E-Commerce Conversion Optimization: 10 UX Fixes That Turn More Browsers into Buyers

A few years ago, a Shopify store owner came to us spending $8,000 a month on ads. Good traffic. Terrible conversions stuck at 1.2%. He'd tried new photos, a better homepage, a discount popup. Nothing moved the number.

The real problem was hiding in the checkout. Fourteen form fields where six would do. No guest checkout option. Shipping cost appeared only at the final step — right when someone was about to pay.

Three design changes later, his conversion rate hit 3.8%. Same traffic, products and ad spend. Just a better experience. That's what this guide is about. Not redesigns and trends. Finding where your shoppers hit invisible walls and quietly removing them.

We'll walk through every stage of your store: homepage, product pages, cart, checkout, mobile, search, and what happens after someone places an order. These are the same frameworks we use at Orbix Studio when working with e-commerce brands who want more revenue from the visitors they already have.

Understanding What is E-Commerce Conversion Optimization?

Conversion optimization in e-commerce UX goes far beyond making "buy now" buttons bigger. It's about removing friction at every stage of the customer journey, building trust, smoothing interactions, and creating seamless experiences that make purchasing feel effortless and confident.

The e-commerce conversion funnel typically includes homepage/landing page, category pages, product pages, shopping cart, and checkout each stage presenting opportunities to lose potential revenue. Poor product filtering, confusing navigation, or abandoned carts are abandoned, representing massive lost revenue that strategic UX improvements can recover.

What's a Good Conversion Rate for Your Store?

This is one of the most common questions we hear from e-commerce founders, and the honest answer is: there's no single number that works for everyone. A 2% conversion rate might be excellent for a high-end furniture store and terrible for a fashion accessories shop.

The most important thing here is not to benchmark yourself against a generic '2-3% average' and call it a day. Compare yourself against your own industry, your own traffic sources, and your own product price points.

A $15 phone case and a $1,500 sofa will never have the same conversion rate and they shouldn't. What matters is whether your rate is improving over time and whether it's competitive within your category.

Here's a realistic breakdown of average conversion rates by industry, based on data from Shopify, Statista, and IRP Commerce:

How to Actually Approach E-Commerce Conversion Optimization?

Before we get into specific UX fixes, it helps to understand the process — because randomly tweaking things on your store without a system is how most optimization efforts fizzle out.

We've worked with dozens of e-commerce businesses, and the stores that consistently improve their conversion rates all follow a similar pattern. Here's the process we use:

Step 1. Audit Where You're Losing People Right NowF

You can't fix what you haven't found. The first step is always to look at your data and understand which pages have the highest exit rates and where shoppers drop off in the checkout flow.

Pull up Google Analytics (or whatever analytics tool you use) and look at your funnel. If 60% of people are leaving your product pages without adding anything to cart, that's where you start. If most of them add to cart but abandon at checkout, that's a different problem with a different fix.

Heatmap tools like Microsoft Clarity (it's free) or Hotjar are incredibly useful here they show you exactly where people click, how far they scroll, and what they're ignoring on your pages. Even 20 minutes of watching session recordings will show you things you never would have guessed.

Step 2. Understand Why Talk to Your Shoppers

Data tells you where people leave. It doesn't always tell you why. That's where a small amount of qualitative research goes a long way.

Exit surveys (a simple 'What stopped you from buying today?' popup when someone's about to leave) can give you insight that no analytics dashboard will show. You can also look through your support tickets and customer reviews complaints about confusing navigation, unexpected shipping costs, or not being able to find size guides are all direct signals of conversion problems.

You don't need a big research budget for this. Even 10 survey responses can point you toward the one change that makes the biggest difference.

Step 3. Fix the Biggest Friction Points First

Now comes the actual UX work and the rest of this guide covers exactly what to fix and how. But the key principle is this: start with the parts of your funnel where the most people are dropping off.

A 5% improvement in your checkout completion rate is worth more than a 20% improvement on a page that only 10% of visitors see. Work from the bottom of the funnel upward. Fix checkout first, then cart, then product pages, then navigation.

Step 4. Test Before You Declare Victory

Whenever you make a significant design change, run an A/B test if you have enough traffic to get meaningful results. This means showing 50% of your visitors the original version and 50% the new version, and measuring which one actually converts better.

We've seen 'obvious' fixes that made things worse. We've also seen tiny, almost invisible changes like moving a security badge two inches on a checkout page that meaningfully lifted revenue. You genuinely can't know until you test.

