What is MER (marketing efficiency ratio)?
Marketing efficiency ratio (MER) is total net sales divided by total marketing spend. It measures how many dollars of revenue a brand generates for each dollar of marketing across all channels combined. Unlike platform-reported ROAS, MER doesn't depend on attribution, so it shows whether overall spend is paying off.
Formula
Net sales ÷ marketing spend
Example
A hypothetical candle brand has $900,000 of net sales across DTC, Amazon, and wholesale in a month and spends $330,000 on paid media and other acquisition. MER = $900,000 ÷ $330,000 = about 2.7, often written as 2.7x.
How to read it
Higher is better. MER alone doesn't say whether marketing is profitable; what counts as a good MER depends on gross margin and fulfillment costs, which is why it should be read with contribution margin. Because it uses total net sales, wholesale and organic growth raise MER even if paid media isn't improving, and spend that runs ahead of a launch can depress it for a month.
What moves it
- Paid media budget and campaign performance
- Organic, wholesale, and Amazon sales that grow without matching spend
- Promotions that lift sales in a given month
- Creative fatigue and rising ad costs
- Spending ahead of a launch or seasonal peak
What to do when it's flagged
- Check contribution margin to see whether the lower MER is actually unprofitable
- Reallocate budget away from the channels and campaigns with the weakest results
- Refresh creative and offers before increasing spend
- Compare new customer counts and blended CAC to see whether spend is still acquiring customers
How Inflection tracks it
Inflection's KPI Monitor flags MER as Watch below 3.0x and Critical below 2.0x by default; each client's thresholds are adjusted to their business and margin structure.
Net sales and marketing spend come from the QuickBooks P&L, with Shopify sales used for net sales when QuickBooks hasn't been booked for the month.
Related KPIs
Updated 2026-10-11. Example figures are hypothetical.