How to track HIIT on Fitbit Charge 4 – sleep tracking, price & review


What is new in Fitbit Charge 4?  How to track HIIT on Fitbit Charge 4 or sleep tracking? It has built-in GPS to see your pace and distance on screen during outdoor runs, rides, hikes and more and see a workout intensity map in the app that shows your heart rate changes along your route. Its slimmer form factor, longer battery life and lower price point (now on sale for $99) make it a great alternative for anyone looking to monitor their health and fitness, without the added bulk of a full-blown smartwatch. Get details in Fitbit Charge 4 review.

We independently review everything we recommend. When you buy through our links, we may earn a commission. Lean how we earn commission

Pros & cons – Fitbit Charge 4


  • Sleek, minimalistic design
  • Built-in GPS
  • Robust companion app
  • Fitbit Pay available on all models (not just Special Edition)
  • Motivating Active Zone Minutes metric
  • Heart rate zone notifications
  • Sleep tracking and analysis
  • Spotify support


  • Screen wake can be finicky
  • Basic interface
  • Low visibility in direct sunlight
  • No quick reply for messages on iPhone
  • Shorter battery life than the Fitbit Charge 3

Fitbit Charge 4 specs

  • Steps, heart rate and sleep tracking
  • GPS built in
  • Blood oxygen tracking
  • Seven-day battery life
  • Fitbit Pay
  • Notifications
  • Spotify controller
  • VO2 Max tracking
  • Workout tracking modes


The regular Charge 4 comes in three different colors with silicone sports bands, but the Special Edition, or SE, version that I tested out also comes with a woven band option for $20 more. Straps are easy to swap out (unlike the Versa 2, which has tricky toggles) and if you’re upgrading from the Charge 3 you’ll be able to use those bands on the newer tracker. There are also a bunch of third-party strap options available to customize your look. 

Fitbit Charge 4 best Price

The Fitbit Charge 4 is available on, as well as at online retailers including Amazon, Best Buy and Walmart. It’s available in black or rosewood (a deep purplish red) for $149; a special edition, with a woven black/granite reflective band, is available for $169. 

How to track HIIT on Fitbit Charge 4?

Step 1 : wear it tightly

Check that your Charge 4 isn’t getting loose or getting down on your wrist. You can also try wearing it higher when you’re doing a very intense activity. You may want to try higher than two fingers as shown on the image. 

How to track HIIT on Fitbit Charge 4
How to track HIIT on Fitbit Charge 4

The movement may prevent the sensor from finding an accurate heart rate. With high-intensity interval training, P90X, boxing, or other activities where your wrist is moving vigorously and non-rhythmically. Similarly, with exercises such as weight lifting or rowing, your wrist muscles may flex in such a way that the band tightens and loosens during exercise.

Try relaxing your wrist and staying still briefly (about 10 seconds), after which you should see an accurate heart rate reading. Note that your tracker will still provide accurate calorie burn readings during these types of exercise by analyzing your heart rate trends over the course of the workout.

Step 2: Set intervals

You can set custom intervals by doing the following:

  1. Tap Account icon > your device image from the Fitbit app dashboard,
  2. Choose Exercise Shortcuts.
  3. Select Interval Workout. 
  4. Set your intervals.
  5. Sync your device to save the changes.

Step 3: Long press of the button

 I recommend tracking your HIIT sessions by long  holding the button on your Fitbit Charge 4 until  you feel it vibrating; do the same when you finish your workout. Sync your tracker and check your Activities Log.

Try relaxing your wrist and staying still briefly (about 10 seconds), after which you should see an accurate heart rate reading. Note that your tracker will still provide accurate calorie burn readings during this type of exercise by analyzing your heart rate trends over the course of the workout. Hope this helps.

Customized exercises on your device

On select Fitbit devices, you can customize the exercise app to show only the workouts that interest you. Keep the treadmill exercise if you use it, and ditch swimming if you don’t. After you update the Exercise app Icon used for the Exercise app on many Fitbit smartwatches, which looks like an orange stick figure running on your device, you’re ready to work out! Don’t forget to start the exercise before you start sweating. For more information, see How do I track my activity with my Fitbit device?

HIIT on Fitbit Charge 4 – sleep tracking & review


The Charge 4 looks sleek, measuring less than half an inch at its thickest point. The largest part of the device is the 1-inch (measured diagonally) LED touchscreen. Despite its relatively low 100 x 160 pixel resolution, it’s simple to scroll through apps, peruse data, and manage settings with the swipe of your finger.


the Charge 4 features a grayscale touch screen that measures one inch diagonally. That said, the grayscale is getting a bit long in the tooth at this point,  especially compared with the bright, colorful display on the $25 Wyze Band.


 It has a monochrome OLED display that’s just big enough to show notifications and activity stats without feeling too cramped. Outdoor visibility is decent, and I never had any problems seeing it in direct sunlight.

Watch face

You can customize the tracker with different watch faces, depending on your mood or the look you’re going for that day. I selected the Mod Clock Date, which shows the current time, date, and your step count for the day. Other clock faces show additional metrics like your Active Zone Minutes and heart rate. 

Fitbit Charge 4 Activities review

The Charge 4 tracks over 20 different activities, from cycling to yoga. It’s also water resistant up to 50 meters like the Charge 3, so you can use it for swimming. You can program up to six exercise shortcuts on the Charge 4, but you do have to choose them and sync from the phone app. You can also set it to track your runs automatically, and set goals for things like pace, distance or calories burned before you start each activity. 