A reliable A/B test needs at least 100 conversions per variation before you can trust the results. Running a test for just a few days and calling a winner early is one of the most common CRO mistakes.

Step 5. Measure, Learn, and Repeat

Conversion optimization isn't a one-time project. The stores that hit 8% or 10% conversion rates didn't get there in a month they ran dozens of tests, learned from the results, and kept iterating.

Set a regular rhythm maybe once a month where you review your key metrics, pick one or two new things to test, and document what you've learned. Over time, these incremental wins compound into a meaningfully better-performing store.

Critical E-Commerce UX Elements That Drive Conversions

1. Homepage and Navigation: The Foundation

Your homepage sets expectations and guides discovery. Effective e-commerce UX begins with intuitive navigation that helps customers find products quickly.

Navigation best practices for conversion optimization:

• Implement mega menus showing category hierarchies at a glance
• Add level 1 search with autocomplete, spelling correction, and visual previews
• Display product categories and filtering options prominently
• Use breadcrumbs for easy back-tracking without browser back button
• Ensure all navigation is functional on screen bottom placement
• Include persistent cart icon showing item count

Homepage conversion tactics:

• Feature hero sections with clear value propositions and strong CTAs
• Showcase social proof (customer reviews, trust badges, press mentions)
• Display bestsellers and new arrivals with compelling imagery
• Use a clear value bar detailing offers and free shipping
• Optimize for Core Web Vitals (page load under 3 seconds)

2. Product Page Optimization: Where Decisions Happen

Product pages are where conversion optimization truly matters. These pages must inform, persuade, and overcome objections simultaneously.

High-converting product page elements:

Visual presentation requires multiple high-quality images from different angles, zoom functionality for detail inspection, 360-degree views or videos demonstrating products in use, and lifestyle images showing products in context. Video content on product pages increases conversion rates by 80%.

Product information must include clear, scannable descriptions highlighting benefits over features, detailed specifications in easy-to-read tables, size guides and comparison charts, and transparent information about materials, dimensions, and care instructions.

Trust and social proof elements include detailed customer reviews with product ratings, ratings displayed prominently, number of reviews and purchases, verified buyer badges, and expert recommendations or certifications.

Conversion triggers encompass clear pricing with any discounts shown, prominent add-to-cart button in the first fold, clear presentation of stock availability, expected delivery timeframes and shipping costs upfront, and easy access to customer service (live chat, contact info).

Psychological optimization tactics:

• Use urgency and scarcity recommendations to increase average order value
• Display recently viewed items for easy return
• Show a time-bound purchase or stock limits to create urgency
• Offer "free shipping over" to encourage larger purchases
• Provide "Add to Wishlist" for products customers aren't ready to buy

3. Shopping Cart: Maintaining Momentum

Cart abandonment is the biggest challenge in e-commerce conversion rate optimization. Strategic UX design keeps customers moving toward checkout.

Cart optimization strategies:

• Show clear product thumbnails, names, prices, and quantities
• Allow inline quantity editing without page reloads
• Display running total with estimated shipping and taxes
• Prominently show free shipping thresholds and progress
• Include "Continue Shopping" option without losing cart
• Add security badges near checkout button
• Implement persistent cart across devices (logged-in users)
• Show estimated delivery dates
• Offer product recommendations to increase order value

Cart abandonment reduction tactics:

• Send abandoned cart emails within 1 hour (recover $10\%$-$30\%$ of lost sales)
• Offer live chat assistance on cart page
• Display return policy and guarantees
• Show multiple payment options accepted
• Enable guest checkout without forced registration
• Add exit-intent popups with discount offers

4. Checkout Optimization: The Critical Final Step

Checkout optimization is where e-commerce conversion optimization has the highest impact. Complex or lengthy checkout processes cause $28\%$ of cart abandonments.

Streamlined checkout best practices:

Minimize steps by combining billing and shipping on one screen, showing progress indicators (Step 2 of 3), auto-filling information when possible, and saving customer data for returning users.

Reduce form friction through smart form design including auto-detection of card type from numbers, address autocomplete via APIs, clear error messages with guidance, inline validation showing errors immediately, optional fields clearly marked, and mobile-optimized keyboard types.

Build trust throughout checkout with SSL certificates and security badges visible, accepted payment logos displayed, clear return and refund policies linked, real-time customer support available, order summary always visible, and no surprise costs at final step.

