Hour (h)
Definition
Exactly 60 minutes (3600 seconds).
History
The hour divides the day into 24 parts, a scheme inherited from ancient Egypt, and equals exactly 60 minutes or 3600 seconds. Fixed-length hours replaced older seasonal hours as mechanical clocks spread.
Where it is used
Hours structure the working day, schedules and pay, and are read off every clock.
Typical uses include schedules, work and pay.
Conversion pages
These pages convert hour to or from another unit in time.
No conversion pages use this unit yet.
Other Time units
Sources
- BIPM SI BIPM SI Brochure (2019); the second is defined by the caesium-133 transition · Dataset reviewed Sep 18, 2026