How many seconds are in an hour?

There are exactly 3,600 seconds in one hour — calculated as 60 minutes × 60 seconds. One day contains 86,400 seconds (24 × 3,600), and one year contains approximately 31,557,600 seconds using the Julian year of 365.25 days. Use our converter above to convert any time value across all units instantly.

Why are there 60 seconds in a minute and 60 minutes in an hour?

The base-60 (sexagesimal) system originated with the ancient Sumerians and Babylonians around 2000 BCE, who favoured 60 because it is divisible by 1, 2, 3, 4, 5, 6, 10, 12, 15, 20 and 30 — making fractions far easier to express without decimals. This system was later transmitted through Greek astronomy into the modern world, where it has remained in use for time and angular measurement for over 4,000 years.

Time Conversions

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Popular Comparisons

	seconds	minutes	hours	days	years
1 minute	60	1	0.017	0.0007	0.0000019
1 hour	3,600	60	1	0.042	0.000114
1 day	86,400	1,440	24	1	0.00274
1 month (avg)	2,629,800	43,830	730.5	30.44	0.0833
1 year	31,557,600	525,960	8,766	365.25	1
Human lifespan	2,209,032,000	36,817,200	613,620	25,568	70

Time

Time is one of the seven fundamental quantities in the SI system, with the second (s) as its base unit. Since 1967, the second has been defined by atomic physics: it is the duration of exactly 9,192,631,770 cycles of the radiation corresponding to the transition between two hyperfine levels of the ground state of the caesium-133 atom. This definition, realised by atomic clocks, achieves a precision of better than one second in 300 million years — making time the most accurately measured physical quantity.

The larger units of time — minutes, hours, days, and years — are not decimal multiples of the second, reflecting their origins in ancient Babylonian astronomy, which favoured base-60 arithmetic (sexagesimal). The solar day, defined by Earth's rotation, and the tropical year, defined by Earth's orbit, are both slightly irregular, necessitating time corrections such as leap seconds and the Gregorian calendar's leap year rules. The Gregorian year of 365.2425 days corrects for the discrepancy between the calendar and the astronomical year to within 26 seconds per year.

In physics, the concept of time extends far beyond the calendar. Einstein's theories of relativity demonstrate that time is not absolute: it passes more slowly for objects moving at high velocity (time dilation) and in strong gravitational fields (gravitational time dilation). These effects are not merely theoretical — GPS satellites must account for both types of relativistic time correction to maintain the accuracy that modern navigation depends upon.

Time conversions

List of Time conversions
‣ microseconds (μs) to nanoseconds (ns)
‣ milliseconds (ms) to nanoseconds (ns)
‣ seconds (s) to nanoseconds (ns)
‣ minutes (min) to nanoseconds (ns)
‣ hours (h) to nanoseconds (ns)
‣ days (d) to nanoseconds (ns)
‣ weeks (wk) to nanoseconds (ns)
‣ fortnights (fn) to nanoseconds (ns)
‣ months (mo) to nanoseconds (ns)
‣ years (yr) to nanoseconds (ns)
‣ decades (dec) to nanoseconds (ns)
‣ centuries (c.) to nanoseconds (ns)
‣ millennia (mil.) to nanoseconds (ns)