TACoS (total advertising cost of sales) is ad spend divided by all sales, not just the sales attributed to ads. Spend $300, sell $3,000 in total, and TACoS is 10%.
Why it matters
ACoS can look healthy while the account quietly becomes dependent on ads. TACoS catches that. When TACoS falls over time while sales hold or grow, organic rank is doing more of the work. When TACoS rises while ACoS stays flat, ads are replacing organic sales rather than adding to them.
What a good TACoS looks like
There is no universal target. A launch can run at 25% or higher for a few weeks on purpose. A mature product with strong rank often settles between 5% and 12%. The trend matters more than the level: the direction over 8 to 12 weeks tells you whether the strategy is working.
How we use it
TACoS is the headline number in our weekly report because it connects advertising to the whole business. It is the metric behind our organic-shift strategy, where the goal is to earn rank with ads and then let organic sales carry a growing share.