DEV Community: Shradha Puri

Why Smart Rings Could Replace Smartwatches Sooner Than You Think

Shradha Puri — Mon, 27 Apr 2026 10:15:02 +0000

You wake up to find your sleep score already calculated and displayed on your phone, you look up your recovery numbers and leave without considering your phone charger again. No bulky thing strapped around your wrist while working out or attending meetings, no disruptive screen lighting up at night as you try to fall asleep. These are the silent features that make smart rings appealing today and many people cannot help but speculate if smart rings might silently dethrone their bigger counterpart, the smartwatch, sooner than anyone can anticipate.

Wearing a smartwatch has been the trend for years now. They are versatile enough to perform almost all functions, ranging from notification reminders, calling, GPS, music and even payment options. However, it has become increasingly difficult for some people to handle the frequent need for charging the devices and the unnecessary data interruptions they pose. Smart rings are emerging as a simpler alternative, especially for people who care most about their health data without the additional features a smartwatch provides.

The numbers back this up. The smart rings market stood at roughly $400-$700 million in 2025, with an anticipated 25-29% CAGR, reaching several billion by the early 2030s. This represents a much higher growth rate compared to that of smartwatches, which is still huge but growing at a more modest 9-12% pace. In 2025, shipments of smart rings jumped by almost 50%, whereas the corresponding growth rate for smartwatches was approximately 6%. While the leading player is Oura, there is Samsung’s Galaxy Ring and similar competitors such as Ultrahuman and RingConn, making it a real category.

Why the Shift? One Answer? Battery Life

This might be the biggest reason why people make the switch. Most modern smartwatches have to be charged almost daily, if not every other day, depending on which features you use. Even models like Apple Watch Series 11 or Samsung Galaxy may last you for 1-2 days with careful use, however, most of the users just end up charging them overnight anyway.

Smart rings break this trend with ease. The Oura Ring 4 provides an average runtime of 7-8 days before you have to charge. Samsung Galaxy Ring lasts for 5-7 days, while the RingConn pushes the claims to** 10-12 days**. You charge once a week, drop it on a small case or charger while you shower and forget about your battery dying out in the middle of the day or while you travel. That convenience adds up fast when you’re trying to build consistent tracking habits.

The smaller size is what helps here. They use less power overall and focus on efficiency instead of flashy displays and continuous wireless connection.

Better Data for the Things That Matter Most

A lot of the hype around smart rings comes down to the accuracy of the metrics such as sleep data, heart rate, recovery and heart rate variability (HRV). Fingers have thinner skin and arteries closer to the surface than your wrist, making sensors sit more stably without sliding around like a loose watch band.

Users often highlight that smart rings pick up subtle changes better. They include early detection of sickness, trends in stress levels and tracking menstrual stages and cycle predictions. In addition, the sleep stage accuracy ranges from 93-96%, with a strong correlation between heart rate and HRV. Many people report that smart rings feel more reliable for long-term trends than wrist devices, which can get thrown off by movement or how tightly you wear the band.

Unlike wrist devices, smart rings have no screen to disrupt melatonin production at night. It does not have a watch face that could bother you when lying in bed at night. You just wear it and let the app build a picture over weeks and months. That steady and continuous data is what a lot of health focused users actually want.

Comfort and the “Set It and Forget It” Factor

Let’s be honest, carrying a large watch all the time starts to get really old after a while. They tend to catch on clothes, get sweaty during workouts, clash with formal outfits and can feel heavy after a full day. A smart ring is basically like jewelry. It weighs just a couple of grams, disappears on your finger and lets you wear your watch that has been sitting in the box and actually matches your outfit.

Comfort also matters the most for sleep tracking. Many people, including me when I’m not testing a smartwatch for a review, take their watch off before bed simply because it’s annoying, which defeats the purpose. Smart rings stay on comfortably for most users, giving truly continuous data.

Another reason why a smart ring wins over a smartwatch is the ability to remain discreet. Not everyone enjoys showing off their wearable tech and a simple smart ring can help blend in at work, social gatherings or the gym without raising eyebrows. Plus, it allows for passive tracking without constantly checking on the incoming notifications.

