How many seconds are in a day?

There are 86,400 seconds in a day (24 hours × 60 minutes × 60 seconds).

How many days are in a year?

A calendar year has 365 days (366 in a leap year). For conversion purposes, this tool uses 365.25 days per year - the average accounting for leap years.

How long is a month in seconds?

This tool uses a 30-day month (2,592,000 seconds) for conversions. Real months vary from 28 to 31 days.

What is a nanosecond?

A nanosecond (ns) is one billionth of a second (10⁻⁹ s). Modern CPUs operate at clock speeds measured in nanoseconds - a 3 GHz processor has a clock period of about 0.33 ns.

Time Unit Converter

Common time conversions

Value	Equivalent
1 minute	60 seconds
1 hour	60 minutes = 3,600 seconds
1 day	24 hours = 86,400 seconds
1 week	7 days = 168 hours
1 month	30 days = 720 hours (approx.)
1 year	365.25 days = 8,766 hours
1 decade	10 years = 3,652.5 days
1 century	100 years = 36,525 days

How time unit conversion works

All conversions pass through seconds as the base unit. The input value is multiplied by the source unit's second-equivalent, then divided by the target unit's second-equivalent. For example, converting 2 hours to minutes: 2 × 3,600 s ÷ 60 s/min = 120 minutes.

Notes on months and years

This converter uses a 30-day month and a 365.25-day year (the Julian year, which averages in leap years). For precise calendar-based calculations, such as the exact number of days between two dates, use the Days Between Dates tool.

Real-world time anchors

1 nanosecond (ns): light travels ~30 cm; one clock cycle of a 1 GHz processor.
1 microsecond (μs): light travels ~300 m; one instruction on a fast CPU.
1 millisecond (ms): a typical camera shutter speed; fastest human perception threshold for sound.
1 second (s): the SI base unit; defined as 9,192,631,770 cycles of cesium-133 radiation.
1 day (86,400 s): Earth’s rotation period (solar day).
1 year (31,557,600 s): Earth’s orbital period around the Sun (Julian year).

SI sub-second time units

The SI system defines several sub-second units used in computing, physics, and networking:

Unit	Symbol	Value	Context
Millisecond	ms	1/1,000 s	Network latency, camera shutter, audio samples
Microsecond	μs	1/1,000,000 s	CPU instruction timing, database query profiling
Nanosecond	ns	1/10⁹ s	RAM access times, clock cycle durations
Picosecond	ps	1/10¹² s	Chip signal propagation, ultrafast laser pulses

Astronomical time units

For very large timescales, several specialized units are used in astronomy and physics:

Julian year: exactly 365.25 days = 31,557,600 seconds. Used in astronomy and this converter for year-based conversions.
Light-year: the distance light travels in one Julian year ≈ 9.461 × 10¹⁵ m. Commonly confused as a time unit; it is actually a distance unit that uses time as its basis.
Planck time: approximately 5.39 × 10⁻⁴⁴ s - the smallest meaningful unit of time in current physics; one unit of Planck time is the time for light to travel one Planck length.