Which contactless payment terminal should you get, and is your phone enough?

Square is the easiest place to start taking tap payments in the US. Download the free point of sale app, turn on Tap to Pay, and your iPhone accepts contactless cards and phones with no hardware at all. When a card asks for a PIN, your screen shows a keypad and the customer enters it there. The ceiling is high: Square lists a $10,000 limit per plastic card on Tap to Pay and $50,000 for a wallet payment.

The fee is 2.6% + 15¢ per in-person sale. On a $12 coffee and pastry, that is about 46 cents, the highest here on small tickets because of the 15-cent fixed fee. On an $80 sale it is $2.23, right in line with the others. If most of your sales are under $15, run the numbers against PayPal POS below.

When the line gets long, a phone stops being enough: you hand it over, it heats up, the battery drains. That is when the $59 contactless and chip reader makes sense, or the $299 Square Terminal with its own screen and printer.

The weak spot is the phone itself. On the Square seller community, Tap to Pay broke after one iOS update until the next patch, and magnetic or wallet cases blocked the NFC chip. Do not update the register phone on a Saturday morning, and take the case off.

PayPal POS (formerly Zettle) has the lowest flat rate in this comparison: 2.29% + 9¢ per in-person payment. On a $12 sale, you pay about 36 cents, ten cents less than Square. Our math: Square's 2.6% + 15¢ is about 10 cents more per $12 sale, so at 2,000 such sales a month the gap is roughly $200.

The first card reader costs $29 for new accounts, then $79 for each extra one. The standalone PayPal POS Terminal starts at $199, or $239 with a barcode scanner. Money lands in your PayPal balance, which helps if you already sell online through PayPal: one balance, one dashboard.

The catch is the Bluetooth link. Seller reviews, many of them a few years old but consistent, mention the reader dropping its connection with the app and taps that fail on the first try. They also praise how fast a tap goes through once everything is paired. Our tip: turn off battery saver on the register phone and charge the reader every night.

We did not find a Tap to Pay offer on PayPal's US point of sale price page. If you want to sell with only your phone, look at Square or Stripe.

Stripe Terminal is not a ready-made register. It is a building block your developer plugs into your own app. In return, in-store and online sales land in the same Stripe account, with the same reports and the same customer records. Tap to Pay works on iPhone and Android, and the M2 reader costs $59, the S700 smart terminal $299.

The pricing is 2.7% + 5¢ per in-person card, plus 1.5% for international cards. Tap to Pay adds 10 cents per payment. On a $12 sale that is 37 cents with the M2 and 47 cents on the phone, the highest in this table for Tap to Pay. On an $80 sale, it is $2.21 with the reader.

So the rule is simple: use the reader for your main counter, and keep Tap to Pay for pop-ups, deliveries and the moment the reader dies. That way the extra 10 cents only applies when it saves a sale.

SumUp charges 2.6% + 10¢ per in-person payment in the US, five cents less per sale than Square. On a $12 ticket that is about 41 cents; on $80, $2.18. There is no monthly fee, and payouts arrive the next day.

SumUp's readers take contactless cards, chip cards and mobile wallets. If you type a card number by hand, the rate climbs to 3.5% + 15¢, so ask customers to tap whenever you can.

Its overall score of 4.1 is the one we give SumUp across all our card reader pages, where hardware and payouts weigh heavily. On contactless specifically, it sits fourth here because we did not find Tap to Pay on its US price page, so you need a reader.

The recurring complaint from sellers is support: it starts with an automated assistant, with no direct phone line. Some also report taps that take a long time to register. If your counter is fast, test the reader at peak hour during the first week.

Helcim does not use a flat rate. You pay interchange (the fee set by the customer's bank and the card network) plus 0.40% and 8 cents per in-person payment, below $50,000 a month. On a debit card tap, that often lands below any flat rate in this table. On a premium rewards card, it can land above.

That is why we cannot give a single figure for a $12 sale: it depends on the card. What we can say is that the markup is small, there is no monthly fee, and Helcim publishes its pricing openly.

The hardware is the downside for a small contactless setup. The Card Reader costs $199 and the Smart Terminal $349, far above Square's $59 reader or PayPal's $29 one. For a market stall doing a few hundred dollars a week, that upfront cost takes a long time to pay back.

Clover makes good hardware: the Clover Go reader takes taps on the go, and the countertop terminals are solid. The problem is how it is sold. Clover often reaches you through a bank or a reseller, with a monthly plan and a processing rate that changes from one seller to the next.

That makes the cost of a single tap hard to compare. Before you sign, ask for three things in writing: the rate per contactless payment, the monthly fee, and the cost of leaving the contract early. If any of the three is missing, compare with Square or PayPal POS, which publish everything.

Its score of 2.9 reflects that lack of freedom, not the hardware.