Method and assumptions
ACOS measures attributed advertising efficiency, while TACOS shows how advertising spend relates to the entire business. Read both together to avoid optimizing paid sales in isolation.
ACOS = ad spend / ad-attributed sales. TACOS = ad spend / total sales. ROAS = ad-attributed sales / ad spend.
Worked scenario
Use one reporting period and enter ad spend, ad-attributed sales and total store sales. For example, 10,000 USD spend, 40,000 USD attributed sales and 100,000 USD total sales produce different ACoS and TACoS views. Add contribution data before deciding whether either ratio is economically acceptable.
How to interpret the result
ACoS evaluates attributed sales efficiency; TACoS places advertising inside total marketplace revenue. A falling TACoS may indicate organic growth, but it can also result from seasonality, repeat demand or attribution shifts. Compare new-customer volume, total contribution and organic rank or traffic before assigning causality to advertising.
Input reference
- Currency
- Example default: USD
- Advertising spend
- Example default: 2500
- Ad-attributed sales
- Example default: 10000
- Total sales
- Example default: 18000
- Gross margin before ads
- Example default: 40%
Common mistakes
- Using different dates or attribution windows for spend and sales.
- Assuming every attributed order was incremental.
- Optimizing a ratio without a product contribution target.
Before using the result
- Lock the campaign scope and attribution window.
- Compare ACoS with product-level break-even ACoS.
- Use TACoS with total contribution and new-customer trends.
Questions to check before deciding
Why can TACOS be lower than ACOS?
TACOS divides spend by all sales, including non-ad-attributed sales. ACOS only uses sales attributed to advertising.
What is a good ACOS?
There is no universal target. Compare ACOS with the product contribution margin and your growth objective.
Independent calculator. Not affiliated with or endorsed by the platforms mentioned.