Square vs. Zettle vs. SumUp: compare the UK's best card readers

It’s easier than ever to accept credit and debit cards. Forget the costly card machines of yore. Instead, check out these contactless card readers that process payments with a smartphone or tablet through easy-to-use, free point of sale (POS) apps.

In 2021, the race between the most popular mobile card readers in the UK is close. On our top three list, cost-conscious start-ups often prefer SumUp’s lowest transaction fee. Zettle’s card reader is simply the most loved while Square has the most superior free card reader app.

The three systems share characteristics that make them very attractive to small businesses. Setup costs are very low, and there are no fixed, monthly fees and no minimum transaction volume required. Plus: there’s no contractual commitment with any of these companies.

SumUp Air, Zettle Reader and Square Reader are therefore suitable both for infrequent use and processing many transactions daily as your primary POS solution.

Cards, payouts and charges

As against a traditional card reader machine, you purchase the mobile card readers for a low price with no rental charges or lock-in to worry about.

Zettle currently accepts the most payment cards. On top of Visa, Mastercard and American Express accepted by all three, Zettle can handle Diners Club, JCB, Discover and UnionPay. SumUp also accepts Diners Club, Discover and UnionPay, but not JCB.

Zettle and Square charge a fixed percentage (1.75%) for all chip and contactless card transactions, but SumUp offers the lowest card rate at a fixed , beating Zettle and Square by 0.06 percentage points. All of these fees apply to any credit and debit card, including foreign-issued and p
remium brands like Amex.

With SumUp, settlement takes up to three working days. Zettle and Square will deposit funds in your bank account slightly faster, within one or two working days.

In addition, Square offers Instant Transfers, a voluntary setting that clears transactions in your bank account within 20 minutes at an additional cost of 1% per transaction. To compete, SumUp Card (prepaid Mastercard) gives you access to SumUp Air transactions within 24 hours, even on weekends – and for free.

Point of sale features

All three card readers work with iPad, iPhone and Android tablets or phones, provided the associated payment app is downloaded and connected over Bluetooth.

The inventory libraries in each app look neat with images and product information so you can sell different sizes and types of each item. Square’s app, called Point of Sale, beats Zettle and SumUp with additional features like split bills, custom employee permissions (costing extra) and much more.

Zettle’s POS features come at a close second, with physical gift card options, stock counts, barcode scanning via the phone camera, and more. The SumUp app has slightly fewer POS features, but more remote payment methods.

It is possible to use any of the card readers with more complex POS software so you are not limited to the free apps.

Square users can subscribe to Square for Retail or Square for Restaurants for advanced till features, or a few excellent till systems like Vend and TouchBistro. Zettle’s only upgrade is the Food & Drink app for small cafés, food trucks or similar, but Zettle Reader is compatible with many leading POS systems. SumUp doesn’t have its own POS upgrade, but can integrate with certain other POS systems.