Use marketplace metrics to decide what needs attention, not to decorate a report. ACoS, TACoS, conversion and stock cover answer different questions. Read them together, using consistent reporting windows and definitions, before changing advertising, content or inventory.
The worked examples below use round numbers to explain formulas. They are not client results, market benchmarks or targets. Confirm the reporting definitions available on Amazon, Noon, Trendyol and Carrefour; where a decision depends on platform requirements, check the current rules in the seller portal.
ACoS: advertising cost of sales
ACoS = advertising spend ÷ advertising-attributed sales × 100. It describes advertising spend relative to the sales attributed to that advertising. Check whether the reporting window and attribution basis are consistent before comparing campaigns.
Example: AED 1,000 of ad spend divided by AED 4,000 of ad sales, multiplied by 100, gives ACoS of 25%. This example does not establish profitability. Compare ACoS with the product’s margin before advertising, using compatible sales and cost definitions.
TACoS: total advertising cost of sales
TACoS = advertising spend ÷ total sales × 100. It places advertising spend against all sales in the same scope and reporting period, rather than only advertising-attributed sales.
Example: AED 1,000 of ad spend divided by AED 10,000 of total sales, multiplied by 100, gives TACoS of 10%. A change in TACoS does not prove that advertising caused organic sales. Check the underlying spend, total sales, stock and offer changes before drawing that conclusion.
Conversion: orders relative to sessions
Conversion = orders ÷ sessions × 100, for the order-based definition used here. A session is not necessarily a unique person. Confirm the denominator in the report, because a platform may present a different conversion measure.
Example: 50 orders divided by 1,000 sessions, multiplied by 100, gives conversion of 5%. If conversion changes, inspect traffic relevance, listing accuracy, selected variations, price and availability. Do not automatically respond with a bid change when the offer itself needs attention.
Stock cover: inventory relative to demand
Stock cover = available sellable units ÷ average units sold per day. It estimates how long inventory would last if the selected sales pace continued. Keep reserved, damaged and unavailable units out of the available-stock count.
Example: 600 available units divided by 40 units sold a day gives stock cover of 15 days. This example assumes steady demand. A promotion, seasonal change or recent stockout can make the selected sales pace unsuitable for planning. Compare cover with your actual replenishment requirements rather than using the example as a target.
Read the connections
An availability problem can change sales and advertising behaviour at the same time. A listing correction may alter conversion without a campaign change. Higher advertising spend can affect both ACoS and TACoS. Check what changed in the underlying records before assigning a cause.
Weekly review list
- ACoS: assess ad spend against attributed sales; inspect relevance, cost and margin when it moves.
- TACoS: assess spend against total sales; inspect both totals before inferring advertising impact.
- Conversion: assess orders against sessions; review traffic and the customer offer when it moves.
- Stock cover: assess sellable inventory against sales pace; review replenishment and campaign plans when it moves.
Examples use round numbers to explain a formula. They are not client results.