Full name: hour
Plural form: hours
Symbol: hr
Alternate spelling: hrs
Category type: time
Scale factor: 3600
The SI base unit for time is the second.
1 second is equal to 0.00027777777777778 hr.
Valid units must be of the time type.
You can use this form to select from known units:
The hour was originally defined in Egypt as 1/24 of a day, based on their duo-decimal numbering system (which counted finger joints on each hand).