What is Max Affordable Bid (MAB)?
Max Affordable Bid (MAB) is the highest bid a keyword or targeting option can afford while still staying aligned with your desired ACoS (Advertising Cost of Sales).
Think of it as a profitability guardrail.
Instead of guessing whether a bid is too high or too low, MAB helps determine the maximum amount you can realistically pay for a click based on:
Your product price
Your target ACoS
Your conversion rate
Why is MAB Important?
When bids become too high, advertising costs can increase faster than sales, resulting in poor ACoS.
MAB helps answer a simple question:
"Based on how this product performs, what is the highest bid I can afford and still remain profitable?"
By using MAB, bid automation can:
Prevent overbidding
Maintain profitability targets
Adjust bids dynamically as performance changes
Make smarter bid decisions based on actual account performance
How is MAB Calculated?
MAB is calculated using three key factors:
Average Product Price
Target ACoS
Conversion Rate
Formula:
Max Affordable Bid = Average Product Price × Target ACoS × Conversion Rate
Example
Suppose:
Product Price = $40
Target ACoS = 25%
Conversion Rate = 10%
MAB = $40 × 25% × 10%
MAB = $1.00
In this example, Adbrew estimates that a bid around $1.00 is the maximum affordable bid for maintaining a 25% target ACoS.
What Happens When CPC is High?
Sometimes a keyword may have a relatively low base bid, but the actual CPC being paid is much higher.
This commonly happens when:
Bidding Strategy
Top of Search modifiers are high
Example
Suppose:
Base Bid = $0.70
Top of Search Adjustment = 200%
In this case, Amazon may bid up to:
$0.70 × 3 = $2.10
Even though the base bid is only $0.70, the actual CPC being paid may be much closer to $2.10.
As a result:
ACoS increases
Profitability decreases
The keyword becomes more expensive than it appears
How Does MAB Handle High CPCs?
Rather than looking only at the base bid, Adbrew also considers the relationship between your actual CPC and your current bid.
If the actual CPC is significantly higher than the bid, Adbrew recognizes that the keyword is operating in a more expensive auction environment.
To account for this, MAB is adjusted downward.
In simple terms:
The more expensive your actual clicks become compared to your bid, the more conservative the MAB becomes.
This helps prevent automation from recommending bids that would continue driving unprofitable traffic.
A Simple Analogy
Imagine you have a monthly food budget of $300.
If groceries suddenly become twice as expensive, you cannot keep buying the same quantity of food without exceeding your budget.
You would need to spend more carefully. MAB works in a similar way.
When click costs increase, Adbrew lowers the affordable bid threshold so that your advertising remains aligned with your target profitability.
Key Takeaways
Max Affordable Bid (MAB) is the highest bid a target can afford while staying aligned with your target ACoS.
It is calculated using product price, target ACoS, and conversion rate.
When actual CPCs are significantly higher than the base bid, Adbrew adjusts MAB downward to account for the higher click costs.
This normalization helps protect profitability and prevents automation from recommending overly aggressive bids.
MAB enables smarter, performance-based bid automation rather than relying on static bid values.