The world's most in-depth and scientific reviews of outdoor gear

How We Tested GPS Sports Watches

By Larin McPeak ⋅ Review Editor
Thursday March 28, 2019
Lead test editor Jediah Porter putting devices (and his cardiopulmonary system…) through the paces on an uphill interval session.
Lead test editor Jediah Porter putting devices (and his cardiopulmonary system…) through the paces on an uphill interval session.

To see how these products tracked our athletes' movements, we covered some ground. We logged thousands of miles, mainly on foot but also while biking and swimming. Whether our feet were in running shoes, mountaineering boots, or backcountry ski gear, our testing was real-world and comparative. We would regularly wear and compare multiple watches on the same endeavor, but we also wore each one alone to focus our full attention on it.

Our team of diverse testers captured different perspectives on what makes an outstanding GPS watch. Our lead tester logged fifteen to twenty training hours a week and monitored virtually every one of her training and active hours with one or more of the products in this review. She snowshoed in the Austrian Alps after heavy snows trapped her in a mountain village. When she returned to Germany, she continued her Ironman training, running and cycling by castles, Renaissance churches, and 500-year-old Fachwerk houses.

After this much use, we experts on these watches and are excited to share the details with you.

Ease of Use


By simply using the devices, and sharing them with a broad and deep test team, we developed and distilled a significant body of user experience. We back up our opinions with years of experience and months of testing.

Garmin Fenix 5x Plus Sapphire and its many features
Garmin Fenix 5x Plus Sapphire and its many features

Features


We compared each product to a list of potential features. This list combines features included in each watch's hardware, software and user platforms on your pc or app. Some devices can be customized further. The list of potential features we compared are timekeeping, GPS distance and speed, GPS data recording, GPS navigation, step count, sleep tracking, built-in heart rate, compatibility with external sensors, dynamics, metrics, barometer, altimeter, thermometer, and smartwatch functions. We also considered the online and app platforms offered by each company since we can't judge the watches without considering their platforms.

Accuracy


To evaluate accuracy, we had to repeat a lot of our test runs over and over again. We ran for weeks and weeks, repeating routes and running new routes, all while wearing one watch on each wrist and carrying one watch in each pocket. In this way, we were able to test the GPS accuracy of up to 4 watches simultaneously. We could also test the optical heart rate monitor of 2 watches at a time, wearing one on each wrist. We never placed more than one watch on each wrist and one watch in each pocket to keep the GPS antennas from interfering with each other.

We also tried to run over bridges and next to bodies of water as much as possible to see if the watches mapped us as swimming instead of running. Afterward the run, we compared the distances, elevations, and mapping data, all while considering the limitations and features of each watch (e.g., does it have a barometric altimeter, etc.).

We found that a snug fit is imperative to get an accurate heart rate reading. The watches that didn't fit our testers as well usually reported skewed heart rate results. We also used a chest strap heart rate monitor while using one or more of the watches as a stable comparison control. Chest heart rate monitors are considered more accurate and are not affected by a watch's fit on the wrist. We also used the watches to monitor our sleep so we could review our resting heart rates. Since we were lying still and not sweating, sleep testing offered a more controlled environment for heart rate measurement testing.

Ease of Set-up


To measure Ease of Set-up, we noted how many steps were required, how clear the instructions are (including those on the device, in its app, or its paper manual), and the active and passive (i.e., synching) time required.

Battery Life


A number of variables make it challenging to test the battery life of these GPS watches fairly. Battery life hinges on how you use these watches. There are two use types that are important for athletes — normal use and activity usage. We tested normal use to find out how many days each watch stays charged when we run only a few hours a week and use it as a daily smartwatch, which included fielding random numbers of text notifications a day.

We tested activity use to determine how many hours each watch can last during a nonstop activity, like a race. To do this, we let each watch run tracking data from a full charge until it was empty to see which watch would make your 100-mile ultra without needing a charge, and which wouldn't. An ultra runner, cyclist or triathlete might need the battery to last during their activity for 10+ hours.

Auf Wiedersehen! That is the end of our GPS Watch review. Time to run.
Auf Wiedersehen! That is the end of our GPS Watch review. Time to run.

Design


Design is mainly a function of size, fit and the somewhat subjective factor of appearance. Larger watches will not fit all wrists. Smaller ones may fit all wrists, but they make it difficult to read the screen. We measured and weighed each one, and noted whether they are difficult to wear under typical running and athletic clothing and if size affected the fit, and thus the accuracy of the optical heart rate monitor.