Automation

Bid limits

One number that decides the worst a bid mistake can cost you — set once, enforced on every bid MerchDash writes.

Amazon accepts any bid up to $1,000. That is not a safety net anyone wants to rely on: a mis-typed multiplier, a percentage rule that compounds across runs, or one stray zero in a bulk edit can walk a bid somewhere you would never have gone deliberately. A maximum bid is your own ceiling, well below Amazon’s, and MerchDash holds every bid it writes to it.

It turns “a rule went wrong” into “a rule went wrong and cost me my maximum bid”.

Where to set it

Profile → General → Maximum bid. Every field is blank by default, so nothing changes for your account until you fill one in.

The Maximum bid card in Profile → General: a ceiling per ad product with its targeting types nested underneath.
One ceiling per ad product, with the targeting types that can override it nested underneath.

One number per ad product

You set a maximum for Sponsored Products, Sponsored Brands and Sponsored Display separately — the three rarely warrant the same ceiling — and every targeting type under a product follows it. For most accounts that is the entire setup: three numbers, or even one.

Leave a product blank and no maximum of yours applies to it, while the others stay in force. The fields are independent; there is no all-or-nothing.

A tighter ceiling for one targeting type

An ASIN target rarely earns what a proven keyword does, and this is where you say so. Tick a targeting type and give it its own number:

  • Sponsored Products — keywords, product targeting, and the four auto-targeting clauses: close match, loose match, substitutes, complements.
  • Sponsored Brands — keywords and product targeting.
  • Sponsored Display — one maximum for the whole product. Its targets aren’t state-synced, so outside a rule run an audience can’t reliably be told from a product target, and a ceiling that silently failed to apply would be worse than not offering one.

So you can hold substitutes at $0.40 while keywords in the same campaign still go to $1.50.

Two rules keep the tree honest

  • An untouched type shows what it inherits. Raise an ad product and you can see, in the same card, everything that just moved with it.
  • A child can never sit above its parent. Enter a higher number on a targeting type and the ad product rises to match, because it is the ceiling for everything underneath it.

When MerchDash can’t tell which kind of target a bid belongs to — Amazon spells its auto clauses at least three different ways across endpoints, and a report row sometimes names none of them — it applies the strictest ceiling that could apply rather than the loosest. An unrecognised target is capped too tightly at worst, and is never written uncapped.

What it covers

Everything MerchDash writes. There is no path around it:

  • A bid you type into the bid box in Campaigns or on Keywords & targets.
  • The auto-targeting bid dialog, including the fill that computes a bid per clause.
  • Every bulk action that carries a bid.
  • Any bid an automation rule computes — in a preview, a manual run, or a scheduled one. A scheduled run follows the rule owner’s ceiling, so a shared or imported rule can’t bring someone else’s limits with it.
  • The starting bid on a keyword a rule harvests with createKeyword() — a starting bid is a bid.

What it never does

  • It never raises a bid. A ceiling only ever caps; bids under it are written exactly as computed.
  • It never turns a change into a failure. The change is written at the ceiling, not rejected.
  • It doesn’t touch budgets or placement adjustments. This is a bid ceiling and nothing else.

Amazon’s own bounds still apply

Independent of anything you set: bids are written between $0.02 and $1,000, and Sponsored Brands enforce a $0.25 minimum. Amazon’s floor wins over your ceiling — set a $0.10 Sponsored Brands maximum and bids are written at $0.25, with the card and the change note both saying so, because a $0.10 Sponsored Brands bid would simply be rejected.

A bid that is already sitting on a floor isn’t rewritten every run: History shows it as At limit with the reason, rather than an endless trail of changes that change nothing.

Currency

The maximum is one setting for your account, read in each marketplace’s own currency — a maximum of 0.80 is $0.80 in the US and €0.80 in Germany. The card shows the symbol of the marketplace you are currently on.

How you know it applied

A capped change is never silent. It lands in Change history with an Adjusted chip and a note naming both numbers and the exact field that produced it:

$15.00 was capped at your $0.40 substitutes maximum bid (Profile → General).

Leading with the value that was asked for is the point: a rule sitting a cent over its limit and a rule that computed $15 are very different situations, and the gap between the two numbers is what tells them apart. The note names the ceiling that actually applied — the substitutes field, not its Sponsored Products parent — so you know which box to change.

Picking a number

A maximum is a blast radius, not a strategy — it should sit above every bid you would ever set deliberately, not near your target CPC. Start from the highest bid in your account today, add comfortable headroom, and set that. If a rule ever hits it, History tells you which rule and by how much, and that is the moment to decide whether the rule is wrong or the ceiling is too low.

Related: Safety & limits for the other guardrails around a run, and Settings & profile for the rest of the Profile page.