Should You Use Device-Level Bid Adjustments in Google Ads?
When running Google Ads campaigns, advertisers are always looking for ways to improve efficiency and reduce wasted spend. One feature that often comes up is device-level bid adjustments — the ability to increase or decrease bids depending on whether a user is searching on desktop, mobile, or tablet.
At first glance, this seems like an obvious optimisation tactic. If mobile users convert poorly compared to desktop users, why not simply lower mobile bids?
However, the reality is more complicated.
In this article, we’ll break down:
- What device-level bid adjustments are
- Which bidding strategies allow them
- How Smart Bidding changes the rules
- Whether you should actually use them
- When excluding devices makes sense
- How to apply device bid adjustments in Google Ads
What Are Device-Level Bid Adjustments?
Device-level bid adjustments allow advertisers to increase or decrease bids based on the device a user is using when they click an ad.
For example:
- Increase bids on desktop if desktop users convert better
- Reduce bids on mobile if mobile CPA is too high
- Exclude tablets entirely if they perform poorly
The idea is simple:
Better-performing devices receive more aggressive bids, while weaker-performing devices receive reduced bids.
Historically, this was a common optimisation method in Google Ads accounts.
The Important Limitation Most Advertisers Miss
Many advertisers assume they can apply device bid adjustments regardless of bidding strategy.
That is not true.
Certain Smart Bidding strategies completely restrict device-level bid adjustments because Google already adjusts bids automatically using its own machine learning signals.
This means your ability to control device bids depends entirely on the bidding strategy you are using.
Which Google Ads Bidding Strategies Allow Device Bid Adjustments?
Strategies That Allow Full Device Bid Adjustments
The following bidding strategies allow advertisers to manually increase or decrease bids by device:
Manual CPC
With Manual CPC, you are fully controlling bids yourself, so Google allows complete device-level adjustments.
Example:
- Increase desktop bids by 20%
- Reduce mobile bids by 15%
This directly changes the amount you are willing to pay in the auction.
Maximise Clicks
Maximise Clicks also allows device-level bid adjustments because Google is primarily optimising for traffic volume rather than conversion efficiency.
In both cases, device adjustments are reasonable because Google is not heavily optimising conversion behaviour automatically.
Which Bidding Strategies Restrict Device Adjustments?
Several Smart Bidding strategies do not allow traditional device bid adjustments.
These include:
- Target ROAS
- Maximise Conversion Value
- Target Impression Share
With these strategies, Google automatically adjusts bids based on device and countless other signals behind the scenes.
Because Google’s algorithm is already making those decisions dynamically, manual device adjustments are largely disabled.
The Only Adjustment Allowed
For these Smart Bidding strategies, the only device adjustment available is:
-100% Bid Adjustment
This completely excludes a device from the campaign.
For example:
- Exclude tablets entirely
- Remove desktop traffic
- Prevent mobile ads from showing
Beyond exclusion, no manual percentage increases or decreases are possible.
The Special Case: Target CPA Campaigns
Target CPA campaigns work differently again.
You can apply device bid adjustments with Target CPA, but many advertisers misunderstand what actually happens.
What Google Really Does
The bid adjustment does not directly change your CPC bids at auction level.
Instead, Google adjusts the CPA target itself.
Example
Suppose:
- Your target CPA is £10
- You apply a +40% mobile bid adjustment
Google interprets this as:
- Mobile CPA target becomes £14
So rather than increasing bids directly, you are effectively telling Google:
“I’m willing to accept a higher CPA on mobile devices.”
This is a crucial distinction many advertisers do not realise.
Should You Actually Use Device-Level Bid Adjustments?
This is where things get interesting.
In most modern Google Ads campaigns, device-level bid adjustments are far less important than they used to be.
In fact, in many cases, they can actually hurt campaign performance.
Why Excessive Device Adjustments Can Be Dangerous
The primary issue is volume reduction.
If you aggressively reduce bids or exclude devices entirely, you may lower your CPA slightly — but at the expense of conversions and total lead volume.
For example:
- Mobile CPA may be higher
- But mobile may still contribute valuable conversions
- Removing mobile traffic could drastically reduce overall performance
Modern Smart Bidding systems are designed to balance efficiency and scale automatically.
Overriding those systems too aggressively can limit Google’s ability to optimise effectively.
When Excluding Devices Might Make Sense
There are very few legitimate cases where excluding an entire device category is necessary.
One example mentioned in the video transcript was a taxi and airport pickup company that only accepted phone calls.
The advertiser preferred mobile users because:
- Mobile users could click-to-call instantly
- Desktop users converted less efficiently
Even then, the logic was questionable because desktop users could still manually call the business after seeing the number.
The broader point remains:
Most businesses should avoid excluding devices completely unless there is an extremely strong operational reason.
Why Smart Bidding Usually Knows Better
One of the biggest misconceptions in Google Ads is believing advertisers can out-optimise Google’s machine learning at the device level.
Modern Smart Bidding uses signals advertisers cannot access, including:
- User intent
- Time of day
- Historical behaviour
- Audience signals
- Location
- Browser
- Search context
- Conversion probability
- Cross-device behaviour
Because Google evaluates so many variables simultaneously, manual device adjustments can interfere with more advanced optimisation processes.
That is precisely why Google restricts device adjustments in many Smart Bidding strategies.
When Device Bid Adjustments Do Make Sense
There are still scenarios where device adjustments are appropriate.
Use Device Adjustments When:
You Use Manual CPC
Since you are manually controlling bids already, device optimisation is part of the workflow.
You Use Maximise Clicks
Google is focused on generating clicks, not necessarily conversions, so manual adjustments can help steer traffic quality.
You Have Clear Statistical Evidence
If you consistently see major performance differences by device over a meaningful data set, modest adjustments may help.
Best Practices for Device Bid Adjustments
If you decide to use them, keep these principles in mind:
Avoid Extreme Changes
Small adjustments are usually safer.
Examples:
- +10%
- -15%
- +20%
Huge swings often create instability.
Focus on Overall CPA or ROAS
Do not optimise devices in isolation.
Your goal is overall campaign profitability and volume — not making every device identical.
Let Smart Bidding Learn
If using Smart Bidding:
- Give campaigns time
- Avoid constant manual interference
- Trust the algorithm unless there is overwhelming evidence otherwise
Never Panic Over One Device
It is completely normal for one device category to appear weaker temporarily.
Google often balances performance across devices automatically over time.
How to Apply Device Bid Adjustments in Google Ads
Applying device adjustments is relatively simple.
Step-by-Step Process
1. Open Your Campaign
Navigate to the relevant campaign in Google Ads.
2. Go to “Devices”
Inside the campaign menu, click:
Devices
You’ll see performance segmented by:
- Computers
- Mobile phones
- Tablets
3. Edit Bid Adjustment
Click the bid adjustment column next to the device.
You can then:
- Increase bids
- Reduce bids
- Exclude the device entirely with -100%
4. Save Changes
Click Save and your adjustment becomes active immediately.
Final Thoughts
Device-level bid adjustments are no longer the powerful optimisation tactic they once were.
With modern Smart Bidding strategies, Google already handles much of the device optimisation automatically using far more data than advertisers can access manually.
For most advertisers:
- Manual CPC and Maximise Clicks are the only strategies where device bid adjustments truly make sense
- Smart Bidding campaigns should generally be left alone
- Excluding devices completely is rarely a good idea
- Overall campaign efficiency matters more than device-by-device perfection
The key takeaway is simple:
Focus on your overall CPA or ROAS goals rather than obsessing over individual device performance.
In most cases, Google’s automation will outperform aggressive manual intervention.
