROAS = campaign-attributed revenue ÷ campaign ad spend
Illustrative inputs: a store has $30,000 in net revenue and spends $6,000 on paid media. MER is $30,000 ÷ $6,000 = 5×. A campaign reports $12,000 of attributed revenue from $3,000 of spend, giving $12,000 ÷ $3,000 = 4× ROAS. Neither number replaces the other: the revenue scopes are different.
Why the blended view is useful
It provides a check against a store-level revenue total instead of adding potentially overlapping platform claims. Keep a single revenue source and a complete spend total. Include credits, adjustments, and currencies consistently. If agency, creative, or software costs enter the denominator, call it a broader marketing-cost ratio and show those components.
What MER cannot identify
Total revenue may include organic traffic, email, repeat purchases, or offline activity. A rise in MER does not isolate what the advertising caused. It also cannot tell you which campaign should receive more budget. The ratio can improve when ad spend is reduced even as revenue or contribution declines.
Read the absolute amounts
Using another illustrative scenario, revenue of $24,000 on $4,000 of spend produces 6× MER. Compared with the first scenario’s 5×, efficiency improved while revenue fell by $6,000. To compare contribution, assume the same 40% pre-ad contribution margin in both scenarios. The first leaves $30,000 × 0.40 − $6,000 = $6,000; the second leaves $24,000 × 0.40 − $4,000 = $5,600. The higher ratio leaves less contribution under those assumptions.
Build a paired report
Show blended revenue, paid media spend, contribution after ads, and new-customer counts next to channel ROAS. Use the blended view to ask whether the overall plan is economically coherent, then use campaign and experiment evidence to investigate allocation. Avoid presenting a blended metric as a causal estimate.
Build a paired report
- Gather: Collect unique store revenue, complete media spend and campaign-attributed revenue separately.
- Produce: Place blended efficiency beside campaign ROAS; include absolute contribution in the comparison.
Decision boundary: Never add overlapping platform claims to create the store revenue total.
Next reading
Examples are illustrative, not client results or benchmarks. The calculations use the inputs shown; real-world decisions depend on your records and assumptions. Report a correction.