“Card reader” and “card machine” appear on the same comparison pages, used as though they mean the same thing. Sometimes they do. Often they don’t — and the distinction matters when you’re choosing hardware, because the two types have genuinely different costs, setup requirements, and capabilities.
This guide covers what each term actually refers to, the overlap between them, and what to look for depending on how your business takes payments.
How the terms are used
In everyday usage, the terms blur together. A market trader calling their SumUp a “card machine” isn’t wrong. A retailer describing their Worldpay terminal as a “card reader” isn’t wrong either.
The more useful distinction is by hardware type and how the device works, rather than the name.
Mobile card readers (the smaller devices)
A mobile card reader is a small, portable device — typically the size of a matchbox or slightly larger — that connects to your smartphone or tablet via Bluetooth. It doesn’t work on its own. It pairs with an app on your phone, which handles the transaction processing, receipt sending, and reporting.
Examples: Square Reader 2 (£19 + VAT), SumUp Solo Lite (£25 + VAT), Zettle Reader 2 (£29 + VAT), Barclaycard Smartpay Anywhere (£29 + VAT).
What they do well: they’re cheap, portable, and quick to set up. You can be taking card payments within an hour of ordering one. No engineer visit required, no installation.
What they don’t do: most don’t have a screen, a receipt printer, or any standalone capability. They depend entirely on your phone — if the phone battery dies or the signal drops, payments stop. They’re also not built for high-volume, continuous use in a busy retail or hospitality environment.
Card machines / card terminals (the full devices)
A card terminal — also called a PDQ machine or card machine — is a self-contained device with its own screen, keypad, connectivity (WiFi, 4G, or Ethernet), and often a receipt printer. It doesn’t need a phone to operate.
Examples: Square Terminal (£149 + VAT), SumUp Solo (£79 + VAT), myPOS Go 2 (£29), Worldpay Axium DX8000 (rented), Takepayments Plus (rented), Dojo Go (rented).
What they do well: standalone operation, faster transaction processing, longer battery life (typically 8–10 hours under load), more capable software, and receipt printing on some models. Better suited to continuous use at a counter, in hospitality table service, or for mobile workers who can’t depend on their phone.
What they cost more: upfront (£79–£299 to buy) or as a monthly rental on a contract (typically £15–30/month with 12–18 month agreements).
The overlap: standalone readers with 4G
The line between “mobile card reader” and “card machine” has blurred with devices like myPOS Go 2 and SumUp Solo. Both are small enough to be called readers, but both have their own SIM cards and work independently of a phone. The myPOS Go 2 is physically similar in size to a large matchbox but operates exactly like a full terminal — no phone required, its own 4G, instant settlement.
Hardware size is less of a guide to capability than it used to be.
PDQ machine: what does that mean?
PDQ stands for “Process Data Quickly” — an older industry term for card terminals that predates the modern mobile reader era. You’ll still hear it used, particularly by older providers and in traditional retail or hospitality contexts. It means the same thing as “card terminal” or “card machine.” If a provider’s quote mentions a “PDQ machine,” it refers to a countertop or portable terminal.
Choosing by use case
For most purposes, the question isn’t “reader or machine?” — it’s “what do I actually need the device to do?”
A portable Bluetooth reader is right if: you take occasional or moderate payments, you’re usually near your phone, you work in decent signal coverage, and cost matters at startup. Most sole traders, market traders, and small service businesses are in this category.
A standalone terminal is right if: you need independence from your phone, you need an all-day battery for outdoor or mobile work, you process high volumes at a fixed counter, or you need a receipt printer integrated. Busier cafés, hospitality businesses, and tradespeople doing large-value jobs lean this way.
A full countertop terminal on a contract makes sense if: you have a permanent location, you’re taking consistently high card volumes (typically above £5,000/month), and you want the reliability of enterprise-grade hardware without buying it outright.
Common terminology you’ll see
| Term | What it means |
|---|---|
| Card reader | Usually a small Bluetooth reader paired to a phone, but sometimes used for any payment device |
| Card machine | Usually a standalone terminal, but often used interchangeably with card reader |
| PDQ machine | An older term for any card terminal — same thing |
| mPOS | Mobile Point of Sale — specifically describes phone-paired payment systems |
| Card terminal | A standalone device with its own screen and connectivity |
| EPOS | Electronic Point of Sale — a full business management system that may include a card reader as one component |
Our verdict
For most new small businesses: a mobile card reader is the right starting point. It’s cheap, fast to set up, and sufficient for moderate payment volumes. Upgrade to a standalone terminal once the limitations of phone dependency actually become a problem — which, for many businesses, they never do.
For businesses that already know they need continuous, high-volume, or independent payment processing: skip the entry reader and start with a standalone terminal.
See our how to choose a card reader for a full decision framework, or our best card readers for small businesses to compare specific products.
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