TACoS measures advertising spend against total Amazon sales. It is useful for judging how much of the business's revenue advertising consumes, provided marketplace, time period, product scope and revenue basis match. It cannot establish whether ads caused incremental growth.
Calculate TACoS consistently
TACoS = advertising spend ÷ total Amazon sales × 100.
A business with €8,000 ad spend and €100,000 total Amazon revenue has 8% TACoS. Include a consistent set of ad formats in the numerator and a matching product portfolio in the denominator. Never divide by zero. Document whether sales include VAT, returns and discounts.
ACoS uses ad-attributed sales instead. Attribution can cross reporting dates and products, so subtracting attributed sales from Business Reports sales does not automatically produce a clean measure of organic revenue.
Why a falling TACoS can mislead
A lower ratio may reflect stronger non-ad demand, seasonal traffic, a higher price or reduced spend. It may also hide weaker acquisition and declining absolute profit. Check the mechanism before presenting the decline as an achievement.
Review the portfolio, then the product groups
Pair TACoS with absolute contribution, total sales, ad spend, stock availability and changes in product mix. A high-margin product can support a different spend level from a low-margin line. Portfolio averages hide that difference.
Use comparable periods and annotate promotions, price changes and stockouts. If TACoS rises, identify whether spend increased or sales declined. The first may be a deliberate acquisition test; the second may come from a lost offer, a weaker delivery promise or a conversion issue.
Make the next action explicit
A weekly review should end with an owner and a decision: restore availability, inspect a high-spend query group, test content or hold the budget until attribution matures. Avoid a universal TACoS target disconnected from margin and growth objectives.
Read Business Reports for revenue decomposition and Search Query Performance for query-level diagnosis. Our PPC team connects advertising metrics with product economics.
