Garmin's optical heart rate article says the sensor shines green light through the skin and reads reflected changes in blood volume, and its warning states that Garmin wearables are not medical devices and only estimate. Its tips: wear silicone or fabric bands, above the wrist bone, snug but comfortable and not shifting. Restart and update the watch, and pick the activity profile that matches the workout because heart rate calculations differ by activity.
Warm up for 10 to 15 minutes on the activity profile screen before starting the timer, since limited blood flow early in a workout makes readings less consistent. Confirm your user profile, including age, height, weight and max heart rate, and clean the sensor of sunscreen and lotion with fresh water and a soft cloth. Tattoo ink can block the light, so wear the watch on skin without tattoos. Cold, cadence lock and swimming limits are covered in the article.
Differential
Likely causes of “Garmin watches heart-rate readings are missing or inaccurate”, and how to tell them apart
- 1
The watch is too loose or below the wrist bone
What separates it The readings drop or double during running because the watch is too loose or below the wrist bone
How to confirm Wear it snug above the wrist bone on a silicone or fabric band
- 2
No warm-up
What separates it The first minutes read erratically because there was no warm up
How to confirm Warm up 10 to 15 minutes on the activity screen before starting
- 3
The wrong activity profile
What separates it The reading looks wrong for the workout because the wrong activity profile was used
How to confirm Choose the profile that matches what you are doing
- 4
A dirty sensor
What separates it The readings vary day to day because of a dirty sensor
How to confirm Clean the sensor of sunscreen and lotion, and wear it again
- 5
A tattoo or cold skin
What separates it There is no reading on one wrist because of a tattoo or cold skin
How to confirm Move the watch to skin without a tattoo, or warm up
- 6
A wrong user profile
What separates it The zones look off because of a wrong user profile
How to confirm Correct age, height, weight and max heart rate
Before you touch a setting
Record this first — changing settings destroys the evidence
- Which activity profile and what the reading did
- Which wrist, which band and how the watch fits
- Whether a chest strap agrees with the watch
Try in this order
0 of 7 completedCheck the fit
ReversibleCheck the fit, by wearing it snug above the wrist bone, and use a silicone or fabric band.
Restart and update
ReversibleRestart and update, by restarting the watch and updating it with Garmin Express, and then test again to see whether it helped.
Pick the right profile
ReversiblePick the right profile, by choosing the activity profile that best matches your workout, and then test again to see whether it helped.
Warm up first
ReversibleWarm up first, by warming up 10 to 15 minutes before you start the timer.
Check your profile
ReversibleCheck your profile, by confirming age, height, weight and max heart rate in Garmin Connect.
Clean the sensor
ReversibleClean the sensor, by wiping off sunscreen and lotion with fresh water and a soft cloth.
Try a chest strap
ReversibleTry a chest strap, by pairing a Garmin HRM strap to compare the readings, and then test again to see whether it helped.
Model-specific
What is true of this model and not of its siblings
- Where the sensor is
- Garmin's article describes an optical sensor on the back of the watch that shines green light into the skin, and says sunscreen and lotion on the sensor can block it.
- Bands
- Garmin's tip is to use silicone or fabric bands for the most accurate results, and to wear the watch above the wrist bone.
- Repair cost
- Fit and settings cost nothing. A Garmin HRM chest strap is an optional extra of a few tens of dollars. A dead sensor is service: Joe's Gaming and Electronics charges a $50 diagnostic fee if you decline a quote, and WalkingSolar quotes about $50 to $80 for a battery replacement through Garmin.
- Other models this page answers
- These steps also fit models epix Pro (Gen 2), Forerunner 265, Venu 3/3S, Instinct 2X Solar, S70.
Stop boundary
When this stops being a self-service repair
- !If the sensor lens is cracked or readings are absurd on both wrists, contact Garmin Support
- !If you have symptoms such as chest pain or dizziness, contact a doctor rather than relying on the tracker
- !If a chest strap agrees, the fit and profile are the fix
Evidence ledger
Sources behind this answer
Fit, restart, activity profile, warm-up, profile, sensor cleaning, tattoos and limitations.
Updating the watch.
External sensors when readings are poor.
Restarting the watch.
The company and its wearables line.
Exact questions
Common questions
Why is my Garmin heart rate wrong?+
Usually fit, no warm-up or the wrong profile. Follow Garmin's accuracy tips.
Is it medical grade?+
No. Garmin says its wearables are not medical devices and only estimate.
Do tattoos matter?+
Yes. Garmin says tattoo ink can block the sensor's light.
Where do I wear it?+
Above the wrist bone, snug but comfortable, per Garmin.
Should I warm up?+
Garmin recommends 10 to 15 minutes on the activity profile screen before starting.
Does swimming work?+
Wrist heart rate has limits in water; Garmin has a separate FAQ on wrist heart rate while swimming.
Do I need a chest strap?+
For irregular sports or poor blood flow, a chest strap is more reliable.
Does the update help?+
Garmin says restart and update as a first step.