In the same way runners call their GPS watches “Garmins,” so has “Fitbit” become synonymous with fitness trackers. The brand got its start in 2007 and has since dominated the category, expanding from the most basic of clip-on step counters to wrist-based smartwatches that can pay for your Starbucks latte, track its calories, and take an ECG while you sip on it. That said, not every runner wants all those features. (Or, maybe you want that and more, with built-in GPS to boot.) Either way, we’ve broken down Fitbit’s current most popular models, with in-depth descriptions and our detailed testing notes on their features to help you decide which one earns the spot on your wrist.
Fitbit Feature Cheat Sheet
Not every Fitbit offers all of the features listed below. Some functions are more premium, reserved for higher-end models like the Sense, while others are fairly standard across nearly every device the brand offers. We’ve broken down several features and terms you’re likely to see while shopping for a tracker, from the most common and straightforward functionalities to the lesser-known and sometimes confusing alphabet-soup acronyms. Bookmark this page and refer to this as you need to decide which are most important for you to have in your tracker.
Heart Rate Variability (HRV) monitoring: HRV is the variation in the amount of time between each heartbeat, measured in milliseconds. Tracking HRV can clue you into your body’s signs of stress, illness, and fatigue. High HVR is generally considered an indicator of a healthy heart.
ECG (Electrocardiogram) App: Place your thumb and forefinger on opposite corners of the Sense’s screen to perform a 30-second ECG and generate a report to share with your doctor. Your result will indicate Normal Sinus Rhythm, Atrial Fibrillation, or Inconclusive.
EDA (Electrodermal Activity) App: A two-minute scan measures your body’s response to stress by sensing changes in skin temperature and sweat gland activity. Complete a session by placing your entire palm on the device’s screen.
Breathing Rate monitoring: Simply put, this feature tracks respiration rate—the number of breaths you take per minute—while you sleep.
Stress Management Score: Your Fitbit calculates a rating between 1 and 100 to help you understand how well your body is handling physiological strain day-to-day. This score is based on your heart rate, HRV, EDA, sleep patterns, and physical activity, with a higher score indicating lower stress levels.
Cardio Fitness Score: An estimate of your VO2 Max, the maximum amount of oxygen you can utilize during intense exercise. Your Fitbit calculates a range based on your resting heart rate and info from your user profile; you’ll get a more accurate score by connecting your Fitbit to GPS for a 10-minute run.
Oxygen Saturation (SpO2) monitoring: While you sleep, your Fitbit can measure and track SpO2, the level of oxygen in your blood. A normal reading is typically between 95 and 100 percent but can vary based on age, respiratory health, and other physiological conditions. Monitoring SpO2 can provide insight to possible breathing issues, like sleep apnea.
Active Zone Minutes (AZM): Calculated using your age, resting heart rate, and time spent in different heart rate zones, AZM give you a better idea of how much and how vigorously you get moving each day. (For example, one minute in lower HR zones counts as one AZM, while one minute of high HR activity earns you double.) Based on the American Heart Association’s guidelines, the default AZM goal is 150 minutes per week, but you can adjust yours according to your own goals.
Fitbit Premium Membership: This more advanced version of Fitbit’s free app gives you deeper insight to your health metrics. We recommend getting it to utilize the most of your Fitbit’s features and receive more actionable recommendations for improving the health stats you’re tracking. In our testing, we found the Premium membership helped us make more sense of the data we collected, regardless of which tracker we used.
Voice Assistant: Allows you to control your Fitbit with spoken commands using Google Assistant or Amazon Alexa. You can say phrases like, “Set alarm” or “Start workout,” and even control other connected smart devices remotely.
SmartTrack: Automatically recognizes your type of workout and tracks relevant data and stats for that activity. For example, it can identify when you’ve started an outdoor run and will keep tabs on your pace and distance if you ever forget to hit start.
Sleep Score: Wear your Fitbit while you snooze to get a nightly evaluation of your sleep quality on a scale of 1 to 100. You can review your time spent in three different sleep stages (light, deep, and REM) and set the SmartWake alarm for your lightest sleep period to wake up feeling more refreshed.
Fitbit Pay: Store any credit or debit card on your Fitbit tracker and use it to make contactless payments purchases. Simply hold your device within range of compatible scanners at check-out.
Guided Meditation: In this guided breathing widget, you inhale and exhale along with light wrist-based pulses as an on-screen glowing circle waxes and wanes. One tester found it helped her consistently commit to mini two-minute sessions when establishing a new daily meditation practice.
