A peer-reviewed meta-analysis published recently provides potential answers for Apple Watch users who have questioned the accuracy of their Activity Ring data.
Apple Watches tend to have some of the best heart rate tracking among wearables. | Image by PhoneArena
Let's start with the good news first. According to the findings, Apple Watches are highly accurate when it comes to tracking heart rate and counting steps. This is in line with our own experience with Apple Watches, including during our Apple Watch Series 10 review (Apple's latest smartwatch).
The mean absolute percent error (MAPE) for these metrics in the meta-analysis was just 4.43% for heart rate and 8.17% for step count — both well below the 10% threshold typically used to define excellent performance in consumer wearables.
The researchers also noted that newer Apple Watch models performed better across the board. While the study doesn't specify model-by-model results, doctoral student Ju-Pil Choe (one of the study authors) says:
While we cannot say every update is a big leap forward, there is a noticeable trend of gradual improvements over time. It shows that Apple is refining the technology over time.
Calories burned is still a weak spot
Smartwatches are still not that great at tracking calories, but that doesn't mean you can't use them for motivation. | Image by PhoneArena
But not all metrics scored so well. The study found that estimates of energy expenditure — aka how many calories you burn — were far less reliable. The average error rate here jumped to 27.96%, with inaccuracies present across various activities, including walking, running, cycling, and high-intensity workouts.
That puts Apple Watch roughly on par with other wearables, like the Fitbit Surge, which also struggles with calorie estimates. This shouldn't come as a surprise, though, as it is an extremely difficult task to measure calories burned. There are all kinds of things to factor in like body weight, movement type, metabolic efficiency, and even skin tone.
Smartwatches often rely on general algorithms that combine heart rate data, sensor input, and user profile info to estimate calorie burn. But that process leaves plenty of room for error. Other studies have found that calorie estimates on wearables can be off by as much as 40% to 80%, depending on the device and activity.
Recommended Stories
The bottom line
Use the Apple Watch — or any smartwatch, for that matter — as a guide, not gospel.
The University of Mississippi study provides a helpful reality check: Apple Watches are excellent at tracking heart rate and step count but should not be relied on for precise calorie measurements.
Personally, I find a smartwatch most valuable as a way to log workouts and monitor consistency. There’s something genuinely motivating about seeing your progress visualized, whether it’s a graph of completed runs or a streak of active days.
That said, I’ve also left my watch behind on occasion, and there’s a certain freedom in it. Without the pressure of stats or metrics, you start to tune into how your body feels in the moment — and sometimes, that’s exactly the kind of workout you need.
Aleksandar is a tech enthusiast with a broad range of interests, from smartphones to space exploration. His curiosity extends to hands-on DIY experiments with his gadgets, and he enjoys switching between different brands to experience the latest innovations. Prior to joining PhoneArena, Aleksandar worked on the Google Art Project, digitizing valuable artworks and gaining diverse perspectives on technology. When he's not immersed in tech, Aleksandar is an outdoorsman who enjoys mountain hikes, wildlife photography, and nature conservation. His interests also extend to martial arts, running, and snowboarding, reflecting his dynamic approach to life and technology.
A discussion is a place, where people can voice their opinion, no matter if it
is positive, neutral or negative. However, when posting, one must stay true to the topic, and not just share some
random thoughts, which are not directly related to the matter.
Things that are NOT allowed:
Off-topic talk - you must stick to the subject of discussion
Offensive, hate speech - if you want to say something, say it politely
Spam/Advertisements - these posts are deleted
Multiple accounts - one person can have only one account
Impersonations and offensive nicknames - these accounts get banned
Moderation is done by humans. We try to be as objective as possible and moderate with zero bias. If you think a
post should be moderated - please, report it.
Have a question about the rules or why you have been moderated/limited/banned? Please,
contact us.
FCC OKs Cingular\'s purchase of AT&T Wireless
Things that are NOT allowed: