# MER

> Marketing efficiency ratio: total revenue divided by total marketing spend.

Source: https://datacenter.so/glossary/mer
Also called: marketing efficiency ratio.

MER = total revenue ÷ total marketing spend, both for the same period. It is sometimes called [blended ROAS](https://datacenter.so/glossary/blended-roas), though some teams count only ad spend in blended ROAS and all marketing costs, such as agency fees, tools and creators, in MER.

Because the revenue comes from your store or payment system, each sale is counted once, whatever channels touched it. That makes MER the honest headline number for "is our marketing paying overall?", while platform ROAS stays useful for comparing campaigns inside one platform. See [ROAS, blended ROAS and MER](https://datacenter.so/guides/roas-mer-blended-roas), and [target MER](https://datacenter.so/guides/break-even-roas-and-target-mer) for the ratio that leaves the profit you planned.

## Related terms

- https://datacenter.so/glossary/roas
- https://datacenter.so/glossary/blended-roas
- https://datacenter.so/glossary/break-even-roas