The Amazfit Helio Ring is one of the more tempting smart rings on the market right now. It costs $149.99, it does not require a subscription, and it tracks sleep, readiness and recovery in a titanium shell that weighs under four grams. There is a catch, though, and it is an unusual one: the ring only comes in three sizes. For a lot of people, that single fact will decide the purchase before any of the other specs matter. Here is our full review, starting with the sizing issue, then battery life, the subscription small print, and who the Helio Ring is genuinely a good fit for.
Disclosure: Fitcoin is our product. We are not affiliated with Whoop, Oura, Google, Fitbit, Garmin, Polar, Amazfit, Xiaomi, Samsung, Suunto, Apple, Huawei, Hume Health or any other brand named on this page. We do not sell trackers and we take no affiliate commission. Where Fitcoin appears, it is as the rewards and insights app that reads the data these devices and workouts write to Apple Health or Health Connect. Everything below is a wellness estimate for general fitness, not medical advice.
The verdict
If your finger is a genuine size 8, 10 or 12 on Amazfit's chart, the Helio Ring is a very good deal: a capable sleep and readiness ring for $149.99 with no monthly fee, which works out to a fraction of what three years with an Oura costs. Battery life is closer to three or four days than a week, sport tracking is minimal, and Oura remains the more polished night-time instrument. If your finger falls between Amazfit's sizes, the right answer is a different ring, because a ring that spins or pinches will not track anything reliably.
Check the sizing first
Amazfit's size chart, which uses a simple string-around-the-finger method, lists three inner circumferences. Size 8 is 60.3 millimetres, or 2.37 inches. Size 10 is 66 millimetres, or 2.6 inches. Size 12 is 71.3 millimetres, or 2.8 inches. The variant picker on the same store page labels those sizes as 24, 25.7 and 27.3 millimetre diameters, which is a different measurement and does not quite convert to the circumferences by ordinary geometry. Our advice is to go by the circumference table and the string method, and treat the diameter labels as a secondary reference until Amazfit clarifies them.
The gaps between sizes are the real issue. There is no size 9 between 60.3 and 66 millimetres, no size 11 between 66 and 71.3, and nothing at all below 60.3. By comparison, Oura sells the Ring 5 in every size from 6 to 13. If you have a smaller hand, or you already know you are an odd size from another ring, the Helio Ring simply does not come in your size, and wearing a loose one is not a workaround. A ring that rotates will not read heart rate properly overnight, which is the main reason to own one, and a ring that is too tight will be off your hand by midweek. If the string says you are between sizes, that is a clear signal to look at a different brand.
The ring itself is titanium alloy on the outside with a resin inner, 8 millimetres wide and 2.6 millimetres thick. Weight is listed at 3.65 grams for size 8, 3.75 for size 10 and 3.82 for size 12, although a footnote on the same page rounds the larger sizes up to about 3.8 and 4 grams. Either way it is a light ring. It is not quite as slim as an Oura, and the width is the thing you notice most when you make a fist.
Battery life, and the setting it depends on
Amazfit rates typical battery life at up to four days, and the footnote explains what "typical" means here: heart rate sampled every 10 minutes, assisted sleep tracking on, sleep breathing quality off, stress checked every 10 minutes, and blood oxygen tracking off. Switch on SpO2, or increase the sampling frequency, and you will land below four days. Charging is wireless and takes about an hour and forty minutes from empty. The box includes the charging puck and a manual but no USB-C cable, on the reasoning that you probably have one already. You probably do, but it is a slightly odd omission at this price.
There is also a recent firmware development worth knowing about. On 31 October 2026, Gadgets & Wearables reported that firmware 2.9.0.1 enables a feature called HybridCharge, sets automatic heart-rate sampling to every 10 minutes by default, and increases stress monitoring to every 5 minutes. We have not run that firmware ourselves, but if stress sampling really has doubled, the four-day estimate that assumed 10-minute intervals is likely to be a little optimistic. Amazfit's own product page includes customer reviews describing the battery as "about three days" and "a few days," so a realistic expectation is three to four days depending on your settings.
Water resistance is 10 ATM under ISO 22810, which Amazfit says covers swimming but not saunas or hot showers, so take it off for those. The sensor package is Amazfit's BioTracker optical module with a dual-colour LED and two photodetectors, plus skin temperature, EDA for stress, an accelerometer and a gyroscope. There is no ECG.
