Partly because the visits aren't the same. Mobile gets discovery, social media traffic, and visits that last a few seconds.
Desktop more often gets people coming back to buy.
Usability matters, but it doesn't explain the whole gap. The phone absorbs discovery, the computer harvests the end of the journey, and your report gives the medal to the second.
The benchmark
The gap exists everywhere. In the 2026 Contentsquare benchmark, desktop conversion is 74% higher than mobile, even though mobile brings 69.9% of visits. Keep a ratio of around 1.7 in mind.
At a brand whose sales peak in winter, the authors measured mobile at 1.5 to 2.4% versus desktop at 2.7 to 9.5%, on 80 to 90% mobile traffic: a ratio of 2 to 4, well beyond the market.
The authors' read since then: if your ratio exceeds 2, the gap is no longer structural, it's on you. Your own gap shows up first when you compare mobile and desktop for the same traffic source.
The rule
Compare mobile to mobile. Your reference is last year's mobile rate, for the same source, not your desktop rate.
The steps
- Mobile conversion by source. Does the gap shrink when you isolate direct or email traffic?
- The drop-off point. Where do mobile visits stop: product page, cart, checkout?
- The real-world test. Go through your site on a real phone, on 4G, with one hand.
- The express payments. Check that they're there, because they save shoppers from typing.
- The line for leadership:
"We compare our mobile to our mobile from last year, for the same source. The ratio with desktop remains a market benchmark."
The trap
Concluding that "mobile doesn't convert" and cutting its budget. The authors' read, based on the journeys they observe: the same person discovers a brand on their phone during their commute and buys that evening on their computer.
If you measure each device separately, you credit the sale to the device that closes it and forget the one that introduced the brand.
A cart saved from one device to the next mostly keeps you from losing that sale.