How We Tested and Selected
Our team of test editors and Runner’s World staff have used nearly every Fitbit on this list both on and off the run. In addition to evaluating each tracker’s battery life, durability, price, and ease of use, we’ve paid special attention to the reliability and accuracy of their tracking abilities. We’ve worn these devices to confirm our pace and mileage on long runs, count our nightly hours in REM sleep, read our heart rates mid-workout, check our daily SpO2 levels, pay for a post-run slushie at the gas station, and even take an ECG. For the two models we haven’t personally tested (the Luxe and the Ace), we relied on our own knowledge of and experience with fitness trackers and smartwatches and consulted Fitbit’s product designers. We also surveyed online customer reviews, as well as professional reviews from trusted publications like Wired, Ars Technica, and PC Magazine.
—MOST COMPREHENSIVE HEALTH TRACKING—
Battery Life: 6 days
The Sense is the most advanced Fitbit to date and the closest current competitor to the Apple Watch, offering more health-monitoring capabilities—like the wrist-based EDA scan and ECG apps—than any other model in the Fitbit family. This powerful smartwatch is best for tech-savvy runners who already know their way around a basic tracker; it’s jam-packed with more than a half-dozen sensors to track pretty much anything and everything, so you’ll have to spend some time getting acquainted with the slew of features. During our testing, we found its around-the-clock heart-rate tracking and on-board GPS were nearly pinpoint precise, but we weren’t super thrilled with the watch’s sleep-tracking accuracy. The Sense thought one marathon-running tester, who had conditioned to a low resting heart rate, was snoozing in a light sleep stage when she was really just unwinding at the end of the day in bed with a book.
The Sense also has an SpO2 monitor and allows you to use your voice to control it—via Google Assistant or Amazon Alexa. (Devices like the Apple Watch and Samsung Galaxy Watch have this same tracking ability, but at higher prices and with shorter battery life.) That may not sound very exciting, but it’s a lot easier to just tell your watch what to do (like play music) than to hunt through menus while you’re running. The sleek square-oval design affords plenty of real estate to read splits on the run, though we found the display doesn’t always light up when we raised our wrist, and the touchscreen is somewhat unresponsive to exceptionally sweaty fingers.
Fitbit Versa 3
Battery Life: 6 Days
Fitbit’s most popular model finally adds what runners were craving: on-board GPS. With the addition of this new feature, the Versa 3 moves into first place as our top pick for runners. Now, the Versa delivers almost all of the same features as the new Sense—including the same display size and design—at around $70 cheaper. The 24/7 health- and activity-tracking features between the two models are identical (both offering over 20 workout modes and the ability to calculate your Cardio Fitness Score), as are the smartwatch functionalities, like Spotify streaming and Voice Assistant controls. The biggest differences between the latest Versa and the Sense are the watches’ cases—an aluminum build versus a more durable stainless-steel construction, respectively—and more nitty-gritty health-tracking sensors. The Versa doesn’t offer built-in ECG and EDA scan apps or wrist-based skin temperature monitoring; if those features are essential to you, go with the Sense. Otherwise, the Versa will likely meet your needs and save you some cash.
During testing, we liked how Versa’s interface was intuitive and easy-to-use—a good thing, considering you mostly navigate the watch’s settings and functions by swiping. The only physical “button” is an small indent on the left side of the watch that you use to return to the home screen. One gripe we had is that, as righties, we wore the watch on our left wrist and would sometimes hit that shortcut when we bent our wrist backward, accidentally starting the workout tracking. (However, we did like that the indented side button let us start and stop runs with a little squeeze, so we didn’t have to fiddle with a touchscreen while running.)
—BEST FOR STRESS MANAGEMENT—
Battery Life: 5 Days
GPS: Via mobile app
We’ve yet to fully test Fitbit’s newest option, the Luxe, but here’s what we can tell you about how it stacks up to the brand’s other offerings. The Luxe adds more in-depth stress-measuring capabilities to the usual all-day activity-tracking features and keeps it on the down low with its sleek bracelet-style. (In fact, Fitbit altered the metal injection molding process to make the stainless-steel frame look more like a handcrafted piece of jewelry.) The Luxe offers Fitbit’s newest Stress Management Score, and, when it’s paired with the Fitbit app, you can take more actions to improve your daily readings, like following the wrist-based guided breathing sessions and mindfulness practices. You’ll have to get used to tapping the screen to start and stop workouts, as the Luxe doesn’t have any physical buttons. But its SmartTrack feature promises to catch any sweat sessions automatically and categorize it into one of the 20 workout modes.
