Time unit converter
Seconds, minutes, hours, days, weeks, months and years.
Calculator inputs
Results
Enter your values and press “Calculate” to see the result.
In short
- What it calculates
- Seconds, minutes, hours, days, weeks, months and years.
- Formula used
1 min = 60 s · 1 h = 3600 s- Example
- 1 hour in other units:
Time unit converter
Useful for project estimates, duration maths and technical conversions from milliseconds to hours.
For differences between specific dates, the days between dates calculator is a better fit.
How it works
Every unit is expressed in seconds. A month is taken as a twelfth of the mean year (30.44 days) and a year as 365.25 days, which absorbs the leap day.
Formula
1 min = 60 s · 1 h = 3600 s
1 day = 86,400 s · 1 week = 604,800 s
1 month = 2,629,800 s · 1 year = 31,557,600 s
Worked example
1 hour in other units:
3,600 seconds
60 minutes
0.0417 days
0.00595 weeks
Explanation
A year is not exactly 365 days
The Earth takes about 365.2422 days to orbit the Sun. That leftover quarter day is why leap years exist. But since it is not exactly a quarter, the Gregorian calendar adds a correction: years divisible by a hundred are not leap years unless they are also divisible by four hundred. That is why 1900 was not a leap year and 2000 was.
Months of variable length
A month is not a fixed unit: it runs from 28 to 31 days. That is why financial calculations often use thirty-day months, and why adding a month and adding thirty days give different results. Any conversion using a month as a unit is necessarily an approximation.
Where the 24 hours come from
The Egyptians divided the day into twenty-four parts using a duodecimal system based on finger bones. The sixty minutes and sixty seconds come from the Babylonian sexagesimal system, chosen because sixty divides exactly by many numbers.
Very small units
A millisecond is a thousandth of a second, a microsecond a millionth and a nanosecond a billionth. In that last span, light travels about thirty centimetres.
Frequently asked questions
Why is a year 365.25 days?
That is the mean Julian year, spreading the leap day across four years. For specific calendars use the date calculators.
What about months of different lengths?
Here a month is an average. If you need calendar accuracy, the days between dates tool counts each month at its real length.
Why was 2000 a leap year and 1900 not?
Because years divisible by a hundred are not leap years unless also divisible by four hundred. It is the correction that aligns the calendar with the real length of the year.
How many days does a month have in calculations?
It depends on context. Financial calculations often use thirty days, but a real month runs from twenty-eight to thirty-one.
Need to calculate something else?
These tools are often used alongside this calculator.
Add hours
Work with HH:MM times without tripping over base 60.
Days between dates
Count the days, weeks and months separating any two dates.
Hours worked
Work out effective working time after breaks, night shifts included.
Data
Bytes, kilobytes, megabytes, gigabytes and terabytes, decimal and binary.
Km to miles
Turn any distance from kilometres into statute miles using the official factor.
Kg to pounds
Turn any weight from kilograms into pounds with the exact international factor.