Study Finds Apple, Samsung, Garmin and Fitbit Smartwatches Miscalculate Exercise Calories

The study's central finding is that smartwatch calorie estimates can be off by 100% or more, according to Android Authority's coverage of a report by The Conversation. The inaccuracies were not limited to one brand; the study examined models from four major wearable makers. The higher a person's body fat percentage, the less accurate the smartwatch's calorie estimates may be.

Researchers recommend that users treat smartwatch calorie counts as rough estimates rather than precise measurements, especially if they rely on those numbers to manage their weight. That guidance applies to workout sessions in which the watch produces a calorie total after exercise.

Smartwatches have become common for health and fitness tracking and for convenience. Many users check the calorie figure after a strenuous workout, and that number can carry weight for those trying to stay in a calorie deficit. The new report indicates that such figures may overcredit the workout.

Android Authority's article notes that previous reports about inaccuracies have already led some users to interpret smartwatch numbers with caution. Even so, the habit of checking calorie totals after every workout remains common. The report suggests that users may need to change how much trust they place in those readings.

The report does not specify which exact models were tested or the full methodology behind the study. It also does not provide brand-by-brand error rates. What it does state is that the errors can be substantial and that body fat percentage is a factor in how far off the estimates may be.

The findings add to questions about the precision of consumer wearable health metrics. For users whose weight management depends on calorie accounting, the practical effect is that a watch's calorie count should not be treated as a definitive measure of energy expended during exercise.