The subscription situation, read carefully
Amazfit's product page says no subscription is required, and that Zepp Aura Premium, which includes sleep sounds, weekly and monthly sleep reports and an AI chat assistant, is free for Helio Ring owners. Further down, footnote 3 notes that readiness insights require a Zepp Aura subscription, and footnote 4 limits Aura availability to a list of countries that includes the United States and United Kingdom, with Canada listed for Aura only.
Putting those together, the fair reading is that the insights which make a ring worth wearing live inside Aura, and Amazfit's offer is that Aura is included free for this ring in the supported countries. You should not end up paying a second bill. If the app ever prompts you for one, that would contradict the product page, and a screenshot of the prompt is worth more than any forum debate. The readiness score itself is built from sleep resting heart rate, sleep HRV, breathing quality and temperature, which is the same broad recipe Oura and others use.
The sport side is where the Helio Ring is clearly thinner. Amazfit lists four sport modes, race time predictions that need at least one 3 kilometre run on record, and sync to Apple Health, Strava, adidas Running, komoot and a few other services. Four modes tells you the priority: this is a sleep and recovery ring that can pair with an Amazfit watch for workouts, not a replacement for one. Zepp Coach Premium appears as a separate line item, and we would not assume it is included just because Aura is. Check the toggle in the app before you build a training plan around it.
Who the Helio Ring is right for
Buy it if your finger genuinely matches a size 8, 10 or 12 on the circumference chart, you want a ring under $150, and you would rather not pay Oura's $5.99 a month. The maths is compelling: three years with an Oura Ring 5 at $399 plus membership comes to more than $600, while three years with a Helio Ring, assuming Aura stays free, is $149.99 and a charger you plug in every few days. For a lot of people that difference is the whole decision.
Skip it if you are between sizes, if you want a week of battery, or if accurate sleep staging is the single most important thing you want from a ring. Oura is still the more convincing night-time tracker, which is where our Ring 5 review lands, and the membership is the price of that. RingConn is the other subscription-free ring people cross-shop when the Helio size chart does not work for them, and our sleep tracking rings guide and Oura alternatives roundup cover the wider market. Garmin's rumoured Cirqa ring is still just a regulatory filing at this point, so it is not something to wait for.
Phone compatibility is straightforward: Amazfit lists Android 7 and iOS 14 or later through the Zepp app. And as with every ring in this category, Amazfit is clear that it is not a medical device. A readiness score is a helpful nudge from a four-gram piece of titanium, and it is fine to take it as a suggestion rather than an instruction.
Sources: Amazfit's US Helio Ring product page, including the size chart, technical specifications and footnotes 3, 4, 8 and 9, checked 2 November 2026. The 31 October firmware details are from Gadgets & Wearables' report. Prices are Amazfit's list prices. We have not run a polysomnography comparison on the ring's sleep tracking.
If the size chart does not work for you: Oura Ring 5 review, Oura alternatives, sleep tracking rings, Oura vs RingConn.
Frequently asked questions
Does the Amazfit Helio Ring need a subscription?
No. Amazfit includes Zepp Aura Premium free for Helio Ring owners in supported countries, including the US and UK, and that is where the readiness insights live. You should not need to pay a monthly fee. Zepp Coach Premium is listed separately, so check in the app before assuming it is included.
What sizes does the Helio Ring come in?
Only three: size 8 (60.3 mm circumference), size 10 (66 mm) and size 12 (71.3 mm). There are no sizes 9 or 11 and nothing smaller than 8. If your finger measures between those sizes, we recommend a different ring, as a loose or tight fit will hurt tracking accuracy.
How long does the Helio Ring battery last?
Amazfit rates it at up to four days with heart rate and stress sampled every 10 minutes and blood oxygen off. Real-world reports and recent firmware changes suggest three to four days is a realistic expectation. Charging takes about an hour and forty minutes.
Does the Helio Ring work with iPhone?
Yes. It works with iOS 14 and later, and Android 7 and later, through the Zepp app. The app can sync data to Apple Health, Strava, adidas Running and komoot.
Is the Helio Ring better than the Oura Ring 5?
It is much cheaper over time, with no subscription and a $149.99 price against Oura's $399 plus $5.99 a month. Oura offers more sizes, longer battery life and more refined sleep tracking. If the Helio fits you and you want to avoid a monthly fee, it is the better value; if you want the most polished sleep data, Oura still leads.
About the author: Harris Khan is the co-founder and CTO of Fitcoin, a UK fitness-rewards and health-insights app that reads Apple Health and Health Connect.