How Does Fitbit Track Steps?

Turning your motion into data

Have you ever wondered how a Fitbit tracks your steps and other activities? It uses accelerometer technology to turn your footsteps and other movements into data, providing detailed information about your exercise habits. Here's an explanation of how Fitbit steps are measured.

How Does Fitbit Track Steps?

Fitbit uses a 3-axis accelerometer along with a step counting algorithm to keep track of your movements. When worn on your body, the accelerometer converts your physical movements into digital measurements. By analyzing these digital measurements, your Fitbit can provide surprisingly accurate information about the patterns and intensity of your workouts, including:

  • The number of steps taken.
  • The distance traveled.
  • The number of calories burned.
  • The intensity of the workout.
  • If you're biking or swimming (on certain models).

How Does an Accelerometer Work?

Accelerometers are tiny devices that can detect the direction of movement by sensing changes in gravity. They're found in a wide range of everyday technology, including smartphones and game controllers. When the screen rotates with you when you turn your phone sideways, that's an accelerometer at work.

Accelerometers rely on a technology called MEMS (Micro Electro-Mechanical Systems). A MEMS is a tiny machine that converts movement into an electronic signal that's read by a sensor. In order to track motion in many directions, the accelerometer must have multi-axis sensors. Fitbit's accelerometer has three axes (not just one, like older pedometers), which means it can track movements in any direction.

How Does Fitbit's Step Counting Algorithm Work?

Along with an accelerometer, Fitbit has a finely-tuned algorithm for counting your steps. It looks for motion patterns that meet a certain detection threshold and are indicative of walking. If the pattern and magnitude of the motions meet the standard set by the algorithm, they're counted as steps. A minor movement, like tapping your hand on a desk, won't count.

The data gathered by the accelerometer and counting algorithm are used to calculate surprisingly detailed information about your workout, which is then uploaded to your app when you sync your Fitbit. However, the algorithm isn't perfect. Fitbit sometimes undercount steps if you're walking on a soft surface such as a plush carpet, for example. It may also over count steps at times if you're driving down a really bumpy road.

How to Make Your Fitbit Count Your Steps More Accurately

Plush carpets aside, there are ways to increase the Fitbit's accuracy. For starters, it's important to manually enter your stride length in the Fitbit app, especially if your stride is longer or shorter than average. Otherwise, Fitbit uses default data based on your height, which may not match your actual stride at all.

How to Measure Your Stride Length

To measure your stride length:

  1. Pre-measure an area (in inches or centimeters) where you can take at least 20 steps, such as your driveway or a long hallway.

  2. Count your steps as you walk across the pre-measured distance, walking at least 20 steps at a normal pace.

  3. Divide the total length of the pre-measured distance (in inches or centimeters) by the number of steps you took. This provides your stride length in inches or centimeters.

  4. In the Fitbit app, go to Settings > Personal Info > Stride Length and enter your new stride length.

    You can also calculate your running stride. Just run, instead of walk, when measuring your stride length. Once you have your stride length, you can enter the data into the Personal Info screen of your Fitbit app, as shown below. Be sure to select Submit to save the information.

    Entering Fitbit Stride length
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