How FitBit Works

Just clip it on and go. The FitBit tracks much of your physical activity and integrates with software that encourages you to be more and more active.
Courtesy FitBit

When it comes to motivating people to work out, Richard Simmons has nothing on FitBit. FitBit is a physical activity tracker designed to help you become more active, eat a more well-rounded diet, sleep better and ultimately, turn you into a healthier human being. And it does it all without subjecting you to Simmons or his maniacal grin.

The FitBit was introduced in 2008 by co-founders Eric Friedman and James Park in San Francisco. In short, it's a 21st-century pedometer.


The equipment is deceptively simple. About the size of a clothes pin, the FitBit is shaped like a clip, which you can easily slide into your pants pocket or onto a bra strap, as it's only around 2 inches (5 centimeters) long and about half an inch (1.2 centimeters) thick. Throughout the day, FitBit logs a range of data about your activities, including the number of steps you take, distance traversed and calories burned. It's also sensitive enough to detect just how vigorous your motions are, which differentiates a slow stroll from a jog that consumes far more calories.

At night, you slip the FitBit into a wristband so it can monitor your sleep quality. It knows when you go to bed, how frequently you awaken and how long you lie prostrate, staring at the ceiling, pondering unmet deadlines. Thrashing around at midnight because of that quadruple latte you gulped at 4 p.m.? FitBit will know.

The clip has a built-in OLED (organic light-emitting diode) that scrolls current activity data. So if it's late in the day and you still have 8,000 steps to get to your goal of 15,000, you know it's time to get going, and fast. A little flower avatar "grows" as you become active; it gets shorter if laziness takes hold.

Every time you pass within 15 feet (4.5 meters) of its wireless base station, FitBit automatically offloads a cornucopia of numbers. From there, your statistics go to your online profile, where you can peruse details, monitor your progress (or lack thereof) and redouble your dedication to getting into shape.


Get Your Bits Fit

It’s so small that you can wear it just about anywhere, which means you’ll have no excuses for not staying active. Unless, of course, you lose it.
Courtesy FitBit

FitBit is evolving, from both a hardware and software perspective. In October 2011, the clip itself was upgraded and renamed the FitBit Ultra.

The Ultra has the same features as the original FitBit, with one major addition: an altimeter. With the altimeter, Ultra knows how much elevation you lose or gain throughout a day. That's valuable information because inclines are hard work. For example, if you climb the stairs in an 80-story building, you'll burn more calories than if you'd gone the same distance on a flat sidewalk outside.


In addition, the Ultra lets you check the time and includes a stopwatch so that you can manually time various activities. It displays so-called "chatter" messages, too, that are supposed to encourage you to keep moving (even though that super-sized milkshake is causing you some serious side cramps.

And of course, there are the aesthetics. The original FitBit featured teal accents; the Ultra comes with your choice of either blue or plum.

There's enough internal memory that the FitBit can store an entire week's worth of continuous data. Battery life is estimated at about three days, and you can check power levels at any time by plugging the unit into its base station.

FitBit doesn't track every kind of activity. It's not waterproof, so swimming is out. It can't tell that you just lifted weights for an hour, or that a rigorous yoga class just wiped you out. To bridge the gap, you can manually log activities through your Web account. Alternately, you can use the FitBit smartphone app (for iPhone or Android) to record workouts, as well as your food intake. The app doesn't let you upload data from your FitBit to your account, though. Only your computer-connected base station allows you to do that.

Once your data is synced to your online account, you have a plethora of options. You can check your daily, weekly and monthly stats, of course, as well as set goals. And you can create and monitor a food plan that helps you make better eating choices.

As you achieve specific goals, you'll unlock virtual badges that reward your positive behavior. These tokens recognize your achievements and push you to aim for loftier goals. You can also compare your stats with those of approved friends. Create an online group of friends or co-workers and together, you can share wisdom and inspiration that'll keep you on track.

By default, older versions of FitBit made your workout information public. Because of the potential for embarrassment, the company changed that setting. Now, your information is private until you configure it otherwise.

Curious about the FitBit's technology? Take a peek on the next page.


The Tech Teardown

The base station charges your FitBit’s battery, and every time you pass within about 15 feet of it, the FitBit transfers more of your activity data.
Courtesy FitBit

So you clip a little plastic widget to your clothes every day, hoping that it'll somehow magically transport you out of couch potato land and into healthful bliss. The process seems straightforward, but the technology is sophisticated.

The linchpin of FitBit is its three-dimensional accelerometer system. In plain language, that just means it tracks motion, as well as the intensity of that motion.


Then FitBit's software relies on special algorithms to convert raw accelerometer data into usable information. Those algorithms are the secret sauce that the company has worked diligently to tweak and improve, by experimenting and comparing FitBit's accuracy with other test machines.

For example, as the engineers test the "calories burned" feature, they compare FitBit's results with a portable telemetric gas analysis system. The latter analyzes gas composition as you exhale and very accurately determines your calorie usage.

With a lot of trial-and-error, FitBit has learned how to track and convert your energy expenditures (tracked by the accelerometer) into information about the number of calories you burn. Likewise, the company's testers have developed algorithms that work well for tracking the steps you take and how far you've moved.

The sleep tracking feature is more rudimentary. It merely logs how often you move throughout the night. So, if you're reading in bed and not moving the arm to which the FitBit is attached, it will think you're sleeping. Likewise, if you tend to flail about often during the night, the device may interpret your motions as meaning you're not sleeping at all.