The Charge 4 tracks your steps, distance, floors climbed, calories burned, and Active Zone Minutes, a new metric earned for time spent in fat burn, cardio, or peak heart rate zone. Women can use the Fitbit app to track their periods and fertile windows, and view where they are in their cycle from their wrist. We also discussed earlier on how to track HIIT on Fitbit Charge 4.

Swiping option

 You can swipe up from the clock face to view fitness stats including your steps taken that day, hourly steps, Active Zone Minutes, current and resting heart rate, distance covered, calories burned, floors climbed, sleep data, your weight, water intake, and more. Swiping left from the clock face lets you access on-device apps, including Exercise, Spotify, Agenda, Relax, Timers, Alarms, Weather, and Settings. A swipe down on the clock face brings up your notifications.

Fitbit Charge 4 Sleep tracking benefits 

I’ve never gotten much out of tracking my sleep in the past. With a 6-month-old baby and a toddler waking me up at odd hours of the night I was scared to even see my stats the next morning, let alone get graded on my sleep. Each morning, the Fitbit app gives you a Sleep Score based on everything from sleep duration to sleep stages, heart rate and variations in blood oxygen levels (SPO2) and skin temperature. 

After a few nights of testing, it’s actually provided some useful data about my sleep habits (Fitbit Charge 4 Sleep tracking option). For starters, I’ve gotten a passing grade (above a 60) every single night, despite waking up to nurse my little one. The app told me it’s normal to spend up to 45 minutes awake each night, which was comforting. It also gives you advice on how to improve your score, like keeping your bedtime consistent, regardless of how late (or early) it is. 

The Fitbit app (Fitbit Charge 4 Sleep tracking) offers a wealth of information about your sleep. You can see graphs for each night showing the amount of time you spent asleep and awake, your sleep stages throughout the night, and how your sleeping heart rate fluctuated. These insights can be a good wakeup call if you’re not getting enough shut eye. 

Fitbit Charge 4 Sleep tracking

The app also shows an Estimated Oxygen Variation graph indicating changes in your breathing as you slept. The app notes that “blood oxygen saturation normally fluctuates, but high variations can be linked to breathing issues.” 

Pulse Oximeter

The Fitbit Charge 4 also has a pulse oximeter onboard, which sits right next to the heart rate sensor. The SpO2 sensor records your blood oxygen levels while you sleep and helps provide an estimated oxygen variation graph in the sleep section of the Fitbit app. High variations in your blood oxygen levels can be linked to serious issues like sleep apnea. If you see any outlying data in your chart, you may want to contact your doctor. However, Fitbit doesn’t have FDA certification for this sensor, so the Charge 4 can’t technically detect sleep apnea, though it can show you the important warning signs.

Fitbit Charge 4 Battery life review

Fitbit says the Charge 4’s battery lasts up to seven days, or up to five hours while using GPS. After wearing it for a full 24 hours (before testing GPS), the Charge 4 still had 85 percent battery, which is pretty good. Using GPS to track a workout depleted that number significantly faster, but that was expected.

To preserve battery life, you can enable a feature called Dynamic GPS that uses your phone’s GPS when you have it with you, and the Charge 4’s GPS when you don’t.

Fitbit app

Connecting the Charge 4 with the Fitbit app is simple. You open the app, select Set Up a Device, plug the tracker into its charger, and wait for a smiley face to appear on the screen to indicate it’s charging. From there, just follow the instructions in the app to pair it with your phone via Bluetooth and enable notifications. The app then begins setting up your Charge 4 and installing software updates if they’re available, which for me took more than an hour.

In the Exercise section of the Fitbit app, you can see a color-coded workout intensity map showing your route and your heart rate zone at any point. For my run/walk, the map showed that I reached cardio zone shortly after heading out, then alternated between fat burn, cardio, and peak zones for the rest of the time. Another color-coded map shows changes in your pace throughout the run. 

How to track HIIT on Fitbit Charge 4 or sleep tracking

The Charge 4 is the first Fitbit device with Active Zone Minutes, which measure how hard you worked during an activity based on your age and resting heart rate.

Fitbit Charge 4: Fitbit Pay

I’ll admit, I didn’t think much of contactless payment until I became slightly paranoid at touching any surface in public. However, it’s nice to know that I could use the Charge 4 to pay for stuff without having to put my fingers on a keypad. While not as ubiquitous as Apple Pay or Google Pay, Fitbit Pay works with 500 issuers, retailers in 44 countries, and 10 transit systems worldwide — not that I’m planning to use the New York City subway in the near future. 

The Charge 4 is the first of Fitbit’s fitness trackers to have this feature, but it is available on the Versa, Versa 2, and Ionic. Here is a list of participating banks for Fitbit Pay


The Fitbit Charge 4 charges through a USB cable that connects to the watch via a large clip. It’s easy to line up the connectors (it clamps securely around the whole body of the watch, making it much easier than the similar charging clips used by Garmin devices), and a full charge takes under an hour.

Editor’s recommendations

Lead Content Editor
Lead Content Editor

I enjoy creating stuff and giving back to my community. My days are spent producing content for brands who need an internet presence and for things that I adore. I bring with me six years of experience generating content and obtaining leads from untapped markets. I concentrate on the qualities and advantages of the goods that add value for my audience. After reading my reviews, anyone who want to purchase a product from me are given my honest and open recommendation. I integrate my reviews with those of actual people to make the content authentic and accurate. Please take a moment to contact me if you see any deviations; I always value and appreciate hearing from my readers.

Articles: 1412