Why does ACOS differ between Amazon Ad Center and MerchantSpring?

It’s common to see differences in ACOS between Amazon Ad Center and MerchantSpring. This is primarily due to how advertising sales are attributed across products.

How Amazon Calculates Ad Sales

Amazon attributes advertising sales in two ways:

• Same-SKU Sales
  Sales where the customer clicks an ad and purchases the exact product advertised
• Cross-SKU Sales
  Sales where the customer clicks an ad but purchases a different product (e.g. another variation, size, or related SKU)

Amazon Ad Center includes both types of sales when calculating ACOS.

How MerchantSpring Calculates Ad Sales

MerchantSpring reflects these differently depending on the report:

Advertising Module (Products Report)

• Includes total attributed ad sales (same-SKU + cross-SKU)
• This aligns closely with Amazon Ad Center

Product-Level Sales Reporting

• Attributes sales only to the specific SKU shown in the report
• Does not include cross-SKU attributed sales

Why You’re Seeing Different ACOS Values

For example:

• Amazon Ad Center
  ~$5K ad sales / ~$2.2K spend → ~44% ACOS
  (Includes all attributed sales)
• MerchantSpring (Product-Level View)
  ~$2.1–2.2K ad sales / ~$2.2K spend → ~99% ACOS
  (Same-SKU only)

Both are correct — they’re just measuring different things.

Which One Should You Use?

• For advertising decisions (e.g. scaling spend):
  → Use the Advertising Module (Products Report)
  → This reflects total campaign impact, consistent with Amazon
• For product-level analysis:
  → Use product-level reporting
  → This helps understand organic vs advertised performance for that specific SKU

Notes:

• Differences in ACOS are expected when comparing across different report types
• Always ensure you are comparing like-for-like attribution models
• Advertising metrics may also vary slightly due to timing and attribution windows