Time Unit Converter

How to use this tool

1. Enter a value. Type the time value you want to convert in the "From" field.
2. Select units. Choose source and target time units from the dropdown menus, or use a quick value chip.
3. Read the result. The converted value appears instantly in the "To" field, and the panel below lists all supported units with copy buttons.
4. Choose definitions or share. Select a year and month definition when needed. Copy link stores the current value and settings in the URL fragment, which is not sent with page requests.

Common time conversions

Enter a duration to see its value in every supported unit at once, from picoseconds through millennia. The From and To fields remain editable in either direction. Quick values load familiar anchors such as a second, day, or week, and the year and month controls let you compare different conventions without changing the underlying conversion method.

This reference table uses the default fixed 30-day month and Julian year of 365.25 days. The converter also offers a Gregorian mean year of 365.2425 days and a Gregorian mean month of 30.436875 days. The two definitions can be selected independently. A mean month is an average duration, not a particular calendar month.

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. Prefix units use powers of ten: one picosecond is 10⁻¹² seconds, while one nanosecond is 10⁻⁹ seconds.

Notes on months and years

A year can use the Julian definition (365.25 days) or the Gregorian mean (365.2425 days). Decades, centuries, and millennia follow the selected year. Months can use a fixed 30 days or the Gregorian mean of 30.436875 days. The month definition is independent of the year selection. Neither convention models the exact span of a particular calendar month or year. For exact calendar spans, use the Days Between Dates tool.

Real-world time anchors

• 1 picosecond (ps): one trillionth of a second; useful when describing very short chip signal delays and laser pulses.
• 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): a standard 24-hour duration.
• 1 Julian year (31,557,600 s): a fixed duration used in astronomy and other calculations; it is not the exact length of each calendar year.

SI sub-second time units

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

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. It is the default year definition here and can be compared with the Gregorian mean in the controls above.
• 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 seconds, a physics scale associated with the time light takes to travel one Planck length. It is included as context, not as a selectable conversion unit.