What is MER?

MER — marketing efficiency ratio — is the simplest read on marketing spend: total contribution margin earned on your own store, divided by ad spend on your own-store ad channels, for the same month. Marketplace sales are left out of the margin, as marketplace ad spend is left out of the spend. There is no per-order attribution model in between — no first-touch, no linear split — so it does not depend on which channel gets credit for which sale.

Formula

MER = own-store contribution margin ÷ own-store ad spend

Worked example

In a given month, the store earns €180,000 of contribution margin across every own-store order (not just orders linked to an ad) and spends €50,000 across its own-store ad channels. MER is €180,000 ÷ €50,000 = 3.6×. A channel-level true ROAS could read higher or lower than this for any individual channel; MER is the org-wide backstop figure.

How Saldo Metrics computes it

canonical.v_channel_mer computes two figures per month: mer, and the one this page covers, blended_mer. Both start from the same two totals — total_margin_eur, the sum of contribution_margin_base from v_contribution_margin across every own-store order that month (store views with channel_type = 'own_store'), and total_spend_base, the sum of spend_base from v_ad_spend_enriched across every own-store ad channel that month — marketplace ad spend such as Amazon Ads is left out. Marketplace orders are left out of the margin side the same way: own-store ad spend did not buy them. blended_mer is total_margin_eur ÷ total_spend_base directly. (mer, the per-channel column in the same view, instead allocates a channel's share of that total margin in proportion to its share of total spend, then divides by its own spend — a proxy, not an attribution result, since v_channel_mer has no per-order journey data to work from. blendedMer — the key this page owns — reads only the org-wide blended_mer value.)

As with true ROAS, total_margin_eur excludes cancelled orders and orders refunded in full — MER counts contribution margin from completed sales only, the same definition used everywhere else contribution margin is reported.

Why it matters

MER answers "is marketing spend working at all," without requiring an attribution model to be right. It is the number to watch when deciding whether to grow or shrink the ad budget overall; true ROAS and the attribution model comparison answer where that budget should go.

Common mistakes

  • Chasing MER up by cutting a small, marginal channel without checking whether that channel was acquiring customers a larger channel can't reach — MER has no channel detail by construction, that's what true ROAS is for.
  • Comparing MER month over month without checking spend timing. A month with a large one-off promotional push shows lower MER even if the marginal spend was efficient, because MER is a same-month ratio, not a matched cohort of spend and the revenue it eventually drove.
  • Treating a single month's MER as the trend. Look at the monthly series, not one point.

Where you see this in the app

Marketing → Overview, in the blended MER figure at the top of the tab.