Shopify Plus CRO: what Plus changes for conversion rate optimisation, and where to start

Shopify Plus CRO is conversion rate optimisation for stores on Shopify Plus. Most of the work is the same as on any Shopify plan, but Plus opens up parts of the store that other plans cannot touch, mainly the checkout, and most Plus brands have enough traffic to test changes properly. This guide covers what Plus changes, what it does not, how to test on Shopify today, and where to start. Platform details come from Shopify’s help centre, developer documentation and changelog, checked in October 2026.

What is different about CRO on Shopify Plus?

A product page, a collection page and a cart work the same way on Basic as on Plus, so the research and testing methods do not change. What changes is how far you can go once you find a problem. This table sets out the conversion levers that depend on your plan, from Shopify’s own documentation:

Two things stand out. First, A/B testing is no longer a Plus feature: Shopify’s native experiments run on Grow and above. Second, the checkout is where Plus is still different, and it is also the part of the funnel closest to revenue.

Checkout: where Plus makes the biggest difference

Shopify’s checkout already converts well before you change anything. Shopify reported in 2023, from a study by a global management consultancy, that its checkout converts up to 36% better than competing platforms, and that Shop Pay can lift conversion by up to 50% compared with guest checkout. Those are Shopify’s own figures, but they explain why CRO on a Plus checkout is rarely about rebuilding it. The job is to add what a customer needs to finish the order, and to remove anything that makes them hesitate.

On Plus, checkout UI extensions let you add content and fields to the information, shipping and payment steps. Typical uses include:

• Delivery promises, such as estimated delivery dates or a nominated day picker, shown next to the shipping methods.
• Reassurance at the payment step: returns policy, guarantees, review scores or security notes.
• Extra fields such as gift messages, delivery instructions, VAT numbers or purchase order numbers for B2B buyers.
• Upsells and add ons, such as protection, samples or a product that completes the order.
• Address and data checks that catch mistakes before the order is placed.

Every block you add is something the customer has to read. Treat each one as a test, not a feature, and add them one at a time so you can see what each does. Shopify’s Rollouts can now A/B test checkout configurations as well as themes, which makes this much easier than it used to be.

If you are still relying on checkout.liquid or Shopify Scripts, that work has to move. Shopify has retired checkout.liquid for the information, shipping and payment steps, and Scripts stopped running on 30 June 2026. Our Shopify Plus migration guide covers what replaces them.

Shopify Functions: your own rules in cart and checkout

Shopify Functions let developers change how Shopify’s backend behaves. Any store can use Functions that come inside public App Store apps, but only Plus stores can use custom apps that contain their own Functions. For conversion work, the useful ones are:

Custom Functions are worth it when an app cannot do exactly what you need, or when several apps are each adding scripts to your store. Fewer apps usually means a faster store, which helps conversion on its own.

How to A/B test on Shopify Plus

Shopify launched Rollouts in March 2026 and extended it in June 2026. It lives under Markets in the Shopify admin and lets you schedule, gradually publish and A/B test changes to your theme, checkout and customer accounts, discounts and product catalogues. There are three types: a Launch makes a change permanent, an Event publishes a change for a set period and then rolls it back, and an Experiment compares a change with your current store before you launch it.

Some limits to know before relying on it:

• Experiments need the Grow plan or above, and targeting a rollout to specific markets needs Advanced or Plus.
• Theme, checkout and accounts changes apply to the online store only. Headless and custom storefront checkouts are not supported, and Shopify POS and headless visitors are left out of the results.
• Vintage themes are not supported, so you need an Online Store 2.0 theme.
• Prices and products can differ between channels while an experiment is running, which matters if you sell on marketplaces or in shops too.

Testing apps such as Shoplift and Intelligems are still useful for things Rollouts does not cover, such as more detailed price and shipping tests, or reporting you want to break down in more ways. Whichever tool you use, the maths is the same.

How much traffic you need

Plus stores usually have the traffic to test, but only for changes big enough to move the numbers. The chart shows how long a simple A/B test takes to detect a 10% relative lift for a store converting at 2%.

To detect a 10% lift you need about 80,700 visitors in each version, so around 161,000 sessions in total. A 20% lift needs about a quarter of that, and a 5% lift needs about four times as much. That is why small tweaks such as button colours rarely produce a readable result, even on a busy Plus store. Test changes that alter what a customer sees or decides, and run each test for at least two full weeks so that weekdays and weekends are both included. You can check any test with Evan Miller’s free sample size calculator.

Where to start: a CRO plan for a Shopify Plus store

1. Measure the funnel. Use Shopify’s analytics and GA4 to see how many sessions reach a product page, add to cart, reach checkout and complete an order, split by device. The biggest drop is usually where to look first.
2. Fix what is broken before testing anything. Slow pages, apps loading scripts you no longer use, broken filters, mobile layout problems and tracking gaps all cost sales and do not need a test to justify fixing.
3. Research why people leave. Session recordings, on site surveys, customer service questions and reviews tell you what customers are unsure about. Baymard Institute puts the average documented cart abandonment rate at 70.22%, and our UK eCommerce statistics page lists the reasons shoppers give.
4. Test the big ideas first. Product page layout, delivery messaging, navigation and search, bundles and offers. Use Rollouts or a testing app, and write down what you expect to happen before you start.
5. Then work on checkout. Add checkout extensions one at a time and test them, starting with delivery information and reassurance, which answer common questions at that point.

What to test first on a Shopify Plus store

Common mistakes

• Testing small tweaks. They need more traffic than most stores have, so the test ends with no answer.
• Stopping a test as soon as it looks like it has won. Early results swing a lot. Decide the sample size before you start and wait for it.
• Testing through a sale or launch. Peak trading changes who is shopping and why. Use Rollouts Events to schedule the sale itself, and keep experiments for normal weeks.
• Adding app after app. Each one can add weight to the store. Check speed after every install.
• Ignoring mobile. Ofcom found smartphones account for most of the time UK adults spend online, so review and test on mobile first.
• Forgetting headless. If your storefront is headless, Shopify’s native experiments do not cover it, so you will need a different testing approach.

Doing it in house or getting help

A Plus brand with a developer and someone who owns analytics can run a lot of this in house, especially now that Rollouts is built in. The work that usually needs specialist help is research, checkout extensions and Functions, which need a developer, and reading test results correctly. Our guide to what a CRO agency does explains what a programme looks like month by month, and our Shopify CRO team works with Plus brands on research, testing and checkout. If you are still deciding whether to upgrade, our Shopify Plus agency page covers builds and migrations.

Frequently asked questions

Related reading: What is Shopify Plus?, What is a good eCommerce conversion rate?, Shopify Flow on Shopify Plus and Shopify Plus pricing.