Keeping tabs on both physical and mental stress can be a huge boon to your training, so that’s why we’re especially excited about the Luxe. Its ability to provide insight to your HRV (a major key in determining your body’s ability to recharge and recuperate) combined with its stress- and sleep-monitoring features (including Sleep Score) help make prioritizing recovery a little easier and less expensive for busy runners—not to mention better-looking.
—BEST FOR KIDS—
Fitbit Ace 3
Battery Life: 8 Days
GPS: Not available
For kids six years and older, the Ace is a fun and easy-to-use entry point for health-tracking. (Some might argue that it’s not necessary, but we think it can be a cool way to get kids on the move—and even make tracking a family activity fun—while ensuring parents still hold the reins in controlling the band’s functionality.) Parents can set both kid and parent views in the Fitbit app, so kids can focus solely on earning and admiring their fitness badges, stats, achievements, and fun animated clock faces. Parents can then review kids’ daily activity time, and set bedtime/wake-up alarms and movement reminders. Plus, the longer battery life and waterproof silicone band means children can wear the Ace night and day, in the bath, or to the pool.
We especially like that the Ace’s sleep-tracking features can help kids create healthier sleep habits, an essential part of development. But it’s also fun; celebration messages come up when they hit their daily goals and big milestones, and the Ace can interact with other Aces to compete for virtual trophies and send messages of encouragement.
—BEST FOR FIRST-TIME TRACKERS—
Fitbit Inspire 2
Battery Life: 10 Days
We like the Inspire as a watch for those curious about wearing a fitness tracker but not quite sure yet if it’s for them. Or, maybe you wear your running watch 24/7 anyway, and wonder if there’s something more it could be doing for you off-the-run rather than just taking up space on your wrist. The second version of the Inspire lets you sample the best of Fitbit’s core features—like Sleep Score, all-day heart rate and activity tracking, and smartphone notifications—plus an on-board GPS to grab your pace and running mileage without your phone in tow. However, we did find that the connectivity could get a little spotty when running around tall buildings in the city. And, though Fitbit pegs the battery life at 10 days, we consistently ran out of juice in about a week, with GPS usage draining it the most.
If you’re seeking coaching insights to make your workouts more effective, the Inspire 2’s AZM and Intensity Map can help you dial in your efforts while you’re exercising and then provide feedback afterward. A series of vibrations alerted us when our heart rates climbed to cardio and peak zones or dropped below fat-burn territory, so we consistently knew when to push the gas and when to pull back during workouts. Post-run, we pulled up the Fitbit app to analyze how our pace and heart rate changed along a route map, giving us an excellent visual of where to improve. Given the Inspire’s modest screen size, the small type may be hard to read for some folks, including us when we glanced at our stats mid-run.
—AFFORDABLE BUILT-IN GPS ON A BUDGET—
Fitbit Charge 4
Battery Life: 7 Days
Now in its fourth version, the Charge has the longest lineage of any tracker in Fitbit's current lineup. The new generation still logs all the 24-hour activity- and sleep-tracking features previous iterations of the watch were known for but adds two of users’ most requested favorites: AZM and Sleep Score. It has a few other perks to make it feel more like a smartwatch, such as Fitbit Pay and Spotify control, so you can skip songs and scroll through your playlists from your wrist. As runners, we most appreciated the new built-in GPS—a notable upgrade for a $130 tracker—which we found surprisingly accurate in our testing. You won’t confuse it with a high-powered running watch, but if all you want to do is get reliable pace readings while out on your run, the Charge delivers. Bear in mind: The battery is touted to last up to a week, but GPS will drain it in just a few hours, so it’s not ideal as a primary activity tracker for dedicated cyclists or ultrarunners.
One tester who tried both the Inspire 2 and Charge 4 said she preferred the Charge’s more reliable GPS and noted that runners seeking the simplicity of an entry-level fitness tracker will benefit from dropping an extra $30 for this model if they can swing it. We also found that the Charge 4’s slightly larger touchscreen felt more responsive to inputs with sweaty hands, though its greyscale OLED screen didn’t get bright enough in direct sun. You may need to squint or find a shady spot before you can navigate the tracker.
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