Technology
How does tap to pay work?
You hold a card, a phone or a watch near the terminal, it beeps, and you have paid. Two technologies make that possible: a short-range radio called NFC, and payment tokens that stand in for your card number. A payment ring uses the same two, in far less space.
In short. Contactless payment uses NFC, a radio at 13.56 MHz that works over a couple of centimetres; the terminal’s field can even power a card that has no battery. Phones, watches and rings usually pay with a payment token, a stand-in for your card number that can be tied to one device, so the real number stays out of the shop’s hands. In the EU, small contactless payments can skip the PIN, within limits set by law.
The radio: NFC
Near Field Communication is a short-range radio standard. The NFC Forum, the industry body behind it, describes it as working at a base frequency of 13.56 MHz, with a typical range of up to about 2 cm and data rates from 46 kbit/s up to 1.7 Mbit/s.
- Short on purpose. A range of a couple of centimetres means you pay when you choose to hold the card or device there, not when you walk past.
- Power through the air. One side can power the other through the field, which is how a plastic card with no battery can answer the terminal.
- Metal gets in the way. A device needs an antenna where the radio can get out, which shapes what smart rings are made of: smart ring materials.
The number: payment tokens
Your card number, the primary account number, is the most valuable thing a fraudster can steal. EMVCo, the body that manages the global chip-payment specifications, describes payment tokenisation as replacing that number with a different value, the payment token, which is limited in how it can be used: for example to a specific merchant, device or payment channel.
That is why adding a card to a phone, a watch or a ring involves your bank: it issues a token for that device. If the device is lost, the token can be switched off without changing your card.
The rules: when you need a PIN
In the EU, contactless payments under a set amount can go through without a PIN, up to a running total or a number of payments in a row, after which the bank asks you to confirm. The exact figures come from an EU regulation and the bank’s own settings: paying with a ring has them.
Cards, phones, watches and rings
| How you confirm it is you | Good to know | |
|---|---|---|
| Card | PIN above the contactless limits | Works with no battery |
| Phone | Unlocking the phone | Needs charge, and the phone in your hand |
| Watch or ring | Usually being worn and unlocked since you put it on | Needs a payment partner and your bank’s support |
Tap to pay on Lychnos Ring
Tap to pay is planned for Lychnos Ring through a payment partner, so you can hold your hand to the terminal and leave the phone in your bag. It needs your bank’s own approval and support. It is in development: pay with a ring. Where paying in Europe is heading, from instant transfers to a digital euro: the future of payments in Europe.
Sources, read 4 November 2026: NFC Forum, NFC technology: technical overview; EMVCo, EMV payment tokenisation. General information.
Questions
How close does a card need to be for tap to pay?
Very close: NFC, the radio behind contactless payment, has a typical range of up to about 2 cm, according to the NFC Forum. That short range is part of the design.
Does a phone or watch send my card number when I tap?
Phone and wearable wallets typically use a payment token instead: a stand-in value that replaces your card number and can be limited to one device, merchant or channel, so a stolen token is worth less than a stolen card number.