comparison: the fitbit flex vs fitbit charge - which is the better choice?

Comparison: The Fitbit Flex vs Fitbit Charge

Fitbit has made a name for itself by selling wearable fitness trackers that can be bought at an affordable price. These wristbands will count the number of steps you take each day and monitor your sleep patterns each night, tracking the results so you can monitor your physical well-being with ease.

The device has been proven to be an unparalleled tool for people looking to achieve specific physical goals or for people who are simply looking for a general health improvement.

Fitbit has a whole line of trackers but the two most popular models are the Fitbit Flex and the slightly newer Fitbit Charge HR. Either product will help you to monitor the quality of your daily activities. However, there is a number of differences between the two devices.

In order to help you through this dilemma, both devices have been carefully studied and an in-depth review has been crafted that will compare important aspects such as available features, battery life, design, price, and more. With luck, the following will help to give you a better idea of the pros and cons of each model.

Key Features That Both Devices Share

Both the Flex and the Charge will report how active you are each day. They both:

  • Count the number of steps you take
  • Calculate the distance you have walked
  • Calculate the number of calories burned
  • Monitor your sleep patterns
  • Wake you up at an opportune moment in your sleep cycle with a vibrating alarm
  • Automatically sync with the Fitbit app on your smartphone and/or computer

What Does the Fitbit Charge Add Over the Flex?

fitbit charge

In addition to these functions, the Charge has a number of additional smartwatch features, or special fitness bells and whistles, that are not found in the older Flex.

  • Display of Results
    With Flex, you will need to use the app on a smartphone or computer to view the readouts. Yet with the Charge, you can observe your results throughout the day by simply looking at your wrist.
  • Caller ID
    The Charge has an additional caller ID function, allowing you to see who’s calling without taking out your phone. This was added to help spare people from undesired interruptions. You cannot, however, answer the phone with the wristband.
  • Inclines
    The Flex can count the number of stairs you climb but does not recognize inclined planes. Walking up a hill burns more calories than walking on level ground- the Charge takes this into account; the Flex does not.
  • Instant Sleep Results Display
    The Charge has an auto-sleep detection function that knows the second you wake up and instant displays a breakdown of how good your night’s sleep was. With Flex, you will have to wait as long as it takes to reach for your cell phone to see the results.

Head to Head – Core Features Evaluation


The display of the Flex is very basic and easily the most minimal of the fitness tracking devices. There is a slim screen with little LEDs that light up to mark how much overall progress you have made towards your day’s fitness goals. Each light represents 20% of your goal. For specific details, however, you must consult a computer or smartphone.

The Charge OLED display is a bit more technical. Its LCD screen can display the exact numbers of each category you are working on.

Moreover, it will inform you which areas need to be improved in order to reach your stated goals. This means it will let you know if you need to move around more or burn more calories, which can be very helpful for those who are concentrating on specific improvements.

Battery Life

The length of time a tech gadget can go between charges is often an important determining factor for many purchases and fitness trackers are no exception.

Both the Flex and the Charge have lithium polymer batteries that take an hour to completely charge and both use USB cables for charging. The Flex will remain charged for 5-7 days whereas the Charge can stay powered for 7-10 days.

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02/18/2024 03:19 am GMT

Water Resistance

Water-resistance is also a very important factor in deciding which Fitbit to buy. Most likely, you will be wearing the device while working out, which could potentially mean a lot of sweat.

Fortunately, both the Flex and the Charge are waterproof and can be submerged in up to 33 feet of water without short-circuiting. The Flex can remain underwater for a longer period of time because prolonged submersion messes with the Charge’s clock. Nonetheless, experts highly recommend that you take off any sort of fitness tracker before going snorkeling or scuba diving.

Neither the Charge nor the Flex can monitor swimming activity.

Both devices are resistant to minimal water contact such as perspiration, splashes, dishwashing, and showering. Yet Fitbit cautions that regular and/or prolonged water exposure could weaken the rubber wristband and potentially cause the device to start to smell bad.


