The Garmin Vivoactive 5 reads heart rate with an optical sensor on the back that shines green light into the skin, and when its readings look wrong, jump around or stop, the fit, the skin and the settings are almost always responsible. Fit comes first. Garmin advises wearing the watch snugly, about a finger's width above the wrist bone, with the sensor flat on the skin, and a looser band during the day is fine but tighten it for exercise. A watch that slides, or sits on the bone, reads badly.
The checks in more detail
Clean the back with a damp cloth to remove sweat, sunscreen and dirt, because a smudged lens scatters the light. Tattoos, dark or cold skin, a lot of arm hair and cold weather reduce accuracy, so warm up your arm and try again. Then check the settings. In the watch's settings, Wrist Heart Rate should be on, not Off or Only During Activities, and you can change the option to read all day. Under Activities, check the activity profile uses the wrist sensor and not an external strap.
If you paired a chest strap, the watch may be using it in preference to the wrist, and a flat strap battery will cause gaps. Update the watch through Garmin Connect, because heart-rate algorithm fixes are included in updates, and restart the watch. Look at Connect for the day's graph; a flat line points to a sensor that was not worn or was blocked. For accurate readings in hard sessions, such as intervals or weights, optical sensors lag behind rapid changes, and wrist flexing and tense forearms disturb them;
a chest strap is the reference choice, and the Vivoactive 5 can pair with one. Do not wear the watch over a bracelet or have a case or protector covering the sensor. If the reading is stuck at a very high or very low number at rest, restart and clean the sensor. A scratch or crack on the lens can also affect it. If the problem remains after cleaning, tightening, an update and a different wrist, contact Garmin with the serial number, because a failed sensor needs repair or replacement.
Differential
Likely causes of “Garmin vívoactive 5 heart-rate readings are missing or inaccurate”, and how to tell them apart
- 1
A loose or misplaced watch
What separates it Jumping or missing readings
How to confirm Wear it snugly above the wrist bone
- 2
A dirty sensor
What separates it Odd readings after sweat or sunscreen
How to confirm Clean the back
- 3
Wrist Heart Rate set to off or activities only
What separates it Gaps outside exercise
How to confirm Turn it on in settings
- 4
A chest strap taking priority
What separates it Gaps when its battery is low
How to confirm Charge or unpair the strap
- 5
Skin and cold conditions
What separates it Poor accuracy in the cold
How to confirm Warm up and try again
Before you touch a setting
Record this first — changing settings destroys the evidence
- How the watch is worn
- The Wrist Heart Rate setting
- Whether a strap is paired
- The activity type
Try in this order
0 of 6 completedTighten the watch
ReversibleA finger above the wrist bone.
Clean the sensor
ReversibleWith a damp cloth.
Check Wrist Heart Rate
ReversibleSet to all day.
Check for a paired strap
ReversibleAnd its battery.
Update and restart
ReversibleThrough Garmin Connect.
Contact Garmin
ReversibleIf it persists.
Model-specific
What is true of this model and not of its siblings
- Optical sensor
- It reads through the skin with green light.
- Chest strap
- The reference for intervals.
Stop boundary
When this stops being a self-service repair
- !If the sensor reads wrongly after cleaning and an update, contact Garmin with the serial number
- !For serious accuracy needs use a chest strap
- !Seek medical advice for health concerns
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Why is my Vivoactive 5 heart rate wrong?+
Usually fit, dirt or a setting.
Is a chest strap more accurate?+
Yes, for hard sessions.
Does cold weather matter?+
Yes, it reduces accuracy.
Can tattoos affect it?+
Yes.