The two ratios answer different questions
ACOS is ad spend divided by ad-attributed sales. TACOS is ad spend divided by total sales for the same product and period. ACOS is useful for campaign efficiency, while TACOS provides a broader view of advertising intensity across paid and organic demand.
Read the direction before judging the number
- Falling ACOS with stable sales can indicate improving paid efficiency.
- Falling TACOS with growing total sales can indicate that organic sales are contributing more.
- Rising TACOS can be reasonable during a launch, but it needs a time limit and profit budget.
- Low ACOS is not automatically good if campaigns are missing valuable demand and total profit is shrinking.
Keep attribution limits in mind
Ad-attributed sales and total sales use different measurement logic. Use consistent date ranges and avoid assuming every organic sale was caused by advertising. Treat the pair as diagnostic indicators, then confirm the result in SKU-level profit and unit trends.
Create a weekly four-metric view
Review ad spend, ad-attributed sales, total sales, and contribution profit together. This keeps campaign optimization connected to the business outcome and prevents either ratio from becoming the only definition of success.