About Time Converter
Time Converter expresses a duration in any of eight units, from milliseconds up through seconds, minutes, hours, days, weeks, months and years. It handles the everyday cases — turning a number of seconds into minutes and hours, or a project length in weeks into working days — and the unit a sensor or log file reports in.
The units below a week are exact: a minute is 60 seconds, an hour is 3600 seconds and a day is 86400 seconds, all fixed by definition. Months and years are not. The tool uses average lengths of 30.4375 days for a month and 365.25 days for a year, which is what makes a year average out to 365.25 days across the leap-year cycle. Those averages mean a conversion involving months or years is an approximation: a specific calendar month may be longer or shorter, and a specified year may have 365 or 366 days.
The output is a bare number rounded to eight decimal places, with the unit implied by your second selection. For calendar-accurate work — payroll periods, deadlines, billing cycles — treat the month and year conversions as estimates and compute the actual dates instead.
How to use Time Converter
- 1 Enter the duration to convert.
- 2 Choose the unit the duration is in, from milliseconds to years.
- 3 Choose the target unit and run the conversion.
Frequently asked questions
Is a month exactly 30 days here?
No, it is 30.4375 days, which is 365.25 divided by 12. That average accounts for the varying lengths of calendar months, so converting a specific month of 28 or 31 days through this tool will not match the calendar exactly.
Why is a year 365.25 days?
Because that is the average length of a year across the four-year leap cycle: three years of 365 days and one of 366. A single named year is either 365 or 366 days, so the average is a simplification that suits long spans better than short ones.
Is a day exactly 24 hours?
In this tool, yes — the conversion is a fixed 86400 seconds. Real days vary slightly because of the Earth's rotation, and daylight saving shifts the wall-clock length of a day, but neither is modelled here because the tool measures durations rather than calendar dates.
Which units are exact?
Everything from milliseconds to weeks. Millisecond, second, minute, hour, day and week relationships are all fixed integers, so conversions among them carry no approximation. Only months and years, being averages, introduce rounding.
Free, online, and private
Free to use
Time Converter is completely free. There is no account to create, no login, and no hidden charge or usage limit.
Runs online in your browser
It is a free online tool that runs entirely in your browser. Nothing to download or install — open the page and start using it right away.
Your data stays private
All processing happens locally on your device. Your input is never uploaded, stored, or tracked, so it never leaves your browser.
How Time Converter behaves in detail
These are the specifics of this implementation — the exact ranges, defaults and fixed settings you are working with.
| Parameter | Value |
|---|---|
| Units covered | 8 — ms, s, min, h, days, weeks, months and years |
| Conversion basis | second |
| Month definition | 2,629,800 s = 30.4375 days, exactly one twelfth of a Julian year |
| Year definition | 31,557,600 s = 365.25 days — the Julian year, not 365 |
| Result precision | 8 decimal places, from a starting Value of 1 |
| Default pair | h → min |
Compiled from the implementation of this tool and checked against it by itoolnet.
What Time Converter does not do
Knowing the edges of a tool saves more time than another list of its features. These are the cases where it will not do what you might expect.
- Months are a flat 30.4375 days, not calendar months. Three months therefore converts to 91.3125 days whatever the starting date, so a quarter measured this way can be a day or two away from the same quarter read off a real calendar.
- The year is 365.25 days. Most contracts, and the Gregorian calendar itself at 365.2425, use a shorter year, so a multi-year conversion can be out by roughly 11 minutes per year — around an hour over a decade — with nothing in the output stating which year length was applied.
- This is a pure seconds table, so nothing here understands dates. A month cannot be added to a specific date, February is not shorter than January, leap days are invisible, and no time-zone offset is involved — calendar arithmetic belongs to the date tools instead.
Tested and documented by itoolnet, the team that builds and maintains this site.