What Smart Rings Are Missing (For Now)

Listen, I’m not saying smart rings will kill smartwatches tomorrow. Watches still win on features right now. You get a proper screen for time, notifications, maps or your workout stats, along with a built-in GPS sensor that works while you run without your phone, music control, voice assistants and even payments without carrying your wallet or your phone.

Rings don’t offer any screen, so all information has to be funneled through the corresponding phone app. In most cases, smart rings don’t provide real-time workout coaching or route navigation because that requires displaying information such as GPS directions and heart rate zones in real time on a device screen.

Some smart rings, like Oura Ring, require a monthly payment for full access to insights, while others, like Samsung or Ultrahuman, do not charge anything for basic metrics once the ring is purchased. That pricing matters to most people, including myself, because why would I pay a monthly fee to use something I already paid for?

Battery longevity over many years is yet another point to consider. Some people say that their smart ring became less functional after two years as the capacity drops, though newer models are improving.

Shift That’s Already Happening

An increasing number of users are using both gadgets at once. Wear the watch during daytime activities for various features and GPS, while for sleep monitoring and other measurements, you will use your ring. Others are switching fully to a smart ring completely for a calmer and a reduced screen time experience.

The market is responding. Samsung introduced an ecosystem integration of its Galaxy Ring. Oura constantly improves its artificial intelligence features and readiness scores. The most recent smart rings feature improved sensors, water resistance up to 100m and more design options. In short, they become much more similar to ordinary jewelry.

Monitoring health and fitness is becoming a more private and long-term process. Now, people do not really care about counting every step, but more about recovery and stress levels. Smart rings are just perfect for such purposes.

Where Things Go From Here

Smart rings won’t replace every smartwatch use case. Serious athletes who require real-time coaching and guidance via their devices will most likely continue using smartwatches. Additionally, people who enjoy the concept of having a small computer on their wrist will most likely continue wearing smartwatches.

But for the huge chunk of users will most likely gravitate towards smart rings because they are more affordable and comfortable than smartwatches when worn all day and night. Also, they are far more precise in measuring critical health parameters and are significantly less disruptive. The numbers prove the transition is well underway. Smart rings are becoming mainstream at a faster rate than many industry observers predicted.

If you’re tired of charging every night or feeling like your wrist device controls too much of your attention, a smart ring might be worth trying. Most people who made the switch were surprised by how little they missed the display function on their smartwatches. The data feels cleaner, the wear feels lighter, and the habit sticks easier.

It might not be a total takeover anytime soon, but when it comes to everyday health and wellness tracking, they do make compelling arguments. The future of wearables might look a lot smaller and a lot less demanding than the big watches we got used to.

Understanding Wearable Sensors: What Data You Can Trust

Shradha Puri — Thu, 16 Apr 2026 09:19:08 +0000

After having worn my smartwatch and smart ring nearly every day over the last couple of years, I have found that there is a good balance between appreciating the data on my wrist and viewing it with some healthy skepticism. For example, one morning, my watch will show that I have slept “excellently” and burned a lot of calories from simply taking a walk. The following morning, I feel exhausted despite having recovered “perfectly.”

Sounds familiar?

Most of us bought these devices hoping for accurate readings about our steps, heart rate, sleep and recovery. However, not all sensors give similar results. Some readings are quite good in terms of their accuracy, but others can be described as mere approximations. Based on current research to determine the validity and reliability of these devices as compared to laboratory testing equipment (ECG chest strap, sleep tests), here is a breakdown of what you can actually trust and what data is best taken with a grain of salt.

How Wearable Sensors Actually Work

Most wearable devices rely on a small set of sensors that are the core of all the data we get from our devices.

PPG (Optical Heart Rate Sensors)- PPGs use green, red/infrared light to measure variations in blood volume underneath your skin. These provide HR, RHR, HRV, blood oxygen and recovery data.
Accelerometers and Gyroscopes (Motion Sensors)- These measure movement to track the number of steps, estimate the intensity of activity and differentiate between sleep and awake stages.
Additional Sensors- These include sensors like skin temperature, ECG, EDA or ambient light to detect cycle phases, stress, onset of an illness, readiness score or any more advanced features.

