Device targeting is the set of controls in Google Ads that decides how much you bid, or whether you show at all, when someone searches or browses on a computer, a mobile phone, a tablet or a TV screen. On Search campaigns it mostly takes the form of a device bid adjustment: a percentage that raises or lowers your bid for one type of device.
How device targeting works
Google recognises four device types: computers, mobile phones, tablets and TV screens. In a Search campaign every device is included by default, and you change how hard you compete on each one with a bid adjustment. A +20% adjustment on mobile turns a £2.00 manual bid into £2.40 for phone searches; a -100% adjustment stops the ads showing on that device altogether.
How much those percentages matter depends on your bidding. With manual CPC they are applied exactly as you set them. With Smart Bidding, Google already weighs the device in every auction, so any adjustment other than -100% is ignored. Only the exclusion still holds. Display and video campaigns go further and let you choose operating systems, specific device models and mobile networks.
Performance Max and some other automated campaign types give you far fewer device controls. At the time of writing (October 2026), Google has been adding limited device options to some of them, so check the settings tab of each campaign rather than assuming the same controls exist everywhere.
Why it matters for a UK business
The same search can mean something different depending on the screen. Someone typing “emergency locksmith” on a phone at 11pm in Hackney wants a number to call now. Someone researching “payroll software for small business” on a laptop in an office is comparing options and may fill in a long demo form. If your offer, your landing page or your phone line only suits one of those situations, paying the same for both wastes money.
Device data also exposes problems that are not about bidding at all. When phone conversion rates are far below desktop, the cause is often a slow page, a form that is painful on a small screen or a phone number that is not tappable. Raising or lowering bids hides that rather than fixing it.
Bear in mind that people switch screens. A visitor may click your ad on a phone during the commute and buy on a laptop that evening. Google reports some of these journeys as cross-device conversions, so judge each device on the conversions credited to it, not on where the sale finally happened.
Common mistakes
- Setting device bid adjustments on a Smart Bidding campaign and assuming they are doing something.
- Excluding mobile because its last-click conversion rate looks weak, then watching desktop sales fall because phone visits were starting those journeys.
- Judging devices on a few weeks of data with a handful of conversions each.
- Fixing a broken mobile landing page with lower bids instead of fixing the page.
- Forgetting that tablets and TV screens are switched on by default and never checking them.
How to act on it
Open the Devices report in Google Ads (under Insights and reports, or the campaign’s Devices view) and compare cost, conversions, cost per conversion and conversion value for each device over a period long enough to hold meaningful numbers. Then decide what kind of problem you have.
- If you use manual CPC, set adjustments that reflect the real difference in value per click between devices, and revisit them each quarter.
- If you use Smart Bidding, leave the percentages alone. Use exclusion only when a device genuinely cannot convert, such as a desktop-only software download promoted to phones.
- If one device converts badly, test the landing page on that device first: load speed, form length, tap targets and click-to-call.
- For phone-led businesses, pair mobile traffic with call assets and opening hours so people can ring while you are there to answer.
Reviewing device performance is one of the routine checks in the Google Ads management I do each month, alongside location and schedule settings.