Payment terminals for job sites 2026: Square vs SumUp vs Zettle (offline tested)

SumUp

Square

Zettle

Stripe Terminal

Why offline matters for trades

Rural callouts are where most card readers quietly fail.

Cashless payments are now the norm. Customers ask before they even open the door. The trouble is, the demo videos for every card reader on the market are shot on a counter, on full WiFi, with a fresh battery. None of that matches a Tuesday in a 1930s semi where your data drops the moment you step into the kitchen.

The four readers we tested behave very differently when the signal goes. SumUp Solo carries its own SIM. Square has a 24-hour offline queue on the app. Zettle simply declines if it cannot reach the internet. Stripe Terminal needs WiFi or Ethernet for the WisePOS E, and a tethered phone for the WisePad 3. Knowing which one you have in your hand changes whether you go home with money in the bank or a chasing job for next Tuesday.

For the rest of this guide I am ignoring the marketing pages and using what actually happened on three jobs: a basement boiler swap, a new-build first fix in a part of Suffolk where the only bar of signal is on the roof, and a domestic rewire in a Victorian terrace. The pricing is current to early 2026 and pulled from the providers’ UK pages, not from a spec sheet that has been on the internet since 2022. If you have already moved to a payment-first workflow for renewables, our piece on building a renewables payment pipeline with Payaca, Xero and Stripe covers what the back end looks like.

At a glance: fees and hardware

Here are the numbers you actually need before you keep reading. Every fee is the standard pay-as-you-go rate for an in-person card payment in the UK. Subscription tiers exist for SumUp (Payments Plus drops the rate to 0.99% for around £19 per month) and Square (a couple of bolt-on Plus plans for retail and bookings), but the entry-level reader fee is what most sole traders and small firms pay.

How we tested in basements, lofts, and new builds

I gave each reader to a sole-trader engineer over six weeks and asked them to use it on real jobs. No staged demos. Three locations did most of the damage.

The first was a basement boiler replacement in a south London terrace. Signal at street level was four bars on EE; in the boiler cupboard it was nothing. The second was a new-build site near Lavenham in Suffolk where the closest macro cell is more than a mile away. Walking from kitchen to the back garden lost data even on three-network phones. The third was the easy one, a rewire in a Victorian terrace in Sheffield where WiFi was available from the homeowner’s router but the customer wanted to pay before logging in.

Basement boiler swap, no signal. This is where Zettle stopped.

Each reader was set up the same way: a Samsung S23 paired over Bluetooth where required, the official app installed, and a known-good card used as the test transaction. We measured three things on every job: did the payment go through, how long did the first reconciliation appear in the back-office software, and what happened when we walked into a known dead zone mid-transaction.

The boiler swap killed Zettle and the BBPOS WisePad 3 on first contact. Both showed “no connection” and refused to accept the card. SumUp Solo kept working because the SIM is the radio, not the phone. Square’s reader paired to a phone with no signal went into offline mode and accepted the card up to its conservative single-payment cap; the payment cleared an hour later when we drove back to the van.

The new-build was worse. Even SumUp Solo dropped to GPRS speed and took 20 seconds to authorise. The only reader that worked smoothly inside the property was Square in offline mode, paired to a phone with no signal at all. The catch is that Square pushes the risk onto the merchant: if the card is declined when it eventually reconnects, you eat the cost.

The rewire was a draw. All four worked because there was WiFi. The difference came afterwards, when we asked the engineer which app he wanted to keep using.

SumUp Solo: the 4G winner for site work

SumUp Solo has its own SIM so it does not need your phone’s signal.

SumUp’s pitch is “cheapest fees, simplest hardware” and they have stuck to it. The Solo Lite replaces the old Air reader, comes in at £19 + VAT on the current intro offer, and is the entry point most sole traders should look at. The full SumUp Solo, around £65 + VAT depending on bundle, is the one I actually rate for trades because it ships with an embedded SIM and unlimited free data.

The 4G SIM is the headline. You hand the reader to the customer in a basement, the touchscreen wakes up, and the SIM finds a signal independently of the phone in your other pocket. On the new-build site, this was the only standalone reader that kept working room to room. The downside is that the SIM is multi-network but it still needs some mobile coverage. If you are in a complete dead zone it will not help you.

The 1.69% fee is the lowest of the four. On a heating firm doing £120,000 of card payments a year, that is roughly £72 less than Square or Zettle in pure transaction costs. If you are processing more than £2,700 a month on card, the optional Payments Plus subscription at around £19 per month drops the rate to 0.99% and starts paying for itself. Most sole traders will not get there.

Square Reader: the only true offline queue

Square’s £19 reader is the cheapest sensible bit of card hardware in the UK alongside the SumUp Solo Lite. The difference is what sits behind it. Square’s free POS app is the most polished software on this list by quite some margin, and the offline queue is the single feature that separates Square from Zettle on a real site.

Square’s 24-hour offline mode is what makes the £19 reader earn its keep.

Here is how the offline queue actually works. You enable it inside Square POS settings. When the app loses connection it switches to offline mode automatically, accepts contactless and chip-and-PIN transactions up to a conservative limit you set yourself, and stores them on the device. The moment the phone gets back to data or WiFi, the queued payments process. You have 24 hours from the first offline payment to reconnect. After that, anything still queued expires and the money does not arrive.

