A smart ring is a compact wearable electronic device that combines mobile technology with features for convenient on-the-go use. These devices, typically designed to fit on a finger like a traditional jewelry ring, can offer functionalities like mobile payments, access control, gesture control, and activity tracking. Their most common feature is near-field communication (NFC), providing similar capability to what is built into many smart cards such as credit cards and employee security badges. Thus, they can be used for identification and payments.

Smart rings can connect to smartphones or other devices, and some can operate independently, communicating with cloud-based systems or performing standalone tasks. While lacking traditional displays, they respond to contextual cues, such as proximity to payment terminals or specific gestures.^[1]

In 2013, the British company McLear, co-founded by John McLear, Chris Leach, and Joe Prencipe, introduced the first commercially available smart ring.^{[2][failed verification]} Today, a multitude of companies produce smart rings for various use cases, expanding the options available to consumers.

A prominent feature of smart rings is their ability to function as near-field communication devices, providing an alternative to carrying traditional items such as credit cards, door keys, car keys, and potentially even ID cards or driver's licenses.^[3][4] Additionally, these rings can connect to smartphones, serving as notification devices for incoming calls, text messages, emails, and other alerts. They can also act as gesture-based controllers, enabling users to perform various actions with simple hand motions. Furthermore, smart rings offer the capability to track health-related metrics, including steps taken, distance travelled, sleep patterns, heart rate, and calorie consumption.^[5][6]

Secure access control such as for company entry and exit, home access, cars, and electronic devices was the first use of smart rings. Smart rings change the status quo for secure access control by increasing ease of use, decreasing physical security flaws such as by ease of losing the device, and by adding two-factor authentication mechanisms including biometrics and key code entry.

Smart rings can perform payments and metro ticketing similar to contactless cards, smart cards, and mobile phones. Security of the transaction is equal to or greater than contactless cards. The first smart ring to be created with contactless payments was the NFC Payment Ring, which was mass produced and unveiled at the Olympics Summer Games at Rio de Janeiro in August 2016.^[7]

Similar to smartwatches, smart rings utilise in-built sensors to provide activity and wellness tracking. For example, step and heart beat tracking,^[8] temperature and sleep tracking (through measuring heart beats and movements) and blood flow.^[9] The smart ring form factor contains enough space to contain the same components as smartwatches. However, due to size constraints, smaller components are typically used in current smart ring products in the market, such as smaller and less accurate accelerometers, and smaller batteries leading to lower battery life than smartwatches.^[10]

Through the use of a small microphone, or bone conduction, some smart rings can allow the wearer to make phone calls while paired with a compatible mobile phone.^[11] Smart rings are also able to notify the wearer of incoming calls and messages, by means of vibrating or lighting up.^[12]

Additionally, some smart rings allow the wearer to see and feel real-time heartbeat of the 2nd smart ring wearer, where the heartbeat is displayed on the ring similarly by means of lighting up and vibrations.^[13] Such smart rings require connection to a smartphone with active data or Wi-Fi connection to allow the transfer of data between two smart rings. The idea behind such function is to advance on a premise known as vena amoris and serve as a digital alternative to classic wedding or engagement rings.^[14]

Smart rings provide social feedback to users and can be used to engage in the user's environment in a way that other wearables and mobile devices do not permit. Some smart rings provide notifications (e.g. lights or vibrations) to notify the user when they receive a text message, phone call, or other notification. This enables the user to be aware of the notification without having to constantly check their smartphone.

• Smartwatch
• Wearable computer
• Personal organizer
• Near-field communication
• Oura Health
• Ultrahuman