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Find where mobile falls behind desktop

You'll know whether mobile converts worse because of the catalog, the checkout form, or because customers buy later on another device, and what to fix first.

By Yodai · Published September 6, 2026 · Updated October 12, 2026

Imagine that half of this month's visits come from mobile, but almost every order is placed from a computer. The first thought that comes to mind is quick: "mobile just doesn't sell." The problem is that thought doesn't tell you what to fix, and fixing the wrong thing wastes time.

Maybe the problem is the catalog, which looks bad on a small screen and nobody makes it to the product or service page. Maybe it's the checkout form, where typing in card details with your thumb turns a lot of people away. Or maybe there's no real problem at all: some people browse on their phone in the morning on the couch and pay in the afternoon from their work computer, with nothing broken along the way. Each of these three cases gets fixed differently, so before you touch anything, you need to know which one is yours.

Compare conversion, not traffic

Break your site into stages you can count: arrives, views the catalog, starts checkout, completes the purchase. If your analytics let you split each stage by device, look at mobile and computer separately. Don't compare how many visits come from each one, that only tells you where people come from. Compare what percentage of each stage moves on to the next one, for each device. If your analytics only give you total visits by device, the test purchase from your own phone described below will give you a first clue.

An example with made-up numbers: at an auto parts store, out of every 100 visits from mobile, 40 open a product page, 16 start checkout, and 4 complete the purchase. From a computer, out of every 100 visits, 45 open a product page, 18 start checkout, and 9 complete the purchase. The catalog performs about the same on both devices: 40 versus 45. Starting checkout is about the same too: 4 out of 10 of those who open a product page, on both. The big difference is in the last step: of those who start checkout, on mobile only 1 in 4 finishes, and on computer, half do.

That bar shape, flat at first and then spiking at the end, is the signature of a checkout form that wasn't built for mobile. If instead the difference is already large from the first stage, the problem isn't checkout: it's that the catalog's photos, text, or buttons don't work well on a small screen, and people leave before getting anywhere.

Three places where it can break down

The first suspect is the catalog: photos that take too long to load on mobile data, buttons too small for a thumb, text that forces you to zoom in to read it. You'll spot it because the drop-off is already there as soon as someone opens the product page, before anyone even gets to checkout.

The second is the checkout form: too many fields, a keyboard that doesn't automatically switch to numbers when entering card details, a pay button that sits off-screen until you scroll. You'll spot it because up to that point mobile and desktop were tracking evenly, and the drop-off hits right at the last step, entering the payment info.

The third isn't a problem, it's a habit: some businesses have customers who browse on their phone in the morning and buy on their computer in the afternoon, especially for bigger purchases or ones that need some thought. You'll spot it because the gap between the two devices stays the same month after month, even though you haven't changed anything, and overall business keeps growing.

With this, you stop treating mobile as one single block and know exactly which stage falls behind desktop, and whether what needs fixing is the catalog, the checkout form, or nothing at all. Next week, you'll choose which change to make first out of everything you've found in this course.

You know where mobile falls short compared to desktop, and exactly which stage the gap opens up in. But now you have several stages bleeding customers at once and only one month ahead: the next lesson tells you which one to fix first, the one losing more people in raw numbers, not the one losing more in percentage.