The Garmin Connect app displays heart rate information from the My Day view in one of two ways depending on the model of the watch.

Newer Garmin Watches

current heart rate card in Garmin Connect app

For newer Garmin watches, the above card will display the real-time heart rate information currently read by the watch you are wearing. If you are wearing more than one watch and the app detects two heart rate sources, the data from your Preferred Activity Tracker will be displayed. Touching the card will display detailed heart rate information for the current day. Touching the bar graph icon in the upper right corner will display historical heart rate information.

HRM-Pro users: This strap is not capable of displaying real-time heart rate data.

Older Garmin Watches

Early generation optical heart rate watches will display a 4-hour heart rate graph card in the Garmin Connect app:

4 hour graph card in Garmin Connect app

This includes the following watches:

Forerunner 225/235/30/35/735XT
vivoactive HR
vivosmart HR/HR+

Why Do the Low/Resting and High Heart Rate Values in Garmin Connect Differ from My Watch?

The Low/Resting and High heart rate values displayed in Garmin Connect may differ slightly from the values displayed in the heart rate widget on a watch. This is because Garmin Connect averages out the heart rate values at 2-minute intervals while watches average out the heart rate values at 15-second intervals.