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How accurate are Fitbit devices?

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Fitbit is dedicated to developing the most accurate fitness devices on the market. 

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Why does my step count differ depending on where I wear my Fitbit device?

If you wear a wrist-based Fitbit device and move your body while keeping your arms still (or vice versa), you may see a slightly different step count than if you wear a device clipped to your clothing. 

If you wear your device in a loose-fitting accessory such as a bangle or pendant, you may see a slightly different step count than if you wear a classic wristband. During workouts and sleep, we recommend wearing the classic wristband. Make sure the wristband fits securely but isn't too tight. 

For more information, see How do I wear my Fitbit device? and How do I track my heart rate with my Fitbit device?

Why does my Fitbit device count extra steps?

Fitbit devices have a finely-tuned algorithm for step counting. The algorithm is designed to look for intensity and motion patterns that are most indicative of people walking and running. When working at a desk, cooking, or performing other activities with arm movements, a device on your wrist may add some steps. When you’re doing activities that involve arm movement—such as working or cooking—you often walk a few steps in-between stationary periods as well, so the device tries to give you credit for those steps. For most customers, the number of extra steps added by arm-based movement isn’t significant when compared to your overall stats. For more information, see How does my Fitbit device count steps?

Why does my Fitbit device count steps when I’m riding a bike? 

When you ride a bike on bumpy trails, your device may add some steps. For most customers, the number of extra steps added when riding a bike isn’t significant when compared to your overall stats. If your device has an Exercise app, make sure you choose the Bike exercise before starting your workout. If you use automatic tracking to detect your bike ride, make sure the Outdoor Bike exercise is set to be automatically recognized. For more information, see How do I track my exercise and activities with Fitbit?

Why does my Fitbit device count extra floors?

Fitbit devices detect floors with an altimeter, which is a sensor that calculates altitude based on atmospheric pressure. Your device is designed to detect pressure changes based on elevation gain, but other types of pressure changes—such as a gust of wind, a weather change, or opening a door—can occasionally cause your device to register extra floors. Your device registers 1 floor when you climb about 10 feet, which is the average between residential and commercial floor heights. If you climb long staircases you may find that the floor count on your device doesn’t match the number of floors you climbed when the staircase is taller than 10 feet.

Will my device count steps if my arms aren't moving?

If you're doing something like pushing a stroller or shopping cart, your wrist-based device will count your steps but the total may be slightly lower than usual.

Will my device pick up steps when I’m in the car or riding in a vehicle?

Your device has been tested against driving and riding in buses, trains, and other public transportation and shouldn’t add steps when you’re traveling under normal conditions. On bumpy roads or in a car with a stiff transmission your device may add some steps. For most customers, the number of extra steps added when driving isn’t significant when compared to your overall stats. If you want to remove the steps from your daily total, manually log the driving activity for the time you were in a vehicle. For more information see How do I edit or delete Fitbit data and activities?

Does the wrist I wear my device on affect accuracy?

For wrist-based devices, it's important to specify whether you wear the device on your dominant or non-dominant wrist during setup:
  • The dominant wrist setting decreases the sensitivity of step counting and should reduce any over counting of steps when your body is not moving. Your dominant hand is the one you use for writing and eating.
  • The non-dominant wrist setting increases the sensitivity of step counting and should reduce any under counting of steps.
To start, the Wrist setting is set to non-dominant. Change your wrist setting in the Fitbit app. 

What can I do if my step count seems inaccurate?

If you feel that your step count and distance are inaccurate, confirm the following are correct in the Fitbit app: Since we use height to estimate your walking and running stride lengths, you may want to measure and manually adjust these values if your legs are longer or shorter than average. For more information, see How do I measure and adjust stride length for my Fitbit device?

Sometimes, when you start walking, your steps may not update on your device right away. After about 10-15 continuous steps, you'll notice the steps catch up and start updating in real time with each step you take.

When you wear a Fitbit device in a clip, make sure you wear it properly. Make sure Inspire is set to On Wrist when you wear it on your wrist and On Clip when you wear it in the clip accessory. For more information, see How do I wear my Fitbit device?

If my device measures heart rate or GPS, how reliable is this data?

For more information, see How do I track my heart rate with my Fitbit device? and How accurate is GPS?

How can I get the most accurate reading on my Fitbit scale?

To improve the accuracy of your scale's readings, try the following:

  • If you pick up and move your scale between measurements, or store it sideways against a wall when not in use, the scale will calibrate the next time it's used. You may need to weigh yourself 2 or more consecutive times before the scale calibrates and shows consistent measurements.
  • Place your scale on a hard surface during use. Carpet, linoleum, or any other flooring with resilience may affect the accuracy of the scale's readings.
  • Your weight and body fat percentage naturally vary over the course of a day and can change based on what you eat and drink as well as your body stance, age, height, level of exercise, and perspiration. For consistency, weigh yourself first thing in the morning before eating, drinking, or exercising. If you’re wearing clothes, dress lightly and remove your shoes and socks.
  • Your body fat percentage may be affected if you weigh yourself while holding a heavy object.
  • If you turn lean mode on or off, your body fat percentage reading can be affected. For more information, see About Fitbit Aria 2.
  • For the most accurate BMI and body fat percentage result, your height, age, and sex must be correct in your Fitbit profile. To update your profile, choose a section below:
    • Fitbit App
      1. From the Fitbit app dashboard, tap the Account icon User-added image.
      2. Tap > Personal Stats.
      3. Tap a stat and update it.
    • Fitbit.com Dashboard
      1. On the fitbit.com dashboard, click the gear icon (User-added image).
      2. Click Settings.
      3. Find the category you want to change and update it.

Fitbit Aria and Fitbit Aria 2 estimate your body fat percentage using body impedance. Because several different methods can determine body fat percentage and none are 100% accurate, the scale's body fat reading may not perfectly match other scales or manual methods, such as calipers.

Why does my weight differ between Fitbit Aria and Aria 2?

Aria 2 has been redesigned to provide more accurate measurements than Aria. For this reason, you may notice different readings between the scales.
Last updated: March 23, 2019
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