Payment flexibility includes multiple payment options (credit cards, PayPal, Apple Pay, Google Pay, buy-now-pay-later services), one-click checkout for returning customers, and clear pricing breakdown showing subtotal, shipping, taxes separately.

Mobile checkout optimization:

• Large touch targets for all buttons and form fields
• Minimal typing required (use dropdowns, autofill)
• Thumb-friendly button placement
• Progress saved automatically
• Digital wallet integration (Apple Pay, Google Pay)

5. Mobile E-Commerce UX: The Priority Platform

Mobile commerce represents over 70% of e-commerce traffic and continues growing. Mobile e-commerce UX requires specialized optimization.

Mobile-first conversion tactics:

• Simplified navigation with bottom-positioned menus
• Large product images optimized for small screens
• Thumb-friendly add-to-cart buttons
• Streamlined checkout (ideally single-page)
• Sticky add-to-cart and checkout buttons
• Touch-optimized image galleries with swipe
• One-tap payment options (Apple Pay, Google Pay)
• Click-to-call customer service
• Progressive web app features for app-like experience

6. Search and Filter Functionality

Effective search drives 2-3x higher conversion rates than site navigation. Search optimization is critical for e-commerce conversion optimization.

Search features that convert:

• Autocomplete suggestions with product images
• Typo tolerance and synonym recognition
• Voice search capability for mobile users
• Search result page design matching product grid
• "No results" pages offering alternatives

Advanced filtering for product discovery:

• Multiple filter types (price, size, color, brand, rating)
• Visual filter options (color swatches, not dropdowns)
• Active filter display with easy removal
• Filter result counts showing available options
• Sort options (price, popularity, newest, rating)
• Save filter preferences for returning users

7. Trust and Credibility Signals

Online shoppers need reassurance before purchasing. Trust elements significantly impact e-commerce conversion rates.

Essential trust indicators:

• SSL certificate with visible padlock icon
• Trust badges (Norton, McAfee, BBB)
• Payment security logos
• Customer reviews and ratings (display 4.0+ prominently)
• Money-back guarantees
• Free return policies
• Contact information easily accessible
• About page with company story
• Professional photography and design
• Social media presence and engagement

Strategic trust placement:

• Homepage: Company credentials, awards, customer count
• Product pages: Reviews, ratings, guarantees
• Cart: Security badges, return policy
• Checkout: SSL indicators, payment logos, support contact

8. Personalization and Recommendations

Personalized e-commerce UX increases conversion rates by 20-30% by showing relevant products and content.

Effective personalization strategies:

• Product recommendations based on browsing history
• "Customers who bought this also bought" suggestions
• Recently viewed items section
• Personalized homepage content for returning visitors
• Abandoned cart reminders via email
• Dynamic pricing or offers based on customer segment
• Location-based shipping estimates and store suggestions

9. Performance and Speed Optimization

Every second of load time costs conversions. One-second delay reduces conversion rates by 7%.

Speed optimization priorities:

• Optimize images (WebP format, lazy loading)
• Implement CDN for faster global delivery
• Minimize JavaScript and CSS
• Use browser caching effectively
• Enable compression (Gzip/Brotli)
• Optimize for Core Web Vitals (LCP, FID, CLS)
• Implement progressive loading (show content incrementally)

Target metrics:

• First Contentful Paint: under 1.8 seconds
• Time to Interactive: under 3.5 seconds
• Page load complete: under 5 seconds

10. Post-Purchase Experience

Conversion optimization doesn't end at checkout. Post-purchase UX drives repeat business and lifetime value.

Optimized post-purchase elements:

• Clear confirmation page with order details
• Immediate confirmation email
• Order tracking with real-time updates
• Proactive shipping notifications
• Easy returns process
• Follow-up emails requesting reviews
• Loyalty program enrollment
• Personalized product recommendations
• Exclusive offers for returning customers

A/B Testing for Continuous Optimization

E-commerce conversion optimization requires continuous testing and refinement. A/B testing identifies what actually improves conversions versus assumptions.