There are two trade-offs worth being clear about. First, Square pushes the chargeback risk onto you. If a queued card is declined when it finally clears, you wear the cost of the parts and the time. Second, offline mode does not work on the very first generation Square Reader (the white pre-2017 model). The current second-generation reader and the Square Terminal both support it.

On the rewire job, the Square app outscored the others on actually being pleasant to use. Adding a job description, splitting between materials and labour, taking a deposit and sending a receipt by text all happened in the same screen. Square’s free invoicing tier means you can run a small jobbing business off it without paying for a separate quoting tool, although a proper field-service platform is still better at scale. For more on stepping up to that, see our quote-to-invoice playbook for heating engineers.

Zettle: fast payouts, fragile in poor signal

Zettle, now sold as PayPal Point of Sale, is the most established brand on this list. The Reader 2 is £29 + VAT for your first one, £69 + VAT for any subsequent reader, and the transaction fee is 1.75% flat. Battery life is the best in the group, more than nine hours in power-saving mode or roughly 250 transactions on a charge. The screen and chip slot feel a notch above the Square Reader in the hand.

Zettle handles well in the hand. The trouble starts when the signal drops.

The problem is the one Zettle has had for years and PayPal have not fixed: there is no offline mode. The moment your tethered phone loses data, the Zettle app shows “no connection” and refuses card transactions. On the basement boiler swap, the Zettle reader was the first to go and stayed broken until we walked back outside.

What Zettle does well is the back end. Payouts often land the next working day if you are routing through PayPal balance and you can move money to a linked PayPal account instantly. If you sell on eBay or Vinted on the side, Zettle is the obvious choice because everything lives in one PayPal dashboard. Reporting and product-level inventory are also stronger than Square’s on the free tier.

The Trustpilot score is the weakest of the four at 2.8 from over 4,000 reviews. Most of the one-star reviews are about funds being held during PayPal’s anti-fraud checks rather than the reader itself, but it is worth knowing before you commit. If you have a large lump-sum payment land, PayPal can sit on it for up to 21 days under its standard risk policy.

Stripe Terminal: only if you live in Stripe already

Stripe Terminal is the odd one out. It is built for businesses that already process online payments through Stripe and want their in-person card sales in the same dashboard. The hardware is two BBPOS readers: the WisePad 3 at £49 + VAT for a tethered mobile reader, and the WisePOS E at £179 + VAT for a counter terminal with its own touchscreen.

The transaction fee is 1.5% plus 10p per UK card payment, which looks cheaper than the others until you do the maths. On a £50 emergency callout, Stripe is £0.85; Zettle is £0.88; SumUp is £0.85. The 10p makes Stripe more expensive than SumUp on small transactions and roughly the same as Square. Above £100, Stripe pulls ahead on fees. Below £30, it loses.

Stripe Terminal makes sense when your invoicing already runs through Stripe.

Stripe shines if you take deposits or stage payments online and want the in-person element to flow into the same ledger. For installers running through Payaca with Stripe-hosted payment links, the WisePad 3 lets you tap the customer’s card on the final visit and the payment hits the same Stripe balance as the deposit. Reconciliation in Xero or QuickBooks is one row, not two.

The downside is the setup. Stripe Terminal is built for developers. There is no plug-and-play POS app that compares to Square’s. You either build something custom, use a third-party app that supports Stripe Terminal, or run it through a field-service platform that already has it integrated. For a sole trader who just wants to take a card, this is overkill.

Head-to-head: features that matter on a job site

Here is the comparison stripped back to the things that matter when you are kneeling next to a customer’s washing machine and trying to take a card.

Cost calculator: what you actually pay per year

Numbers beat opinions. Below is what each reader costs over twelve months for three real trade businesses we benchmarked. Card volume is the share of total revenue paid by card; the rest is bank transfer, finance, or cash. These are realistic 2026 splits for boiler engineers, electricians, and small builders working domestic.

*Stripe assumes average transaction of £75. Below £30 average ticket, Stripe is more expensive than SumUp because of the 10p per transaction. SumUp Payments Plus subscription is £19/month and only worth it above roughly £2,700/month in card turnover.

AI fraud detection, smart tipping, auto-reconciliation

The newer feature push from all four providers is automation around the actual payment. Worth knowing what is real and what is a marketing badge.

AI fraud detection. Stripe Radar is the most genuine of the four. It is the same engine Stripe uses to score online card transactions, exposed to in-person sales via Stripe Terminal. It reduces fraudulent chargebacks measurably and learns from your specific transaction patterns. Square and PayPal both run their own fraud engines; Square’s is decent, PayPal’s is the reason large payments sometimes get held. SumUp is the weakest here, with limited risk scoring on the standard plan.

Smart tipping. Useful for hairdressers, less so for trades, but worth a mention if your engineers ever get offered a drink-money tip on a finished install. Square and Zettle both support tipping prompts on the reader itself. SumUp added it to the Solo touchscreen in 2024. Stripe Terminal supports it but needs custom configuration in the app build.

Auto-reconciliation. This is the one most trades will notice. Square and Zettle both push transactions into Xero or QuickBooks directly with named line items. SumUp uses a connector via SumUp Invoices or an integration like Zapier. Stripe is the cleanest of all if your invoicing is already on Stripe links, because the payment and the invoice already share an ID. If you are running a job management platform, our pieces on building a zero-touch invoice pipeline with ServiceM8 and Xero and setting up Tradify, Xero and Stripe in one afternoon are good starting points.

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My verdict