What is MER in marketing?
MER, or marketing efficiency ratio, is your total revenue divided by your total marketing spend over the same period. It is also called blended ROAS, because it blends every channel into one number instead of judging each platform on the sales it claims.
A MER of 4 means every $1 you spent on marketing came with $4 of revenue across the whole business: ads, email, organic search, word of mouth and repeat customers.
The MER formula
Use "Find total marketing spend" above to see what you can spend for a revenue target at the MER you need, or "Find total revenue" to see what a budget should bring in at your usual MER.
Worked example
Last month your store made $50,000 in revenue. You spent $8,000 on Meta, $3,000 on Google and $1,500 on TikTok.
Planning: to reach $80,000 next month at the same MER of 4, you can spend about $80,000 ÷ 4 = $20,000 on marketing.
What to count as revenue and spend
MER is only useful if you count the same way every month. Pick one definition and keep it:
- Revenue: total store sales for the period, from your store (Shopify or similar), not from the ad platforms. Decide once whether you use gross sales or net of refunds and discounts.
- Spend: every paid channel (Meta, Google, TikTok and the rest). Many brands also add creator and influencer fees, agency fees and creative production, because they are part of what it costs to sell.
- Period: the same dates for both. A week is noisy; a month is the usual view.
MER vs ROAS
- ROAS = revenue a platform attributes to its ads ÷ that platform’s ad spend. Meta, by default, counts sales within 7 days of a click or 1 day of a view.
- MER = all revenue ÷ all marketing spend. Nothing is attributed, so nothing is counted twice or missed.
- Use ROAS to compare campaigns, ad sets and ads inside one platform. Use MER to check whether your marketing as a whole is paying off.
When the platforms together claim more sales than your store actually made, the sum of their ROAS looks better than reality. MER shows the real total. When MER falls while platform ROAS holds, look at attribution before you cut budgets.
Your break-even MER
A MER is only good or bad compared with your margins. Your break-even MER is the point where gross profit exactly pays for marketing:
Above your break-even MER, marketing leaves profit to cover the rest of the business; below it, every dollar of marketing loses money before rent, salaries and software. Count shipping and payment fees in your margin. Find it with the profit margin calculator.
What is a good MER?
There is no single good number, because it depends on your margin and on how much of your revenue comes from returning customers. A brand with a 70% margin can grow at a MER of 2, while a brand with a 30% margin loses money below 3.3. Start from your break-even MER, then decide how far above it you need to be to cover fixed costs and leave profit.
Repeat customers raise MER over time, because their orders arrive with little new spend. If you are spending to win new customers who will buy again, a MER close to break-even can still be worth it. See what a customer is worth over time with the LTV calculator.
How to raise your MER
- Better creatives: a stronger hook lifts CTR, which lowers CPC and CPA, so the same spend brings more sales.
- Higher order value: bundles, upsells and free-shipping thresholds raise revenue per order without more spend.
- More repeat revenue: email, SMS and subscriptions add revenue that costs little marketing.
- Cut spend that stays below break-even after a fair test, on every channel, not only the one you look at most.