Why Smartwatch Heart Rate Jumps

Why Your Smartwatch Heart Rate Jumps

The makers point to six causes:

1. A loose or low watch. Garmin says a loose watch that shifts as your arms swing can lock onto your cadence instead of your heart rate.
2. Wrist movement. Apple names irregular movements like tennis or boxing; Google names bike riding and weightlifting, which bend the wrist.
3. Cold, which Apple, Google and Garmin say affects blood flow to the skin.
4. A dirty or blocked sensor: body hair and dirt under the band (Samsung), sunscreen and lotion buildup (Garmin).
5. Some tattoos, whose ink can block the sensor's light (Apple, Garmin).
6. A setting: tracking turned off (Google) or set to manual measurement only (Samsung).

How to Fix Smartwatch Heart Rate That Jumps

Try these in order; restart comes last, as in Google's Fitbit steps.

Fix 1: Wear It the Way Your Watch Maker Recommends

Use your maker's fit rule:

• Apple Watch: snug on top of your wrist, with the heart rate sensor close to your skin. Apple suggests tightening the band for workouts and loosening it after.
• Pixel Watch and Fitbit: on top of your wrist with the back touching your skin, a finger's width above your wrist bone when you're not exercising. For exercise, Google says "a bit tighter and higher," snug but not constricting.
• Galaxy Watch: "snugly above the wrist," Samsung says, without fastening the band too tightly.

Fix 2: Wipe the Sensor

Samsung says to wipe the sensor with a soft, clean, dry cloth, then adjust the watch to sit above your wrist. Clean a Garmin sensor with fresh water and a soft cloth, and dry the watch before wearing it.

Fix 3: Check Heart-Rate Tracking Is On

Turn tracking back on if it's off or set to manual:

• Pixel Watch and Fitbit: tracking is on by default. If you turned it off, open the Settings app on the watch and tap Heart Rate.
• Galaxy Watch (Wear OS): open Samsung Health on the watch, swipe to the very bottom, tap Settings, then Heart rate, and choose Measures continuously.
• Apple Watch: in the Watch app on your iPhone, tap Privacy to check Heart Rate; on the My Watch tab, tap Passcode to check Wrist Detection. With it off, Apple says background heart rate measurements aren't taken.

Fix 4: Hold Still for Spot Checks, and Warm Up

For a spot check, Samsung says not to talk, yawn or breathe deeply while measuring. If a Fitbit goes blank or freezes during vigorous exercise, Google says to relax your wrist and stay still for up to 10 seconds; the number may spike or dip as it finds your heart rate. On cold mornings, Garmin suggests warming up for 10 to 15 minutes on the activity profile screen before you start the timer.

Fix 5: Sync the Watch

Recorded heart rate shows in your watch's phone app:

1. Open Health on iPhone, the Google Health app (formerly the Fitbit app) for Pixel Watch and Fitbit, or Samsung Health for Galaxy Watch.
2. If the watch shows your heart rate but the app doesn't, Google says the watch could be disconnected from the app. Fix that with Smartwatch Not Syncing? Apple Watch, Garmin, Fitbit Fixes.

Fix 6 (Last): Restart the Watch

Restart the watch, then check again; Google puts it after the other steps. On a Garmin, search "Restart" in your owner's manual and update the software. Other brands' steps are on How to Reset Any Smartwatch.

By Watch Brand

Each maker adds details of its own.

Apple Watch

Apple Watch Series 12 and Apple Watch Ultra 4 use green LEDs continuously during the day, measuring as often as every five seconds, even in motion. For the Heart Rate app itself, see How to Check Heart Rate on Apple Watch.

• Related Apple Watch tracking: How to Track Steps on Apple Watch.

Google Pixel Watch and Fitbit

For Fitbit, Google says tracking may not work with some accessory bands, especially loose ones, and recommends the band that came with the device. Fitbit Sense, Sense 2, Versa 3 and Versa 4 don't let you turn tracking off.

Samsung Galaxy Watch

Samsung says to remove the protective plastic from the heart rate sensor before measuring, to avoid third-party bands, and to take a brief break before a mid-workout measurement.

Garmin

Garmin wants the watch above the wrist bone, "snug but comfortable," so it doesn't shift. For wrist-flexing activities such as rowing, move it slightly farther up or wear a Garmin heart rate monitor strap.