Why Mobile Converts Lower (Normally)
Mobile converts 10-20% lower than desktop. That's expected. Smaller screen. Tap targets are tighter. Less real estate to show trust signals. Users browse on their phone while doing something else. Distracted.
But 10-20% lower isn't the same as 30%+ lower. A gap larger than that means something's actively broken, not just harder.
Your desktop CR is 3.2%. Your mobile CR is 2.2%. That's a 31% gap. Your store is leaving 30-40% of revenue on the table because your mobile experience is fighting you.
The Common Mobile Killers
Image load speed. Mobile networks are slower. A 5MB hero image that loads instantly on fiber takes 3 seconds on LTE. Users leave.
Sticky ATC button missing. On desktop, the buy box is visible. On mobile, visitors scroll past it and can't find it. They have to scroll back up.
Form friction on checkout. Desktop checkout is fast. Mobile keyboard keeps popping up. Forms require more taps. Fewer people finish.
Button tap targets under 44px. Fingers are bigger than mouse cursors. A 30px button is too small. Users miss it. They click nearby instead. Nothing happens. They bounce.
Text too small. Default text smaller than 14px on mobile requires pinch-to-zoom. Users won't pinch. They bounce instead.
Popup aggression. A popups the second they land annoys everyone. On mobile, it covers the screen. They leave immediately.
Hero section takes the whole screen. Desktop users see hero + fold content. Mobile users see only hero. They need to scroll just to find products. Extra friction.
Most of these are fixable in hours, not days. Speed up images. Add a sticky ATC. Bump button size to 44px square. Increase text to 16px base. Remove unnecessary popups. Hide hero on mobile or reduce height.
How to Diagnose the Gap
Pull your GA4 device report. Filter by device and look at CR.
Desktop: 3.2%. Tablet: 2.8%. Mobile: 2.1%. Your mobile gap is 34%. That's a red flag.
Now watch replays. Load your store on an actual iPhone and Android phone. Don't emulate. Use real devices. Load speed matters. Touch responsiveness matters. Emulation lies.
Watch 10 mobile replays and 10 desktop replays from the same segment (traffic source, date range). Document the differences. Where do mobile visitors struggle that desktop visitors don't?
The Quick-Win Checklist
Run through these in 30 minutes. Most gaps close immediately after fixing one of these.
Check image sizes. Your hero image shouldn't exceed 200KB. Use a tool like TinyPNG or ImageOptim. Compress.
Check button sizes. Every CTA button must be at least 44px square. No exceptions.
Check text legibility. Minimum 16px font size. 14px is unreadable without zooming.
Check sticky elements. Is the "Add to Cart" button sticky on mobile? Can users add to cart without scrolling back up?
Check form fields. How many fields in your checkout? Each field is friction. Can you reduce to 5 fields or fewer on mobile?
Check popup timing. Does a newsletter popup load on page entry? Move it to exit-intent or remove entirely on mobile.
Want me to audit your mobile?
I'll load your store on 3 real devices and map every friction point.
Why This Compounds
Mobile is 60-75% of most stores' traffic. If 70% of your traffic converts at 30% lower rate, your overall CR is being crushed.
A store with 2.5% overall CR might have desktop at 3.8% and mobile at 2.0%. Desktop is strong. Mobile is weak. But because mobile is 70% of traffic, it drags the average down.
Fix mobile. Move it from 2.0% to 2.8%. Your overall CR moves from 2.5% to 3.1%. That's not a small change. That's 24% revenue growth from one fix.