The raw data is then analyzed through an algorithm that produces the graphs and score values we use. The device is remarkable for its small size and the amount of information it packs, but many factors in the real world can affect the accuracy of data.

Heart Rate: Often Reliable, But Not During Chaos

For resting and light daily activity, PPG readings of heart rate from the wrist-worn trackers have proven to be accurate. These usually had an average error of less than 1 BPM in resting conditions. The Apple Watch has consistently performed better and has excellent correlation coefficients; Garmin and other Fitbit trackers also provide reliable HR estimates.

However, for high-intensity exercises, HIIT, resistance training and wrist-intensive activities such as cycling or typing, the accuracy of the PPG measurements significantly drops. Errors increase and many trackers have an absolute deviation of 10-20%+. Multiwavelength sensors have helped mitigate the problem, although recent studies have found that motion artifacts are more influential than skin color differences.

Trust or not: Should be trusted for resting HR and steady state cardio. Best paired with a chest strap for an accurate high-motion workout reading, especially if you’re training for a marathon or are an athlete.

Step Counting: One of the Most Dependable Metrics

Step counting appears to be quite reliable, particularly when walking and running occur under lab conditions. Garmin and Apple Watch can obtain less than 5% accuracy during experiments.

In their “free-living” version, the percentage of inaccuracy amounts to** 6-18%**. Walking, running, pushing a stroller, carrying things and cycling are harder to detect accurately. Since the Oura Ring is finger-based, it may count differently compared to a wrist tracker such as a WHOOP or an Apple Watch.

Trust or not: Very high. Relatively low in the case of non-standard days. For me, it was quite motivating despite inaccuracies in step counts.

Calorie Burn or Energy Expenditure: Treat as a Rough Guide

Calories burned are always a poor indicator in wearable tech. Research indicates mistakes of 20% to 50% or higher since calories cannot be determined directly but must be approximated based on factors such as heartbeat, activity levels, age, body mass index and general algorithms without knowledge of the individual’s metabolism, physical condition and muscle efficiency.

While the Apple Watch usually fares better than most, it still misses by several hundred calories on occasion.

Trust or not: Low when making calculations for everyday life decisions, such as calorie intake.

Sleep Tracking: Strong on Big Picture, Weaker on Details

Sleep/wake detection is another area where wearables, especially smart rings excel. Among various wearables tested by independent researchers, the Oura Ring always scores the highest accuracy (agreement with polysomnography). In one of the studies, the Oura ring 4 demonstrated an excellent Cohen’s kappa of 0.65 for its four-stage analysis (0.60 for Apple Watch, 0.55 for Fitbit), as well as high deep sleep sensitivity (~79.5%).

Yet, all wrist wearables usually overestimate sleep duration and efficiency (by 10-15%), not to mention relatively low accuracy in sleep stage distribution (REM, light, deep).

Trust or not: High for general duration, consistency levels and sleep/wake state. Moderate for a specific percentage per sleep cycle stage. Your “readiness” score for each night only truly comes into context after understanding how it correlates to how you feel the next day.

HRV, SpO2 and Other Metrics

Heart Rate Variability (HRV) and Recovery:

Oura devices excel in this category, particularly at night, where they achieve a high concordance correlation coefficient of up to 0.99 and very low error rates (about 6%) compared to ECGs in 2025 trials.

Blood Oxygen Saturation (SpO2):

Acceptable at rest but susceptible to dropouts when exercising or at high altitudes.

Skin Temperature:

Useful for observing relative fluctuations (disease, menstrual cycle changes) rather than absolute values.

Real-Life Factors That Affect Accuracy

Problems include loose fitting, sweat, tattoos, positioning of the wrist during exercise and the type of movement. Motion artifacts continue to be the problem despite the efforts by manufacturers to minimize errors due to skin tone differences in modern sensors. The wearable device never receives calibration in a laboratory setting.

