Bid adjustments are percentage modifiers that increase or decrease your base bid based on signals like device, location, and audience. A +20% adjustment raises your bid by 20% when that condition matches; a -30% adjustment lowers it. Multiple adjustments stack multiplicatively, so they compound when several conditions apply to the same auction.

In Google Ads, bid adjustments range from -100% (opt out entirely, where allowed) to +900%. They give you granular control over where budget flows without managing separate campaigns for every variable.

How Bid Adjustments Calculate

A bid adjustment is applied to your maximum cost-per-click (CPC) bid before each auction. The math is simple per modifier:

Adjusted bid = Base bid × (1 + adjustment %)

If your base bid is $2.00 and you set a +50% mobile adjustment, your mobile bid becomes $3.00. A -25% adjustment on the same base would drop it to $1.50.

Most teams get this wrong: adjustments don't just add together. They multiply.

How Multiple Adjustments Stack

When a user matches several criteria at once, Google applies each modifier in sequence. Say you have:

  • Device (mobile): +20%
  • Location (California): +10%
  • Audience (cart abandoners): +30%

The combined calculation looks like this:

$2.00 × 1.20 × 1.10 × 1.30 = $3.43

That's a 71.5% total increase, not 60%. The compounding effect can blow past your intended ceiling if you stack aggressive modifiers, so audit overlapping rules regularly.

Diagram showing a base bid passing through device, location, and audience modifiers that multiply into a final adjusted bid

Device Bid Adjustments

Device adjustments let you bid differently across mobile, desktop, and tablet. If mobile converts at half the rate of desktop, lower your mobile bids to protect efficiency. If your landing page is mobile-first and converts well, push mobile higher.

Key points:

  • You can set a -100% adjustment to exclude a device type completely.
  • Tablet was historically grouped with desktop, but you can target it separately in most account setups.
  • Use the Devices report under campaign settings to compare conversion rate and cost-per-conversion before adjusting.

Google's official device bid adjustment documentation covers the current interface and limits.

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Location Bid Adjustments

Location adjustments tune bids by geography: countries, regions, cities, postal codes, or radius targets. High-value metros often justify a positive modifier, while low-performing areas get cut.

Common Location Strategies

  1. Service radius bidding — boost bids near physical locations or service zones.
  2. Revenue-weighted regions — increase bids in states or cities with higher average order value.
  3. Negative adjustments — set -90% on areas you can't fully exclude but want to suppress.

Location modifiers interact with your campaign's location targeting settings. If you target by "presence or interest," your adjustments can apply to users searching about a location, not just those physically there. That distinction matters for both B2B and local campaigns. Sales teams running account-based marketing programs often layer location bids to concentrate spend on target-account headquarters regions.

Audience Bid Adjustments

Audience adjustments modify bids based on who the user is or how they've engaged: remarketing lists, in-market segments, affinity audiences, customer match, and similar segments.

Observation vs. Targeting Mode