The TOS modifier goes up to 900%. Sounds like a power tool. It's usually a grena
By Anthony Nguyen 🟢 · July 5, 2026 · Curated by George's Blog
The TOS modifier goes up to 900%. Sounds like a power tool. It's usually a grenade.
Here's the math most sellers miss. Your effective bid for Top of Search = base bid x (1 + TOS modifier%). A $1.00 base bid with a 200% modifier = $3.00 effective TOS bid. Straightforward.
Now the dangerous part. If you're running "dynamic bids, up and down," Amazon can increase your bid by up to 100% on top of the modifier. That $3.00 becomes $6.00. From a one-dollar base bid.
With a 900% modifier? Your effective TOS bid = $1.00 x 10 = $10.00. Add dynamic bidding up, and Amazon can push that to $20.00. Twenty dollars. From a one-dollar base bid.
But the real problem isn't the TOS bid. It's what happens to everything else.
Your base bid ALWAYS applies to Rest of Search. If you set a low base bid to control your TOS effective bid, you're starving ROS and product page placements. Want a $5.00 TOS bid with 900% modifier? Your base bid is $0.50. That's what you're bidding on ROS. You'll get almost zero impressions outside TOS.
If TOS inventory runs out or your quality score drops, the campaign goes silent. Completely.
The better approach: moderate modifiers (100-300%) with a base bid that still competes on ROS. A $1.50 base with 200% modifier gives you $4.50 TOS and $1.50 ROS. Both placements stay active.
Use "dynamic bids, down only" when running TOS modifiers above 200%. You keep the placement control without giving Amazon a blank check.
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