Glossary
Marketing efficiency ratio (MER)
All your revenue divided by all your marketing spend over the same period, whichever channel claims the sale.
Formula
MER = total revenue ÷ total marketing spend
Worked example
A month with £250,000 of revenue and £50,000 spent across Meta, Google and email tools has an MER of 5.
In fashion, footwear and sportswear
Read MER by market as well as for the store. A strong home market can hide a new country where spend runs well ahead of sales.
Where it misleads
MER counts returning customers who would have bought anyway, so it flatters an established brand. Use net sales after returns, and keep the spend definition the same month to month.