Mobile Checkout Optimization: Why 70% of Your Mobile Visitors Don't Buy

Your analytics tell a clear story: mobile is 68% of your traffic and 0.9% of your conversions. Desktop is 32% of traffic and 2.6% of conversions.

You’re leaving money on the table every day.

The desktop/mobile conversion gap is one of the most consistent patterns in ecommerce data. Nielsen Norman Group research consistently shows mobile users abandoning at far higher rates than desktop - not because they don’t want to buy, but because the experience makes buying harder than it should be.

This is a solvable problem. Not with a complete rebuild. With specific, targeted fixes to the friction points that matter most.

Why the Gap Exists

Mobile users aren’t less motivated. They have different constraints.

They’re often one-handed. Screen space is limited. Keyboards are small and autocorrect breaks things. Network connections vary. And critically - the payment step feels riskier on a small screen with a potentially insecure connection than at a desktop at home.

Baymard Institute’s mobile UX research (over 50,000 hours of testing across major retailers) identifies several patterns that consistently drive mobile abandonment:

Form fields not optimized for mobile input (wrong keyboard type, no autocomplete)
Tap targets too small for accurate finger input
Critical information hidden below the fold
Checkout flow requiring too many steps
Trust signals absent at the payment step

None of these are hard to fix. Most don’t require a theme rebuild.

Fix 1: Optimize Every Form Field for Mobile Input

The single biggest mobile checkout problem. Most stores have fields configured for desktop and never tested on mobile.

Specific checks:

Email field: Should trigger email keyboard (with @ symbol prominent). Use type="email" in your form HTML.

Phone field: Should trigger numeric keyboard. Use type="tel".

Credit card number: Should trigger numeric keyboard on mobile. Use inputmode="numeric" or type="tel".

Expiry date: Should be numeric. Don’t use a date picker that opens a calendar widget - a calendar is the wrong UI for MM/YY input.

Postal/ZIP code: Should trigger numeric keyboard in US/NL/DE markets. Add autocomplete="postal-code" for browser autofill.

Address fields: Add autocomplete attributes for every field (given-name, family-name, address-line1, address-line2, locality, region, postal-code, country). This enables browser and password manager autofill, which can cut form completion time in half on mobile.

This alone - just fixing form input types and autocomplete attributes - consistently reduces mobile checkout abandonment in the 8-15% range in controlled tests.

Fix 2: Enable Digital Wallets

The fastest way to increase mobile checkout completion. Dramatically.

When a mobile user can tap “Pay with Apple Pay” or “Pay with Google Pay” and complete the purchase with their fingerprint, you’ve eliminated:

All card entry friction
Billing address entry friction
Shipping address entry friction (if saved)
Trust anxiety (familiar payment interface from a trusted provider)

Baymard data shows Apple Pay can increase mobile conversion rates by 5-15% on sites that previously required manual card entry for a large portion of mobile traffic.

On Shopify: enable Shop Pay, Apple Pay, and Google Pay in your Payments settings. Show these options early - ideally above the fold on the cart page and at the top of checkout. Don’t bury them below the card entry form.

Fix 3: Show Costs Before Checkout

The most common reason for mobile checkout abandonment: surprise costs.

48% of cart abandoners cite unexpected shipping or tax costs as their reason (Baymard, 2024). On mobile, this is worse because users have already committed enough cognitive effort to get to checkout. The surprise cost at the end feels like being tricked.

Fix: Show shipping cost estimation on the cart page. If you can auto-detect country from browser locale and estimate cost before checkout even starts, do it. If not, at minimum show the shipping cost on the first checkout step, not the last.

For stores with free shipping thresholds: show the threshold progress clearly in the cart. “Add €12 more for free shipping” is a higher-impact message than it looks.

Fix 4: Sticky Add-to-Cart and Checkout Buttons

On mobile product pages and cart pages, the primary action button scrolls out of view as users read content. This forces them to scroll back up - creating friction and decision fatigue.

