There's a lot to consider when setting and adjusting MACS, here is a quick list of what to do and more importantly, what not to do. 

What to do:

  1. Set MACS based on campaign goals and where the products are in their lifecycle: profit vs launch, seasoned product vs new product 

  2. Consider category competition: higher MACS are needed for categories with lots of sellers

  3. Set MACS no lower than 10% of campaign ACoS 

  4. Review MACS (and bid change history) every 2-3 weeks, making changes where necessary

  5. Set the "Bidding Strategy" in Seller/Vendor Central to: 'dynamic bids - down only'

  6. Be patient. Data collection takes approximately 30 days, for low volume sellers, expect this time period to be longer 

What NOT to do: 

  1. Do not set MACS more 10% lower than current campaign ACoS

  2. Do not make frequent changes to MACS: more than once in 1-2 week period 

  3. Do not reduce MACS more than 10%-15% at a time

  4. Do not reduce MACS during the discovery stage 

  5. Do not use Bid Floors for an extended period of time (over 2 months)

  6. Do not set MACS below 40% for newly launch campaigns (no data)

  7. Do not set MACS on campaigns that house ad groups with different goals/objectives

  8. Do not make manual adjustments to bids in Seller/Vendor Central

  9. Do not set Bidding Strategy in Seller/Vendor Central to 'dynamic bids - up and down' or 'fixed bids'

  10. Do not use 'Adjust bids by Placement' booster in Seller/Vendor Central

Next: Using the MACS Calculator

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