Guide
How to choose a smart ring.
Smart rings now do very different jobs: some track sleep and health, some record voice notes, some answer you. Start with the job you want done; most of the checklist follows from it.
In short. Decide first what the ring is for: health, voice notes or an assistant. Then check the fit, the battery, the monthly plan, whether it needs your phone nearby, what it is made of and how much water it takes. Buying online in the EU, you have 14 days to change your mind and at least two years of legal guarantee.
First: what is it for?
- Health rings track sleep, heart rate and activity, and show the results in a phone app.
- Voice-note rings record what you say and send it to an app on your phone.
- Assistant rings answer you on the ring itself and can act when you agree.
A ring that does one of these well is better than one that does all three badly. More in what an AI ring is, and the rings side by side in AI rings compared.
The checklist
| Question | Why it matters | Lychnos Ring (in development) |
|---|---|---|
| Does it need your phone nearby? | If so, it is the phone’s remote control | Only to set it up; then its own eSIM |
| Where do answers appear? | On the ring, in earbuds or in an app | A see-through screen and a speaker at your ear |
| Is there a plan, and what works without it? | A ring with its own connection or cloud has running costs | The Lychnos plan: €9.99 a month for the first buyers for the first 12 months, later expected at €14.99 to €19.99 |
| How many days on a charge? | Rings that talk or measure all day use more | Target 4 to 7 days, to be measured |
| Which sizes? | A smart ring cannot be resized later | US 6 to 13 |
| What is it made of? | Weight, scratches and whether radios get out | Resin, no metal |
| How much water does it take? | Hand washing, showers, swimming | Sealed, with IP68 as the target for hand washing, showers and rain; the measured rating comes with the final specifications |
| When is the microphone on? | All day, or only when you ask | Only while you hold the button |
| What if the company changes course? | Rings outlive business plans | Firmware, app and protocol planned under Apache-2.0 |
Battery life in detail: smart ring battery life. Why rings like ours need a plan: why an AI ring needs a plan.
Get the size right
Measure the finger and hand you will wear it on, in the afternoon or evening when fingers are a little larger, and not with cold hands. A smart ring is wider than most jewellery, so between two sizes the larger one is usually more comfortable. The ring size calculator converts millimetres into sizes; the ring size guide explains how to measure.
Water ratings, briefly
Makers state water resistance as an IP rating (such as IP68) or in atmospheres (such as 5 ATM). Neither tells you everything: ask whether the maker allows showers, swimming, hot water and soap, and whether water damage is covered. More in IP68 or 5 ATM?
Your rights when you buy in the EU
- 14 days to change your mind for most purchases made online or by phone, counted from delivery, without giving a reason.
- At least two years of legal guarantee against the seller if the ring is faulty, whatever extra warranty the maker offers.
- A pre-order is not yet a purchase. Read what the deposit is for and when you get it back; ours will be refundable in full until you pay the rest.
Where Lychnos Ring stands
Lychnos Ring is an assistant ring: it is built to answer you on your finger, over its own eSIM, and to ask before it acts. It does not track health on its first model. It is in development, for Europe first; see the AI ring you talk to.
Sources, read 4 November 2026: Your Europe, returns and the right of withdrawal and guarantees on goods bought in the EU. General information, not legal advice.
Questions
How do I find my smart ring size?
Measure the finger you will wear it on, ideally in the afternoon, and when in doubt choose the larger size: a smart ring is wider than most jewellery. Our ring size calculator turns millimetres into US, EU and UK sizes.
Can I return a smart ring bought online in the EU?
Usually yes. For most online purchases in the EU you have 14 days from delivery to withdraw without giving a reason, and a legal guarantee of at least two years against the seller if the ring is faulty.