How accurate are Fitbit devices?

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 band. During workouts and sleep, we recommend wearing the classic band. Make sure the band fits securely but isn't too tight.

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

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 calculate my daily activity?

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 activity with my Fitbit device?

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.

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.

If you're walking or running outside, use GPS to capture your route, pace, and distance. For more information, see How do I use GPS on my Fitbit device?

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 add, edit, or delete Fitbit data and activities?

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.

If you feel that your step count and distance are inaccurate, confirm the following are correct in the Fitbit app:

• Your wrist settings (For more information, see Does the wrist I wear my device on affect accuracy?)
• Your height (For more information, see How do I manage my Fitbit profile?)

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 does my Fitbit device calculate my daily activity?

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. Confirm your tracker is set to WORN on Wrist (Inspire 3) or On Wrist (Inspire and Inspire 2) when you wear your tracker on your wrist, and CLIPPED on Body (Inspire 3) or On Clip (Inspire and Inspire 2) when you wear your tracker in the clip accessory. For more information, see How do I wear my Fitbit device?

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

All devices with GPS sensors require a direct path to GPS satellites to calculate location. A weak GPS signal might affect the accuracy of your route and other activity data. Your device uses your step count to calculate distance until it finds a signal, so the total distance calculated for a workout may be slightly less accurate when GPS isn't available for the entire time.

To learn more, see GPS.gov.

To improve the accuracy of your scale's readings:

• Use while barefoot.
• Make sure your feet are dry before weighing yourself.
• Place the scale on a hard, flat surface during use.
• Balance your weight evenly between both feet when you stand on the scale.
• Weigh yourself at the same time each day to see consistent trends. Your weight naturally varies over the course of the day.
• Fitbit scales needs to recalibrate if you move it between measurements or store it sideways when not in use. Up to 2 weigh-ins might be required before your scale displays accurate measurements.
• For Fitbit Aria and Fitbit Aria 2, if you turn lean mode on or off, your body fat percentage reading can be affected. For more information, see How do I use my Fitbit scale?
• For the most accurate data, your height and sex must be correct in your Fitbit profile. To update your profile, see How do I change the units of measurement in my Fitbit account?

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.