Sticky CTA buttons on mobile are a standard pattern for a reason. Nielsen Norman research consistently shows that visible, accessible CTAs increase click-through rates.

Implementation:

Sticky “Add to Cart” at bottom of product page on mobile (disappears when the button is naturally visible)
Sticky “Checkout” or “Place Order” button on cart and checkout summary screens
Ensure the sticky button has sufficient padding (minimum 44px tap target height per Apple’s HIG guidelines)

The button itself matters too. On mobile, low-contrast buttons fail. A gray “Checkout” button on a light background doesn’t read as primary action. Use your highest-contrast color combination for the primary CTA.

Fix 5: Simplify the Checkout Flow

Desktop checkout is already too long for most stores. On mobile, every extra step is amplified.

The Baymard benchmark: the ideal checkout has 12-14 form fields for a guest checkout. The average ecommerce checkout has 23. Each extra field is a chance to abandon.

Specific reductions that help mobile disproportionately:

Remove Address Line 2 from the main form. Add a ”+” button to show it only if needed. Most orders don’t need it. Having it as a prominent empty field creates uncertainty (“Am I supposed to fill this in?”).

Don’t ask for phone number if you don’t use it. If you’re not sending SMS updates, remove it. It’s friction with no value.

Combine first and last name into one field. Fewer taps.

Auto-detect city and state from postal code. This works in most markets and eliminates 2-3 fields entirely for the majority of users.

Guest checkout by default. Account creation should be an option after purchase, not a requirement before it. 26% of abandoners specifically cite forced registration as their reason for leaving.

For the detailed checklist of checkout changes by impact level, the checkout optimization guide covers each friction point with implementation specifics.

Fix 6: Mobile-Specific Trust Signals

Desktop users have more screen real estate for trust signals. They see the security badges, reviews, and return policy naturally as they scroll. Mobile users often don’t.

On mobile checkout specifically:

Show SSL/security indicator near the payment form
Add a brief return policy summary near the “Place Order” button (not just in the footer)
If you have reviews or a “10,000+ customers” badge, show it on mobile too - not just on desktop

Trust anxiety is higher on mobile because the browser URL bar is often hidden, the interface is cramped, and users feel more exposed entering payment details on a small screen.

Measure Before and After

Before making any changes, set up proper mobile tracking:

In Shopify Analytics or GA4, segment all key metrics by device type:

Add-to-cart rate (by device)
Cart-to-checkout rate (by device)
Checkout completion rate (by device)
Conversion rate (by device)

Note the starting numbers. After implementing changes, track the same metrics. Don’t combine mobile and desktop data - they need to move independently.

The biggest mistake: implementing all changes at once and not knowing which one drove the improvement. Prioritize by expected impact and implement in order if you want to learn.

What to Prioritize First

If you’re overwhelmed by the list, start here in order:

Enable Apple Pay and Google Pay - immediate impact, zero design work
Fix form field input types and autocomplete - high impact, low effort
Show shipping cost on cart page - reduces surprise at checkout
Add sticky checkout button on mobile - reduces scroll friction
Remove unnecessary form fields - requires testing but high payoff

Each of these is addressable in a day or less for a technical Shopify store owner. None require a theme rebuild.

For the broader context on what cart abandonment actually means and how to interpret your data, cart abandonment fixes covers the full picture - mobile is the biggest lever for most stores, but it’s not the only one. For the full mobile UX picture beyond checkout, see The Ultimate Guide to UX Design for Mobile.

And for the research process that helps you find the specific problems in your store rather than applying generic fixes, the conversion diagnostic framework is the place to start.

Philip Wallage is a conversion-focused UX designer who has audited 100+ ecommerce stores. He runs BTNG.studio, a design service for ecommerce brands in Europe. If you want to know exactly what’s holding your mobile checkout back, book a UX audit.