Simple Habits That Make My Data More Reliable

Here are some simple techniques that will be useful to you without any additional gadgets:

Give preference to trends over daily fluctuations – An occasional spike is not important, but it is a different story when the values and trends are elevated for two weeks.
Add your own notes – Log information about the performance level of your training (on a scale from 1 to 10), energy level or actual sleeping and waking hours, what factors affected them, traveling, etc. The application calculates new baselines based on this information.
Combine sources – Utilize the phone GPS for walking outside, while the cheapest chest strap will measure heart rate for intense workouts. Multiple sensors' data is automatically combined by many health applications.
Perform quick reality checks – Twice a year, cross-check readings against your chest strap at least once in the context of exercise or create a manual sleeping schedule for several days.
Use the right gadget for the purpose you want to solve – Oura ring is perfect for monitoring sleep and recovery, whereas Garmin or Apple watches are better for training and tracking your distance.

The Bottom Line: Smart Use Beats Perfect Hardware

None of these consumer wearables qualify as medical devices, nor will their next-gen versions be any different. The accuracy of heart rate measurements while awake, step count, general sleep tendencies and overnight HRV values can be relied upon. Calorie expenditure and sleep stage detection can be useful but still fall into a "helpful indicator" category, not perfect measurements.

If you use the data in tandem with how you actually feel, that would be the real gold mine. The use of consumer wearables has been highly motivational for me. For example, my Ultrahuman Ring has helped me realize my late-night snacking habits were affecting my heart rate drop during sleep, something which I previously did not pay much heed to.

Do you think some of the metrics in your wearable are more or less accurate than others? What kind of wearable do you have and what makes you believe its information? Let me know in the comments below.

Why Wearable Data Doesn’t Match Reality (And What to Do About It)

Shradha Puri — Tue, 14 Apr 2026 08:09:42 +0000

You put on your smartwatch. You kill your workout and check the results: 12,800 steps walked, 490 calories torched, a great score on sleep, nice heart rate zones. It all sounds accurate. Invigorating, even. Except it’s not. Not really.

Having spent many years with various health tech products that integrate with the likes of Apple Watch, Garmin, Fitbit, WHOOP and Oura, I have noticed an exact same pattern over and over again. Everything appears so clear and clean on the dashboard, but it doesn't always match what was going on in real life. Misleading insights are shared by coaches and bad apps get shipped.

And it’s not just some sporadic noise in the system, it’s an inherent problem every wearable product developer needs to know about. In today’s article, I will talk about why wearable data is often off and what you developers can do about it.

The Promise vs. The Reality: Hard Numbers from Studies

Wearables are sold as precision health tools, but independent validation tells a more sobering story:

Heart rate accuracy: Optical PPG sensors perform reasonably at rest (often within ±3-5 bpm), but errors increase significantly during intense or high-motion activities. Active heart rate accuracy ranges from around 67-86% depending on the device, with Apple Watch generally leading at ~86% and others like Garmin and Fitbit lower during dynamic movement. Dark skin types tend to have more inaccuracies due to the absorption of the light-green light used in most sensors by the melanin in their skin.
Step count: Moderate accuracy at about 68-82% overall. They generally underestimate by about 8-12% overall in free-living conditions and higher in non-ambulatory movements such as cycling, stair climbing, and load carriage. Garmin usually performs slightly better under controlled conditions, with the opposite occurring otherwise.
Energy expenditure: Energy expenditure is the least accurate among all metrics. Inaccuracies in energy expenditure often exceed 25-28%, with an accuracy rate of around 56-71%. The Apple Watch seems to have a higher accuracy rate for heart rate at 86.31% and 71.02% for energy expenditure. While Garmin is most accurate for tracking step count at an 82.58% accuracy. Estimates are based on indirect equations that use heart rate, movement data, age, weight and model-based formulas.
Sleep metrics: Devices seem to perform quite well when it comes to detecting sleep vs. wake state, as sensitivities are often greater than 90%. They, however, overestimate sleep time and efficiency, especially efficiency. Accuracy when classifying sleep stages is moderate, varying widely by device, with the Oura Ring being recommended over wrist devices.

Such biases are not uncommon, one-off incidents but rather systematic issues that impact millions of individuals everyday. When you design applications for fitness training, workplace health programs, insurance underwriting, or medical research, your designs stand on much shakier ground than you realize.

