Hour (h)
The hour, symbol h, is 60 minutes or 3,600 seconds. It began in ancient times, when people divided the day into 24 parts based on the sun’s movement. This method of dividing the day has remained throughout history. Today, hours organize daily life—jobs, TV, and transport rely on them. The hour is not an SI unit, but it is widely used for convenience and accuracy.
Day (d)
The day, symbol d, is the time it takes Earth to rotate once. A day is 24 hours or 86,400 seconds. Because Earth’s spin changes a little, days can vary, so leap seconds are sometimes added to atomic clocks. The day is a key part of human life, shaping calendars, routines, and events in all cultures. It is one of the most fundamental and widely recognized time units.
Other Relevant Conversions
s → ms s → µs s → min s → h s → d s → wk s → yr ms → s ms → µs ms → min ms → h ms → d ms → wk ms → yr µs → s µs → ms µs → min µs → h µs → d µs → wk µs → yr min → s min → ms min → µs min → h min → d min → wk min → yr h → s h → ms h → µs h → min h → d h → wk h → yr d → s d → ms d → µs d → min d → h d → wk d → yr wk → s wk → ms wk → µs wk → min wk → h wk → d wk → yr yr → s yr → ms yr → µs yr → min yr → h yr → d yr → wk