Paid versus organic on Amazon: how to read your ad dependency ratio and what a healthy one looks like
The share of your sales your ads buy is the most useful number most sellers never compute. How to build it, read it by ASIN and query, and decide yours.
The number that tells you what your ads are really doing
Total sales go up and the ads get the credit. Total sales go down and the ads get the blame. Neither is a reading. The reading is the ratio between ad-attributed sales and total sales, by ASIN, over a window long enough to smooth a promotion. It answers one question: how much of what you sell are you paying to sell?
TACoS, advertising spend as a share of total sales, is the cost cousin of the same idea. The ratio here is about volume, not cost. An account can have a comfortable TACoS and still be buying most of its sales, which means the organic position is thinner than the top line suggests.
How to build it
Two sources. Business Reports give ordered product sales by ASIN. The advertising console, or the advertising reports, give attributed sales by ASIN. Divide attributed by total, per ASIN, per week. Then do the same thing per search query using Search Query Performance for organic standing and the search term report for paid results, because the ASIN-level ratio hides which queries are paid and which are earned.
Watch the attribution window. A sale attributed to an ad clicked several days earlier still counts as paid. That is correct for the ratio's purpose, since the ad started the sale, but it means the ratio moves a few days after the spend moves.
Two ways to read it wrong
The first mistake is treating a high ratio as a failure. A launch is supposed to buy its early sales. A brand entering a query it has never ranked on is supposed to buy its way in. The ratio on a launch should be high and falling. If it is high and flat after months, the ads are renting a position the listing is not earning, and the listing is the problem, not the ads.
The second mistake is treating a low ratio as success. A mature product with a low ratio may be underinvested on queries it could win. The question for a low ratio is whether there is an opportunity query, one with demand and no claimant, that paid spend could turn into an organic position.
What a healthy ratio looks like
There is no universal number, and anyone who gives you one is guessing about your margin. The healthy ratio is the one that leaves contribution margin positive after ad spend on the queries you choose to fight, with the trend moving the right way for the product's stage: high and falling for a launch, low and stable for a mature product on dominating queries, and rising on purpose only when the spend is building a position that organic rank will hold.
The one pattern that is never healthy is paying to reacquire buyers who already chose you. Branded queries with a high paid share, or repeat buyers arriving through ads instead of subscribing, are a ratio problem that looks like growth until the margin is examined.
What to do about yours
Read it per ASIN first, then per query. Move budget off dominating branded queries. Fund opportunity queries and watch conversion before rank. Fix listings where the ratio is high and flat. Revisit weekly, on the same day, from the same reports. If you want an operator to read it with you, start with your MTB Score.