Why Wearable Data Diverges from Reality

This discrepancy arises due to various factors:

1. Technical Limitations
First of all, consumer wearables typically mount onto your wrist. They use 3D accelerometers along with optical heart rate sensors. The latter type is highly vulnerable to motion artifacts. Sweat, improper wear, tattoos, hair, skin color discrepancies and even applying lotion affects sensor accuracy. Any intense movement causes displacement of the watch against your skin.

2. Algorithm Assumptions
The algorithm is trained using population data. However, your unique physiological features (VO2 max, muscle fiber ratio, basal metabolic rate, medications, etc.) heavily impact "true" values. Unless you provide and continuously update these metrics, there’s no reliable means of compensation for the device.

3. Inherent Biases
A series of academic papers has discussed reduced accuracy for individuals with darker skin tone, larger wrists and peculiar body compositions. This problem doesn't come from the software implementation but from historical biases in training sets.

4. Lack of Continuous Calibration
In a lab, researchers use ECG chest straps and metabolic carts for validation. On your wrist during daily life? The device is making educated guesses with no continuous calibration against medical-grade equipment. It’s flying somewhat blind.

5. Data Pipeline Issues
Even when the hardware captures something useful, the way data is sampled, aggregated, filtered and synced to the cloud introduces further gaps and delays.

My Personal Reality Check

Since I have been tracking my data for years, I now know that one must be skeptical about these figures. There were days when I had supposedly slept really well, according to my smartwatch, but I felt sleepy and realized that I had several moments where I woke up throughout the night. Or days when my smartwatch displayed amazing calories burned, even though I only had a relatively light gym session.

What this has taught me is that one must be able to think differently regarding the data coming from the device. Your feelings, performance and personal perception will always come first. It would not do well to blindly trust everything shown by your wearable because it might make you overwork yourself or ignore your bodily needs.

Practical Ways Regular Users Can Bridge the Gap

It doesn’t require any technical knowledge to boost the accuracy of your results. Here are some techniques that have proved to be most effective for myself and many others:

Cross-Check and Manually Adjust

Periodically compare your device’s measurements with your real-life perceptions. If you notice something suspicious about your sleep score, add notes to the application and make manual corrections whenever you can. This will help you find patterns over time.

Add Your Own Context

Almost all popular apps offer the ability to enter additional data. For example, the type of workout, Rate of Perceived Exertion, current mood, nutrition or sickness. Use those functions. They can provide much more accurate calculations for your personal situation.

Combine Multiple Sources

Avoid trusting only wrist measurements. You can use GPS tracking on your smartphone for outside jogging or walking to get a more precise number of steps and covered distance. And in cases of workouts while training for a marathon, you may want to employ a heart rate monitor for periodic checking. Most of the applications gather information from various sources.

Look for Transparency

Use devices and applications that have confidence measures and ranges if possible ("calories ±20%", for instance). Study the limitations mentioned by the producers themselves in the documentation. Once you know your weak sides, the information will be much more valuable.

Periodic Reality Checks

Do a simple verification day every few months when comparing your watch with more precise devices, such as a chest strap while doing sports or logging all the details about your sleep manually. Take the discrepancies into account when analyzing your data and decide how much to trust it.

Focus on Trends, Not Single Days

One inaccurate reading on a certain day does not mean your wearable data is useless. Analyze long-term trends to get a bigger picture.

Choose the Right Tool for Your Needs

If you want some more encouragement to work harder towards your goal, just use any wrist device. In case of a more serious approach to your sleep and recovery or training, smart rings like Oura and chest straps will help.

The Road Ahead

Although newer models of wearables are getting better with more advanced sensors and software, there are still limitations. A perfect degree of wrist-based precision under all circumstances is still impossible.
What matters most is not perfection but proper use. The perfect combination would be the fusion of the quantitative data and the qualitative knowledge of your own body.

Wrap Up

The data obtained from wearables is extremely useful. However, it will only be so when we drop our expectation that it will be perfect. Treat it as one helpful voice in the conversation about your health, not the only voice you rely on. Always pay attention to what your body tells you first, then utilize the device to supplement information received from it.

More things that can help get the most out of your wearable data are eliminating what are clearly inconsistencies, manual entries to add what’s happening in your surroundings and tracking your trends.

The most successful people aren’t necessarily those with the latest high-tech devices. The most successful ones know their limitations and make the data work for them and not the other way around.