In order for all of this to work properly in a population that differs greatly in physical characteristics, FitBit needs more information. Using your Web-based account, you enter personal information regarding age, weight, height and sex. You can also click to log your meals so that FitBit knows how many bacon triple cheeseburgers you need to work off.

Armed with your personal stats and a continuous stream of motion data, FitBit will keep you updated with information that tells you how much -- or how little -- activity your body is getting.


Fitter, Bit by Bit

FitBit Ultra comes in two colors and is small enough to wear every day of the week
Courtesy FitBit

FitBit's healthy aims are a hit. FitBit's relatively affordable price and ease of use has won it a share of loyal users and some accolades. In 2009, FitBit was an Innovation honoree in the Health and Wellness category at the Consumer Electronics Show in Las Vegas.

But FitBit is only one product in a current trend of wearable fitness gadgets. It has plenty of competition. Jawbone's Up, for instance, is a wristband that tracks your movement and vibrates when you've been inactive for too long. It has a smartphone app and social networking features, too.


There are also more sophisticated (and more expensive) products for people who have both calories and cash to burn. The Basis Band is a watch-like device that comes loaded with sensors that track heart rate, movement and even galvanic skin response, which is a measurement of your stress levels.

The BodyMedia Fit is an armband equipped with four types of sensors that supposedly capture around 5,000 data points every minute. In addition to a motion sensor, it logs temperature, galvanic skin response and heat flux, which relates to the amount of heat that's dissipating from your body. Together, these sensors may provide a clearer picture of your overall activity and health.

And when it comes to monitoring sleep quality, it gets more complicated. Sleeping is highly variable and individualized behavior, and as such, there are many gadgets dedicated solely to tracking the quality of your rest. Those include the Lark sleep sensor, Zeo and others. If you really need sleep-related functions, you might be better off using something in this product category instead of a fitness gadget.

All of these products are tech-powered gadgets. In our Internet- and statistics-saturated age, devices like the FitBit really are a sign of the times. Will FitBit and its ilk help usher in a new era of health-consciousness? Or will they become obsolete and irrelevant in the face of our yearning to stuff ourselves with just one more sea-salt encrusted French fry?

Perhaps the social networking components of FitBit will propel it to greater success and help transform people into creatures who appreciate their physical fitness. Or maybe the gadgetry will just wind up on the car floor mats, wedged next to an empty fast food wrapper. Only time will tell, and when it does, you can bet that your fitness app will share it with the rest of your social network.


Author's Note

Up until a few years ago, my only exercise was short walks to and from the fridge.

Then, a persistent (read: incredibly annoying), running-obsessed friend finally convinced me to get outside and run, if only a few sluggish miles. She encouraged me to start slow, take my time and let my body adjust to new routines. The transformation was slow and not without struggle, but eventually, I got into the best shape of my life.


It was the consistent encouragement and goal tracking that helped me accomplish that feat. Gadgets like FitBit are kind of like having a friend who prods you along when you really don't feel up to worrying about your health. It keeps the issue front and center, every day, so that you learn to prioritize physical well-being. And as some people say, your health is all you have. If devices like these can give us better, longer lives, I'm all for them.

Related Articles


  • Biggs, John. "The FitBit Ultra: More FitBit Goodness, Same FitBit Package." Techcrunch. Oct. 3, 2011. (April 20, 2012)
  • Cheung, Jacqui. "How the FitBit Got Me to Walk More and be a Part of Society." Arstechnica. April 2012. (April 20, 2012)
  • DesMarais, Christina. "Behind the Basis Band's Pre-Launch Hype." Jan. 12, 2012. (April 20, 2012)
  • Dolan, Brian. "FitBit Data Heading to Your EHR Soon?" April 16, 2012. (April 20, 2012)
  • FitBit Company Blog. "A Brief Look into How the FitBit Algorithms Work." Feb. 26, 2009. (April 20, 2012)
  • International CES site. "2009 Innovation Honorees." (April 20, 2012)
  • Loftus, Jack. "Dear FitBit Users, Kudos on the 30 Minutes of Vigorous Sexual Activity Last Night."Gizmodo. July 3, 2011. (April 20, 2012)
  • Mason, Betsy. "Pocket-Sized Workout Pal is Data Geek's Dream." Oct. 16, 2009. (April 20, 2012)
  • Miller, Matthew. "FitBit Launches Android Apps for Activity Monitor and Food Planning." March 22, 2012. (April 20, 2012)
  • Morris, Clayton. "The FitBit Ultra, a High-Tech Weight Loss Winner." Fox News. April 2, 2012. (April 20, 2012)
  • Needleman, Rafe. "Basis Strong-Arms Other Wearable Body Sensors." CNET. July 28, 2011. (April 20, 2012)
  • Needleman, Rafe. "New FitBit Knows How High You Are." CNET. Oct. 3, 2011. (April 20, 2012)
  • Netburn, Deborah. "FitBit Shares Your Weight Loss Progress with the World." April 15, 2012. (April 20, 2012)
  • Richmond, Shane. "FitBit Ultra Review." The Telegraph. April 5, 2012. (April 20, 2012)


Frequently Answered Questions

Does Fitbit measure blood pressure?
No, Fitbit products do not measure blood pressure.