High-impact elements to test:

• CTA button colors, sizes, and copy
• Product page layouts and image sizes
• Checkout flow variations (one-page vs. multi-step)
• Shipping cost presentation
• Trust badge placement and types
• Recommendation algorithm effectiveness
• Email subject lines and timing
• Discount presentation methods

Testing best practices:

• Test one variable at a time for clear results
• Run tests long enough for statistical significance (minimum 2 weeks)
• Consider seasonality and external factors
• Test across devices and browsers
• Measure beyond conversion rate (AOV, revenue per visitor)

The Tools You Actually Need to Track and improve Your E-Commerce Conversion Rate

You don't need a $2,000/month tech stack to do conversion optimization well. But you do need the right tools for the right jobs because trying to guess what's wrong with your store without data is like trying to diagnose a car problem by listening to it from across the street.

Here's a practical breakdown of what each category of tool does and which ones are worth starting with:

1. Analytics Understanding What's Happening

This is your foundation. If you don't have solid analytics set up, you're flying blind.

• Google Analytics 4 (GA4)
• Shopify Analytics or WooCommerce Reports

2. Heatmaps & Session Recordings Understanding Why

These tools let you literally watch how visitors use your site. It sounds simple, but nothing will teach you more about your conversion problems faster.

• Microsoft Clarity
• Hotjar
• Crazy Egg

3. A/B Testing Finding What Actually Works

Once you have a hypothesis about what's hurting conversions, these tools let you test the fix before you fully commit to it.

• Google Optimize
• VWO (Visual Website Optimizer)
• Optimizely
• Shoplift or Intelligems

4. Site Speed Testing Because Slow = Fewer Sales

Every second your pages take to load costs you conversions. Here's how to measure and diagnose it.

• Google PageSpeed Insights
• WebPageTest.org
• GTmetrix

5. User Research Hearing It Directly

Sometimes the most valuable conversion insight comes from just asking your customers a direct question.

• Typeform or Google Forms
• Hotjar Surveys

Measuring E-Commerce UX Success

Track these metrics to evaluate your conversion optimization efforts:

Conversion metrics:

• Overall conversion rate (target: 3-5%+)
• Add-to-cart rate (target: 10-15%)
• Cart abandonment rate (target: under 65%)
• Checkout abandonment rate (target: under 20%)

Revenue metrics:

• Average order value (AOV)
• Revenue per visitor (RPV)
• Customer lifetime value (CLV)
• Return on ad spend (ROAS)

Engagement metrics:

• Pages per session (target: 5+)
• Session duration (target: 3+ minutes)
• Bounce rate (target: under 50%)
• Product page views per session

Common E-Commerce UX Mistakes That Are Silently Killing Your Conversions

Most conversion problems aren't dramatic. You won't see a big red error message or a broken page. They're quiet — a form field that's slightly confusing, a shipping cost that shows up too late, a checkout that asks for one or two things too many. These small things add up to thousands of abandoned purchases every year.

Here are the mistakes we see most often when auditing e-commerce stores, and what to do about each one:

1. Making People Create an Account Before They Can Buy

This is the single most studied and confirmed conversion killer in e-commerce. Forcing account registration before checkout consistently causes around 23–25% of shoppers to abandon their carts, according to multiple UX research studies.

It happens because the store wants to capture customer data. But the shopper just wants to buy the thing. When you put a barrier between them and their purchase, a significant chunk of them will simply leave.

Fix: Add a prominent 'Continue as Guest' option on the checkout page. Let people complete their purchase first, then offer to save their details for next time with a single click. You get the data either way but you don't lose the sale to get it.

2. Hiding Shipping Costs Until the Last Step

Surprise costs at checkout are the leading cause of cart abandonment globally. Shoppers add items, go through the checkout process, and then discover at the final screen that shipping costs $12.99  and they feel tricked. Even if it's not intentional, it feels like a bait-and-switch.

Fix: Show estimated shipping costs early ideally on the product page or at least at the beginning of checkout. If you offer free shipping over a certain threshold, make that visible throughout the shopping experience, not just in the fine print.

3. A Checkout Process That Has Too Many Steps

Research from Baymard Institute shows the average e-commerce checkout has 11.8 form fields, when most purchases only require about 6. Every extra field is a small moment of friction and they compound. The more steps, the more chances for someone to get interrupted, second-guess themselves, or just give up.

Fix: Combine your billing and shipping information onto one screen if possible. Remove any fields that aren't strictly necessary to complete the order. If you have fields you want but don't need like a phone number for marketing, make them clearly optional.

4. A Mobile Experience That Feels Like an Afterthought

More than 70% of e-commerce traffic now comes from mobile phones, but most stores still convert at half the rate on mobile compared to desktop. That gap isn't because people are less willing to buy on their phones it's because the experience is genuinely harder.

