**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 hours.

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).

hours to draconic month

hours to Julian month

hours to hour

hours to week

hours to tropical month

hours to Gaussian year

hours to second

hours to Julian year

hours to draconic year

hours to anomalistic year