Time Unit Converter

This time unit converter changes a duration between seconds, milliseconds, minutes, hours, days, weeks, months and years. Formula: 1 h = 3600 s; 1 day = 86400 s for a fixed-duration conversion. All values go through the second, the SI unit, defined by the cesium-133 frequency of exactly 9,192,631,770 Hz. Minutes, hours, days and weeks are fixed multiples of the second (60, 3,600, 86,400 and 604,800 s), but months and years need a stated definition.

How to use the time unit converter

1. Enter the duration, for example 90.
2. Choose its unit and the target unit, such as minutes to hours.
3. Read the result: 90 minutes = 1.5 hours.

For clock times or the gap between two dates, use the time duration calculator instead; this tool converts a length of time from one unit to another.

What is time?

The second is the SI base unit of time. Minutes, hours, days and weeks are fixed multiples of it. Months and years vary in length, so converters use fixed averages such as a 365-day year or a 30-day month.

Conversion formula

The time unit converter stores every unit as a multiple of the base unit, the second (s). To convert:

value in target unit = value × (factor of source unit ÷ factor of target unit)

where each factor is the size of the unit in seconds.

Common time conversions

Time unit converter worked example

A simple time unit converter example: convert 25 minutes to hours:

1. Factor of min = 60 s
2. Factor of h = 3,600 s
3. 25 × 60 ÷ 3,600 = 0.4166667 h

Time unit reference

Reverse factors for each time unit

The reference table gives each unit in seconds. To go the other way in the time unit converter, divide by that factor; the list below does the division for you.

• Millisecond (ms), SI: 1 ms = 0.001 s, so 1 s = 1,000 ms.
• Microsecond (µs), SI: 1 µs = 1 × 10⁻⁶ s, so 1 s = 1,000,000 µs.
• Nanosecond (ns), SI: 1 ns = 1 × 10⁻⁹ s, so 1 s = 1 × 10⁹ ns.
• Minute (min), Common: 1 min = 60 s, so 1 s = 0.01666667 min.
• Hour (h), Common: 1 h = 3,600 s, so 1 s = 0.0002777778 h.
• Day (d), Common: 1 d = 86,400 s, so 1 s = 1.15741 × 10⁻⁵ d.
• Week (wk), Common: 1 wk = 604,800 s, so 1 s = 1.65344 × 10⁻⁶ wk.
• Fortnight (fn), Common: 1 fn = 1,209,600 s, so 1 s = 8.2672 × 10⁻⁷ fn.
• Month (30 days) (mo 30), Calendar (approx): 1 mo 30 = 2,592,000 s, so 1 s = 3.85802 × 10⁻⁷ mo 30.
• Month (31 days) (mo 31), Calendar (approx): 1 mo 31 = 2,678,400 s, so 1 s = 3.73357 × 10⁻⁷ mo 31.
• Year (365 days) (yr 365), Calendar (approx): 1 yr 365 = 3.1536 × 10⁷ s, so 1 s = 3.17098 × 10⁻⁸ yr 365.
• Year (366 days) (yr 366), Calendar (approx): 1 yr 366 = 3.16224 × 10⁷ s, so 1 s = 3.16232 × 10⁻⁸ yr 366.
• Decade (3650 days) (decade), Calendar (approx): 1 decade = 3.1536 × 10⁸ s, so 1 s = 3.17098 × 10⁻⁹ decade.
• Century (36525 days) (century), Calendar (approx): 1 century = 3.15576 × 10⁹ s, so 1 s = 3.16881 × 10⁻¹⁰ century.

How many seconds in a year

When a time unit converter turns years into days or seconds, the answer depends on which year you mean:

The Gregorian average reflects 97 leap years every 400 years. Astronomers use the Julian year of exactly 365.25 days, as the IAU defines it for light-years.

Minutes to hours and decimal hours

Timesheets and payroll often record time in decimal hours, so a time unit converter is handy for checking pay. Divide minutes by 60:

Hours to days works the same way: divide by 24, so 36 hours = 1.5 days. The time card calculator adds up a whole week.

Related converters and calculators

For dates, clock times and work hours:

• Time duration calculator: between two times
• Hours calculator: start and end times
• Time card calculator: weekly hours
• Time calculator: add and subtract time
• Day of the week calculator: any date

Sources

BIPM: SI Brochure; NIST: Second.

Questions about this calculator