Tiny buttons, text that requires zooming, forms that don't auto-fill, and checkout pages where the keyboard covers the input field these are all design problems that could be fixed but often get ignored because the team reviews the site on a desktop.

Fix: Do your own QA on the most popular phone screen sizes iPhone and mid-range Android. Go through the entire purchase flow yourself on mobile. You'll find the problems within 10 minutes.

5. Product Pages That Don't Answer the Questions Shoppers Are Actually Asking

When a shopper can't get the information they need from your product page dimensions, materials, how it fits, what it looks like in real life they don't magically buy anyway. They leave and look for a product that does tell them.

Common culprits: images that are too small to see details, descriptions that focus on features instead of what those features mean for the buyer, missing size guides, and no customer reviews to validate the purchase.

Fix: Think about what question a first-time buyer would have for each product and answer all of them on the page. 'Will this fit in my space?' 'What does it feel like?' 'Is it worth the price?' Product pages that preemptively answer objections convert much better than those that just list specs.

6. Slow Pages Especially on Mobile

A one-second delay in page load time reduces conversion rates by around 7%, according to research cited by Google. For mobile users, slow loading is even more punishing because mobile networks are less reliable and users are typically less patient when browsing on a phone.

Large uncompressed images are the most common culprit on Shopify and WooCommerce stores. A single product hero image served at full camera resolution can be 4–6MB that's five to ten times what it should be.

Fix: Compress and resize every product image before uploading. Use WebP format instead of JPG or PNG where possible. Run your key pages through Google PageSpeed Insights and work through the specific recommendations it gives you.

7. No Trust Signals or Trust Signals in the Wrong Places

When someone buys from your store for the first time, they're trusting you with their credit card details and their money. That's a significant act of trust, especially for a brand they've never heard of before.

Stores often have trust elements security badges, money-back guarantees, return policies but they're buried in the footer or only mentioned on the About page. By the time someone reaches checkout, they want to see them right there, in the checkout itself.

Fix: Put your most reassuring trust signals close to the 'Place Order' button: your return policy, a security badge, and a simple statement of what happens if something goes wrong. Visible trust at the moment of decision matters far more than trust buried elsewhere on the site.

8. A Search Function That Doesn't Really Work

Shoppers who use your site search are often your highest-intent visitors they know what they want and they're looking for it specifically. A search function that returns irrelevant results, can't handle typos, or shows 'no results' for products that actually exist will lose that sale almost instantly.

Fix: At minimum, make sure your search can handle singular/plural variations and common misspellings of your product names. If your store is large enough to justify it, a dedicated search tool like Searchanise, Searchpie, or Boost Commerce will significantly improve search-driven conversions.

9. No Return Policy or a Policy That's Hard to Find

A generous, clearly visible return policy actively increases conversions. It sounds counterintuitive 'but won't more people return things?' but the research consistently shows that easy returns increase purchases more than they increase returns, because they reduce the risk shoppers feel.

Fix: Make your return policy visible on product pages and in the checkout, not just in your footer. If you offer free returns, say so clearly. A shopper on the fence about a $90 purchase will often commit if they know they can return it without hassle.

10. Coupon Fields That Send People Hunting for Discounts

This one surprises a lot of store owners. When shoppers see an open coupon code field at checkout, a significant percentage of them will stop, open a new tab, and search the internet for a discount code. Some find one. Many don't. But many of the ones who don't find a code feel like they're overpaying and abandon the cart.

Fix: Collapse the coupon field behind a 'Have a code?' link rather than showing an open input field by default. The option is still there for people who have a code they just need to click to access it. You'll see fewer people leaving mid-checkout to hunt for discounts.

Conclusion

E-commerce conversion optimization through strategic UX design delivers exponential returns. Small improvements compound optimizing product pages, streamlining checkout, building trust, and personalizing experiences can double or triple conversion rates.

The most successful online stores obsess over every detail of the customer journey, continuously test improvements, remove friction points, and prioritize user needs above internal preferences. In e-commerce, superior user experience is your sustainable competitive advantage.

At Orbix Studio, we specialize in e-commerce UX design that drives measurable conversion increases. Our data-driven approach combines user research, strategic design, and rigorous testing to optimize every touchpoint in your customer journey—from first click to loyal repeat customer.

Frequently Asked Questions

What is a good conversion rate for an e-commerce store?