The Flex wristband is made of a rubbery material and has a standard clasp. It comes in ten different colors. The Flex is slimmer and lighter than the Charge.

The wristband of the Charge is wider because it has a larger display screen. It also has a buckle-like clasp crafted purposefully to counter complaints that the clasp of the Flex sometimes comes undone. The band is also made of rubber and has a textured design. It comes in four different colors.

Both wristbands are flexible and durable. Importantly, neither the Flex nor the Charge causes the skin rash problem that resulted in a mass recall of the Fitbit Force. The Fitbit company had Harvard experts purposefully engineer a band that is highly resistant to skin irritation.

The company still advises Fitbit wearers of any model that sweating for more than two hours can cause some irritation and the device ought to be washed before wearing it again.


  • The Flex is thinner and lighter than the Charge. The Flex is 13.99mm wide and the Charge is 21.1mm wide. The Flex weighs 29 grams and the Charge weighs 30 grams.
  • In terms of wristband dimensions, the Flex comes in two sizes: small (5.5 – 6.9 inches) and large (6.3 – 8.2 inches).
  • The Charge comes in three sizes: small (5.5 – 6.7 inches), medium (6.3 – 7.9 inches), and large (7.8 – 9.1 inches).
  • The purchase of either device includes a wireless sync dongle and charger cable. Both the Flex and the Charge are compatible with Windows and Mac computer operating systems as well as both Android and Apple smartphones.


Last but not least, it is time to consider the price. This is usually the make or breaks factor for any purchasing decision.

Both fitness tracking devices are moderately priced. You can find cheaper knock-off brands online as well as more expensive trackers such as the Apple Watch. With Fitbit, you know you are buying a quality product with a well-established online platform.

The Charge is bigger and has more up-to-date features, plus it is newer. It currently sells for approximately $120. Meanwhile, Flex is an older model and cannot do as much as the Charge. It is currently selling at around $99.

Summary – Key Specs Comparison

Here’s a quick high-level look at the key distinctions between the two:

Features Fitbit Flex Fitbit Charge
Step Counting X X
Distance Calculating X X
Calorie Counting X X
Sleep Monitoring X X
Vibrating Alarm X X
Automatic Sync X X
Displays Results No X
Caller ID No X
Tracks Inclines No X
Instant Sleep Results Display No X
Display Type LED LCD
Battery Life 5-7 days 7-10 days
Water Resistance Up to 33 feet Up to 33 feet
Band Options Rubber, 10 colors Rubber, 4 colors
Width 13.99mm 21.1mm
Weight 29 grams 30 grams
Price Range $80-100 $100-130

Final Analysis – Fitbit Flex vs Charge?

fitbit flex watch

Both the Flex and the Charge are excellent fitness trackers. When it comes to deciding which is best, it really depends on what you are looking for in a health-monitoring device.

Who the Charge Is for?

For people who have serious goals in mind for which they are using the Fitbit as a tool to help them achieve, the Fitbit Charge HR is the way to go. It gives more in-depth, on-the-spot analysis meaning you can literally track your progress every step of the way.

Furthermore, the Caller ID function means you can check to see who is calling without interrupting your workouts and decide whether or not the call is worth answering.

Who the Flex Is for?

For people who are considering buying a Fitbit in hope of improving their general well-being, Flex would be a better choice. You can monitor your day’s physical activity with ease on your smartphone or computer. But the minimal nature of the Flex will allow you to track your activity without becoming obsessed with statistics.

Already, people are far too attached to their cellphones compulsively checking for emails or social media updates. The Flex saves you from having another gadget to obsess over. Plus it’s cheaper and more fashionable.

Both the Flex and the Charge have received number one ratings in consumer reviews thanks to their superiority in performance and style. Either device will help you improve your overall health, which is the most important thing. In the end, you really can’t go wrong buying either.

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02/18/2024 12:04 am GMT

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