Klaviyo vs Mailchimp vs Omnisend: Best for UK Shopify

For most UK Shopify stores, Klaviyo is the most powerful and the industry default once you take email marketing seriously, Omnisend is the best value for stores under £20k/month that want email plus SMS in one bill, and Mailchimp now works properly with Shopify again after their 2019 fallout but still trails on e-commerce depth. As a rough rule: Omnisend for early-stage Shopify, Klaviyo the moment revenue starts to compound, Mailchimp only if you are already invested in it or you sell services alongside products.

Klaviyo vs Mailchimp vs Omnisend at a glance

Sources: klaviyo.com/pricing, mailchimp.com/pricing, omnisend.com/pricing.

Why does this comparison matter for a UK Shopify store?

Email is the single highest-ROI marketing channel for a small e-commerce business. Ads get more expensive every year; email is a channel you own. The question is not "should I do email marketing" — it is "which platform will not become a bottleneck as I grow."

The wrong choice costs you in three ways:

• Migration pain — moving lists, templates, and flows between platforms is a week of work
• Feature ceilings — cheaper tools cap out on automations and segmentation just as they start to matter
• Deliverability — a platform's sending reputation directly affects how many of your emails land in the inbox

We work with UK Shopify stores across all three of these platforms. Here is the honest read.

Klaviyo — the industry default for serious Shopify stores

Klaviyo is now the default recommendation across the Shopify ecosystem for one simple reason: it was built for e-commerce first, and it has the deepest native Shopify integration on the market.

What you get:

• Real-time sync of every Shopify event — orders, products, browsing, checkouts
• Predictive analytics baked in: expected customer lifetime value, churn risk score, next order date
• The strongest segmentation engine in the Shopify space — combine purchase behaviour, engagement, browsing, predicted CLV, and geography in one segment
• Pre-built flows for welcome series, abandoned cart, browse abandon, post-purchase, win-back, replenishment
• Email plus SMS on a single plan (Email + SMS tier) — no juggling two vendors
• Very high deliverability — Klaviyo's shared IPs have a strong sender reputation

Best for:

• Shopify stores doing £20k/month or more in revenue
• Any store where returning customers matter (skincare, food, apparel, subscriptions)
• Founders who want to run sophisticated segmented campaigns without a developer

Limitations:

• The pricing curve gets steep once you cross ~10,000 contacts
• Overkill for a store selling one product once a year
• The interface has more depth than a first-time email marketer needs on day one
• SMS pricing is separate on top of the email plan cost if you add heavy SMS volume

Klaviyo Free covers you up to 250 contacts and 500 emails/month, which is enough to learn the tool. Paid plans start at around $20/month for 251–500 profiles and scale up by contact count. See klaviyo.com/pricing for the current tier calculator.

Mailchimp — the reconciled option (but with caveats)

Mailchimp is the platform most non-technical business owners have heard of. That familiarity is its biggest asset. The catch: from 2019 until 2024, Mailchimp and Shopify were in an open feud — Mailchimp was removed from the Shopify App Store and stores had to bolt integrations together with third-party tools. That is now fixed.

What you get:

• Fully restored native Shopify integration since 2024 — customer sync, purchase history, product catalogue, abandoned cart, product recommendations
• The best-looking drag-and-drop template editor of the three
• Solid campaign reporting and A/B testing
• Broad integrations beyond e-commerce (CRM, landing pages, forms, surveys)
• A generative AI content assistant for subject lines and copy

Best for:

• Small businesses that sell services and products (e.g. a café with an online store and a booking system)
• Teams already invested in Mailchimp who do not want to migrate
• Multi-channel marketers who want landing pages, forms, and email in one tool

Limitations:

• E-commerce automations are less deep than Klaviyo or Omnisend — the flows exist but the segmentation logic is less powerful
• SMS is an add-on with credits sold separately, not included in the plan
• Contact counting includes unsubscribed and non-marketing contacts on some plans — the bill grows faster than you expect
• Historical trust deficit with Shopify sellers — many will not go back

Free tier gives you 250 contacts and 500 emails/month. The Standard plan (the tier most Shopify sellers use) runs about $100/month at 5,000 contacts. UK pricing is available in GBP on mailchimp.com/pricing, though promotional discounts on the pricing page can mask the standing rate.

Omnisend — the value pick for Shopify-first businesses

Omnisend was built from day one for e-commerce and, specifically, for Shopify and BigCommerce sellers. It gets less attention than Klaviyo but delivers most of the same core e-commerce automations at a lower price point, with SMS included in the top plan.

