How can Fitbit help me track my temperature?

Track your temperature over time to help identify patterns and spot trends.

For instructions on how to change the temperature units you see on your Fitbit device or in the Fitbit app, see How do I change the units of measurement in my Fitbit account?

Core temperature

Core temperature is the temperature inside your body, which is usually taken with a thermometer. It typically varies less than your skin temperature.

On Sense and Versa 3, log your core temperature from the Today app :

  1. Open the Today app on your watch.
  2. Tap the Core Temp tile thenLog.
  3. Use the - and + icons to set your core temperature thenSave.

With Sense and Sense 2, log your core temperature in the Fitbit app on your phone:

  1. From the Today tab in the Fitbit app, tap the Temperature tile . If you don’t see the Temperature tile, add it from the Discover tab thenHealth & Fitness statsthenTemperature.
  2. Tap the + icon at the top of the screen.
  3. Enter your core temperature thenSave.

From the Today tab in the Fitbit app, tap the Temperature tile . A graph of your logged core temperatures appears, as well as a list of your temperature history below.

  • For Sense and Sense 2, swipe left on the graph to switch to your core temperature logs.

Your core temperature naturally varies, but healthy individuals typically have a temperature between 97°F to 99°F (36°C to 37°C) (source). A temperature greater than 100.4°F (38°C) indicates a fever (source).

  • Ovulation - Core temperature typically rises during ovulation (source).
  • Time of day - Core temperature is typically lower in the morning and rises during the late afternoon and evening (source).
  • Sleep - Core temperature typically drops during sleep (source).
  • Fever - Core temperature typically rises when fighting an infection and individuals can develop a fever (source).

Note that the method you use to check your temperature can affect accuracy. For tips on how to more accurately take your temperature, see mayoclinic.org.

Skin temperature

Skin temperature is the temperature on the skin's surface. It typically varies more than your core temperature, since warming up or cooling down the skin is one way the body regulates itself and keeps core temperature stable. Some Fitbit devices use a sensor to estimate your personal baseline skin temperature, based on up to 30 days of data. Each morning, you can see how your skin temperature last night compares to your personal baseline. Note that you see this information as your skin temperature variation (whether your skin temperature was higher or lower than your personal baseline).

Fitbit Sense and Fitbit Sense 2 use a dedicated sensor to estimate your skin temperature variation each night. Fitbit Charge 4, Fitbit Charge 5, Fitbit Inspire 2, Fitbit Inspire 3, Fitbit Ionic, Fitbit Luxe, and Fitbit Versa series surface your nightly skin temperature variation through existing sensors.

Everyone has a different temperature baseline. When you wear a compatible Fitbit device to sleep, it checks your skin temperature every minute. When the Fitbit app has at least 3 nights of skin temperature data, it estimates your personal baseline temperature. As you continue to wear your Fitbit device to sleep, the Fitbit app uses up to 30 nights of data to adjust your baseline temperature.

  1. Wear your device for at least a full day, including to sleep at night.
  2. In the morning, open the Fitbit app and tap the Temperature tile.
    Temperature tile in the Fitbit app
  3. Tap the tile to see a history of your sleeping skin temperature variations, along with any core temperature readings you manually recorded.
    Bar graph of the user's skin temperature variations over the previous week
  4. Tap a log to see a minute-by-minute record of your skin temperature variation throughout the night.
    Line graph of the user's sleeping skin temperature over the previous night

You may notice more variation when you look at your minute-by-minute data, as compared with your overall skin temperature variation for the night. Your skin temperature changes throughout the night as you move around and your body regulates itself. Your overall variation is based on your average skin temperature during the night.

  1. Wear your device for at least 3 nights.
  2. In the morning, open the Fitbit app and tap the Health Metrics tile .
  3. Swipe up to find the Skin temperature tile.
  4. Tap the tile to see more details, including your historical data.

Skin temperature typically varies over the course of a night. Factors that may cause skin temperature to vary include changes in room temperature, bedding, circadian rhythm, menstrual cycle, or the onset of a fever. Note that significant changes in ambient temperature may negatively impact skin temperature tracking.

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