Most card reader guides are optimised for volume. The more you process, the more a lower per-transaction rate matters, and the more a monthly fee starts to look attractive. That logic only works if you already know what you take in cards each month.
If you’re just starting out, switching from cash, or adding a second income stream, the numbers are murkier. This guide works through every decision in order, so you can figure out what actually matters for your situation rather than defaulting to the most-reviewed option on Amazon.
What type of card reader do you actually need?
There are three categories. Which one fits depends almost entirely on how and where you take payments.
Mobile card readers are small Bluetooth devices that pair with your phone or tablet. You download an app, connect the reader, and you’re ready. Square Reader and SumUp Air are the most common. They cost between £19 and £79, carry no monthly fee, and charge a flat percentage per transaction (usually 1.69–1.75%). Good for low-to-medium volume businesses that don’t need a receipt printer.
Standalone portable terminals are all-in-one devices with their own screen, keypad and SIM card, no phone required. myPOS Go 2 is the clearest example: £29, runs on 4G, settles into a Visa account on the device. Better for market traders, mobile workers, or anyone who doesn’t want to depend on their phone battery mid-job.
Countertop terminals are fixed machines connected via WiFi or Ethernet. Worldpay and Barclaycard Smartpay Anywhere are typical. Faster for high-volume situations like a busy café or retail counter, but usually come with monthly fees or rental costs.
If you’re not sure, start with a mobile reader. You can upgrade later without having wasted much money.
Working out the fees
Fees are where people get confused, and where providers make money on customers who don’t do the arithmetic.
Two main pricing models.
Pay-as-you-go: no monthly fee, but a higher percentage per transaction. Square charges 1.75%. SumUp charges 1.69%. On a £50 transaction you’re paying around 85p–88p. That adds up fast at volume, but costs nothing when trade is slow.
Monthly subscription: a fixed monthly fee in exchange for a lower transaction rate. SumUp One is £19/month and drops the rate to 0.99%. Takepayments has tailored pricing that typically works out cheaper once you’re above roughly £3,000–5,000/month in card sales.
The crossover point for SumUp is around £2,000/month in card revenue. Below that, pay-as-you-go wins. Above it, the subscription saves you money.
Work out your rough monthly card turnover, then run the numbers on two or three providers using their published rates. It takes ten minutes and is the most useful thing you can do before choosing. For a detailed breakdown, see our guide to card reader fees.
Contract length and what you’re actually committing to
Mobile readers from Square, SumUp, Zettle and myPOS have no contract. Buy the hardware, start taking payments. If it doesn’t work out, you stop. No exit fees.
Providers like Worldpay and Takepayments sometimes use 12–18 month contracts, particularly if you’re getting a countertop terminal or a tailored rate. The trade-off is usually a lower per-transaction fee or a terminal included in the monthly cost.
For most businesses starting out, no-contract is the better choice. The flexibility matters more than the marginal fee saving, especially in year one when you don’t yet know what your volume will look like.
How quickly do you need the money?
Most providers settle payments into your bank account within one to three working days. Fine for most businesses.
If cash flow is tight, settlement speed is worth checking specifically. myPOS settles instantly into its own Visa account that you can spend from straight away. Dojo Go and some Barclaycard plans offer next-day settlement. Square typically settles in one to two business days.
If you’re running a business where you need the money the same day — a market stall covering stock costs, a tradesperson buying materials — instant or next-day settlement is worth paying slightly more for.
What happens if the signal drops?
Mobile readers that pair with your phone use your phone’s data connection. No signal, no transaction. That’s a real problem for outdoor events, rural locations, or basements.
Standalone terminals with 4G SIM cards (myPOS, some Takepayments hardware) handle this better. They can roam between networks to find a signal rather than depending on one connection.
Some readers have offline mode — they store transactions locally and process them when connectivity is restored. It sounds useful but has a catch: if a card is declined when the connection comes back, you’ve already handed over the goods. Treat offline mode as a last resort, not a plan.
Before choosing, think about where you actually take most of your payments. A coffee shop with reliable WiFi has very different needs from a builder working on rural new-builds.
Does it need to integrate with anything?
If you use accounting software, Xero, QuickBooks, FreeAgent, check whether the card reader app can sync transactions directly. Square and SumUp both integrate with the main platforms. It saves a significant amount of manual reconciliation.
If you have an online shop, Square is worth looking at: its POS software and online checkout share the same inventory system, so stock levels update automatically whether the sale happens in person or online.
For hospitality businesses using a specific EPOS or booking system, check integration compatibility before committing. Not all card readers connect cleanly to all POS systems.
Receipt printing
Most app-based mobile readers send digital receipts by SMS or email. That’s fine for most customers.
If your business regularly needs printed receipts — trades work, market sales, customers who want a paper record — you’ll need either a reader with a built-in printer (Takepayments Plus has one) or a separate Bluetooth receipt printer. Don’t assume printing is available. Check specifically.
Security and PCI compliance
All UK card readers from reputable providers are PCI DSS compliant. You don’t need to do anything to achieve this beyond using the hardware and software as supplied.
It gets slightly more involved if you also take card payments online or over the phone. In that case, your provider may ask you to complete a Self-Assessment Questionnaire (SAQ) annually. It’s not complicated, but worth knowing about before you’re asked. See our [guide to card reader fees and compliance →] for the full picture.
What most small businesses should do
For a new or early-stage small business:
- Start with Square or SumUp Air. Both are around £19–39, no monthly fee, no contract, and you’ll be set up the same day.
- Move to a subscription plan once your monthly card turnover consistently exceeds £2,000. SumUp One at £19/month or Takepayments at tailored rates will save you money at that level.
- Consider a standalone terminal (myPOS, Dojo) if you work outdoors, have unreliable connectivity, or need next-day cash in your account.
- Look at Barclaycard or Worldpay once you’re at a scale where negotiating rates makes sense, typically £5,000+ per month.
For a detailed look at which providers stand out at each level, see our guide to the best card readers for small businesses.
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