A good conversion rate varies by industry, but most e-commerce stores average between 1% and 3%. Fashion and beauty stores tend to sit at 1.5–4%, while electronics and furniture stores typically see 0.5–1.5% because the purchases are bigger and people think longer before buying. Instead of comparing yourself to an industry average, the more useful question is: 'Is my rate improving?' Even small consistent gains going from 1.8% to 2.3% can mean thousands of dollars in extra revenue without spending more on traffic.

Why is my conversion rate low even though I'm getting traffic?

Traffic and conversions are two completely different problems. Low conversions with decent traffic almost always point to a friction issue on the site itself — not an audience problem. The most common culprits are: a checkout that's too long or asks for too much information, shipping costs that show up as a surprise at the end, product pages that don't answer shoppers' key questions, or a site that's slow or hard to use on mobile. A heatmap tool like Microsoft Clarity (free) will show you exactly where people are dropping off. Most of the time, one or two specific friction points are responsible for the majority of lost sales.

How do I reduce cart abandonment on my e-commerce site?

Cart abandonment averages around 70% across e-commerce meaning 7 out of 10 people who add something to their cart don't complete the purchase. The most effective ways to reduce it are: show all costs including shipping early in the process, add a guest checkout option so people don't have to create an account, simplify the checkout form to remove unnecessary fields, and add visible trust signals like your return policy and a security badge close to the payment section. If you have enough traffic, an abandoned cart email sent within the first hour can recover 10–20% of those lost sales.

What's the difference between UX design and conversion rate optimization?

UX design is about creating an experience that's genuinely easy and pleasant to use. Conversion rate optimization is about improving the percentage of visitors who take a specific action usually buying something. In e-commerce, the two are deeply connected. Good UX design is the foundation of good CRO. You can't run A/B tests on a checkout form and expect big wins if the form is fundamentally broken you need solid design first, then optimization on top of it. Think of UX design as building the engine and CRO as tuning it.

How long does it take to see results from conversion optimization?

It depends on how much traffic your store gets. Quick technical fixes like adding guest checkout or showing shipping costs earlier can show results within days if your traffic is high enough to measure. A/B tests typically need 2–4 weeks to reach statistical significance, sometimes longer for lower-traffic stores. The honest timeline for meaningful CRO work is 60–90 days from first audit to measurable improvement, assuming you're running tests systematically. Stores with under 10,000 monthly visitors may find it difficult to get statistically reliable test results quickly, in which case focusing on fixing obvious friction points (rather than testing small variations) is the better approach.

What tools do I need to start improving my e-commerce conversion rate?

You don't need an expensive tech stack to start. For most stores, three free tools cover the basics: Google Analytics 4 for tracking where people drop off in your funnel, Microsoft Clarity for heatmaps and session recordings to understand why, and your own platform's built-in analytics (Shopify, WooCommerce, etc.) for product and order data. Once you've identified your main conversion problems from the data, you can look at A/B testing tools like VWO or Optimizely to test your proposed fixes before rolling them out completely.

Does page speed really affect my conversion rate?

Yes, meaningfully. Google's own research shows that as page load time increases from 1 second to 5 seconds, the probability of a visitor bouncing increases by 90%. For e-commerce specifically, a one-second delay in load time is associated with roughly a 7% reduction in conversions. Mobile users are especially sensitive to slow loading because they're often on less reliable connections. Run your key pages through Google PageSpeed Insights and focus on image compression and lazy loading first those two things alone account for the majority of speed problems on most e-commerce sites.

Should I use a one-page or multi-step checkout for better conversions?

There's no universal answer it genuinely depends on your audience and the complexity of your checkout. One-page checkouts work well when the form is simple and the customer data needed is minimal. Multi-step checkouts with clear progress indicators can feel less overwhelming when there's more information to collect. The best approach is to test both with your actual customers rather than assuming one is better. What we consistently see is that the number of fields matters more than the number of pages a three-step checkout with 6 total fields will outperform a one-page checkout with 14 fields every time.

Can improving UX on my store really double my sales without more traffic?

It's not guaranteed to double your sales, but meaningful CRO work consistently delivers significant revenue gains from existing traffic. Going from a 1.5% conversion rate to a 3% rate which is achievable for most stores with proper optimization literally doubles the revenue you get from every visitor. Because you're not spending more on ads or SEO to get that result, the return on investment for UX and conversion work tends to be extremely high. The reason more stores don't do it is that it requires careful analysis and willingness to test, not just 'change things and hope.