Mobile and desktop in GA4: find where phones lose enquiries

Key takeaways

GA4 mobile vs desktop comparison is the quickest way to find out whether your mobile site is losing enquiries. The device report takes two minutes to open. Four numbers, read side by side for phones and computers, show whether the problem is traffic, engagement or the final step, and which page to look at first.

• Find it under Reports, Tech, Tech details, with device category selected.
• Compare share of sessions, engagement rate, key events and key event rate.
• Mobile converting at under half the desktop rate usually signals a mobile problem.
• Break the gap down by landing page before deciding what to fix.

Where is the device report in GA4?

In Google Analytics 4, open Reports, then Tech, then Tech details, and change the primary dimension to Device category. The table shows users, sessions, engagement and key events for mobile, desktop and tablet. Set the date range to the last 90 days so one campaign or holiday week does not distort the picture.

For a side-by-side view on any other report, use the comparison feature at the top of the page: add a comparison where device category is mobile and another where it is desktop. Every chart and table then shows both.

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Which four numbers should you compare?

Four numbers tell most of the story. Read each for mobile and for desktop, then look at the ratio between them. The absolute figures matter less than the gap.

• Share of sessions: how much of your traffic is on each device.
• Engagement rate: the share of sessions that lasted, converted or viewed a second page.
• Key events: enquiries, calls, WhatsApp taps, bookings or orders.
• Session key event rate: the share of sessions that included a key event.

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How do you read the gap?

Mobile will usually convert lower than desktop, so do not expect parity. A working rule is that mobile converting at less than half the desktop rate points to a mobile experience problem. Where mobile engagement is also much lower, the trouble starts on arrival. Where engagement is similar but conversion is low, it starts at the form, the call button or the checkout.

• Low mobile engagement: slow first screen, pop-ups or a mismatch with the advert or search.
• Similar engagement, low conversion: the action is hard to find or hard to complete.
• Low mobile share of traffic: check rankings and adverts by device.
• Mobile converting close to desktop: the mobile site is doing its job.

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How do you find the page that is losing people?

Break the comparison down by landing page. Open the Landing page report under Engagement, add the mobile and desktop comparison, and sort by sessions. For each of your top five pages, compare the key event rate by device. The page with the widest gap and the most traffic is your first fix.

Then open that page on a phone and do what a visitor would. The numbers tell you where. Only using the page tells you why.

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Is the data telling the truth?

Only if the right things are tracked. If form submissions are recorded as key events but phone calls and WhatsApp taps are not, mobile is undercounted, because phone visitors are the ones who call and message. Set up key events for every route to an enquiry before trusting the comparison.

Two other gaps apply. Analytics cookies need consent in the UK, so visitors who decline are missing, and they may decline at different rates on different devices. And people who research on a phone and enquire later on a laptop are credited to desktop. Both make mobile look weaker than it is.

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What can GA4 not tell you?

GA4 shows what happened, not why. It can tell you that 70% of mobile visitors left the quote page without submitting. It cannot tell you that the form zoomed in, the keyboard hid the button and the error message was off screen. For that you need a real phone or a session recording tool.

It is also weak for small numbers. With 20 enquiries a month, a swing of three or four changes the conversion rate sharply. Use 90-day ranges, look for consistent patterns across pages, and avoid reading too much into one week.

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What does this look like in practice?

A pattern we see when owners open the device report for the first time: mobile has about two-thirds of the sessions and under a third of the recorded enquiries. The first reaction is that mobile visitors are less serious. Then it emerges that only form submissions are tracked, and the phone number is not a tap-to-call link.

The report was describing two faults: calls from mobile were invisible, and calling from mobile was harder than it should be. Fixing tracking and the link changes both the numbers and the reality. Global Bridge Labs (GBL) sets up call and WhatsApp tracking before drawing any conclusion from a device comparison.

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Monthly device review

• Open Tech details and select device category for the last 90 days.
• Note share of sessions and key event rate for mobile and desktop.
• Check that calls, WhatsApp taps and forms are all key events.
• Compare the top five landing pages by device.
• Open the worst page on a phone and attempt the main action.
• Record the figures so you can see the trend next month.

Next step

Open the device report today and write down two numbers: mobile's share of sessions and mobile's share of enquiries. The distance between them is the size of your opportunity.