What you get:

• Native Shopify integration with product picker built into the email editor
• All the core e-commerce automations: welcome, abandoned cart, browse abandon, post-purchase, back-in-stock
• Email, SMS, and web push in one tool
• Pro plan includes unlimited emails plus SMS credits equal to the plan cost
• Simpler, less intimidating interface than Klaviyo

Best for:

• New Shopify stores under £20k/month in revenue
• Founders who want SMS on day one without a separate contract
• Anyone who finds Klaviyo overwhelming and Mailchimp expensive

Limitations:

• Segmentation is less powerful than Klaviyo (fine for most stores, ceiling for advanced ones)
• Reporting is competent but not as deep as Klaviyo's revenue attribution
• Ecosystem is smaller — fewer third-party integrations and agencies specialise in it
• Fewer template starter designs than Mailchimp

Free tier is 250 contacts and 500 emails/month. Standard plan runs $81/month at 5,000 contacts (up to 60,000 emails). Pro is $90/month at 5,000 contacts with unlimited email plus $90 in SMS credits. See omnisend.com/pricing.

What does each cost in real life?

Let us run the numbers on a real Shopify store: 5,000 email subscribers, 2 campaigns a month, 3 core automations (welcome series, abandoned cart, post-purchase).

Monthly cost per platform (approximate, USD unless stated):

For a UK Shopify store at this size, the annualised difference between the cheapest and most expensive option is roughly £150–£300 a year. That is not a lot in absolute terms, but the more important question is what happens at 20,000 contacts.

At 20,000+ contacts, the picture shifts:

• Klaviyo pricing scales aggressively — plan on $300–$400+/month
• Omnisend stays materially cheaper at this range
• Mailchimp Standard tracks close to Klaviyo but with a weaker feature set for the money

The real question is not "which has the lowest fee at 5,000 contacts" but "which platform will still fit at 50,000, and how much will it cost me to switch if it does not."

What does SME Shack recommend?

For UK Shopify stores we work with, the rule of thumb runs by revenue:

• £0–£5k/month revenue (0–1,000 contacts) → Start on Omnisend or Klaviyo free tier. Learn the tool. Do not pay yet.
• £5k–£20k/month revenue (1,000–5,000 contacts) → Omnisend Standard or Pro. Best value for money, SMS included on Pro, all core automations covered.
• £20k–£100k/month revenue (5,000–20,000 contacts) → Klaviyo Email. The predictive analytics and segmentation start paying for themselves here. Migration cost is worth it.
• £100k/month+ revenue (20,000+ contacts) → Klaviyo Email + SMS. At this scale you want the deepest segmentation and best deliverability. Small percentage improvements in click-through are worth thousands.
• Multi-channel business (products + services + bookings) → Mailchimp. The only one of the three that comfortably handles non-e-com use cases in the same tool.

We also see stores stuck on Mailchimp from years ago paying more than they need to for less than they should get. If you have not audited your plan in 12 months, do it now — Mailchimp's contact counting can quietly push you into the wrong tier.

For a full walkthrough of what we build and manage for Shopify clients, see our digital marketing service — email flows, SMS setup, and monthly reporting are all included in our care plans. If you are still deciding on the shop platform itself, our e-commerce build service covers that too.

Frequently asked questions

Q: Is Klaviyo really worth the extra cost over Omnisend?

A: Once you are over ~5,000 engaged contacts, yes. Klaviyo's segmentation and predictive analytics generate more revenue per email sent than a simpler tool, and that typically covers the price difference several times over. Under 5,000 contacts, the gap is smaller and Omnisend is often the smarter choice.

Q: Can I still use Mailchimp with Shopify in 2026?

A: Yes. Mailchimp and Shopify reconciled in 2024 and the native integration is fully restored. It syncs customers, orders, and products, and supports abandoned cart and product recommendation flows. It is competent — just less deep than Klaviyo's or Omnisend's Shopify-specific tooling.

Q: How much does SMS marketing actually cost on top?

A: SMS is billed per message. Omnisend Pro includes SMS credit equal to your plan cost. Klaviyo Email + SMS bundles a starter credit and then bills per message beyond it. Mailchimp requires you to buy SMS credits separately. UK SMS is roughly 2–4p per message depending on volume — budget £30–£100/month for a typical small store running abandoned cart SMS.

Q: What about deliverability — do these platforms actually land in the inbox?

A: All three have strong sender reputations. Klaviyo is generally regarded as the strongest for e-commerce specifically. Deliverability depends more on how you send — clean lists, engaged subscribers, proper DKIM and SPF setup on your domain — than which platform you pick. Sending to old, disengaged lists on any of these will land you in spam.

Q: How hard is it to migrate from one to another?

A: Contacts and basic templates move in a few hours. Rebuilding automations (flows, segments, popups) is a 2–5 day job depending on complexity. This is why we tell most stores to pick a platform they can grow into for 2–3 years, rather than switching every time the pricing conversation flares up.

Q: What about Klaviyo alternatives like Drip, Sender, or ActiveCampaign?

A: Drip is a solid Klaviyo alternative and slightly cheaper at mid-market. Sender is a strong budget option. ActiveCampaign is powerful but built more for B2B and services businesses than e-commerce. For UK Shopify stores specifically, Klaviyo, Omnisend, and Mailchimp are the three that come up in almost every conversation — the rest are edge cases.