Time Unit Converter
Convert any duration between nanoseconds and millennia. Pick the two units, see the answer instantly, and get the same duration broken down into days, hours, minutes and seconds.
Last updated:
Used for months, years, decades and longer.
How to use the Time Unit Converter
- Enter the duration as a plain number (decimals are fine).
- Choose the From and To units, e.g. seconds to hours.
- Pick a year length if you convert months, years or decades. Gregorian average is the default.
- Read the result and the d:h:m:s breakdown in the results panel.
- Use the table to see every unit at once, or press Copy results.
How the time unit conversion works
Every unit is first turned into seconds, the SI base unit of time, and then divided by the size of the target unit:
result = value × (seconds per source unit) ÷ (seconds per target unit)
Units up to a week are fixed: a minute is 60 s, an hour 3,600 s, a day 86,400 s and a week 604,800 s. Months and years are not fixed lengths in the calendar, so the converter uses averages that you can choose.
| Unit | Equals | In seconds |
|---|---|---|
| 1 nanosecond (ns) | 0.001 µs | 0.000000001 |
| 1 microsecond (µs) | 1,000 ns | 0.000001 |
| 1 millisecond (ms) | 1,000 µs | 0.001 |
| 1 minute | 60 s | 60 |
| 1 hour | 60 min | 3,600 |
| 1 day | 24 h | 86,400 |
| 1 week | 7 days | 604,800 |
| 1 average month (Gregorian) | 30.436875 days | 2,629,746 |
| 1 Gregorian year | 365.2425 days | 31,556,952 |
| 1 Julian year | 365.25 days | 31,557,600 |
| 1 decade (Gregorian) | 3,652.425 days | 315,569,520 |
Where each unit is used
- Nanoseconds and microseconds: CPU and memory timings, network latency inside a data center, camera shutter electronics. Light travels about 30 cm in one nanosecond.
- Milliseconds: web page load times, ping, audio latency, reaction time (a typical human reaction is roughly 200–250 ms). One frame at 60 fps lasts about 16.7 ms.
- Seconds to hours: timers, video length, work logs and timeouts in software settings.
- Days to decades: project planning, warranties, loan terms, ages and historical periods.
Tips
- For durations measured in calendar terms (e.g. "3 months from today"), use a date calculator, because real months have 28–31 days. This converter uses averages.
- Unix time counts seconds; JavaScript and many APIs count milliseconds. Divide by 1,000 to switch from ms to s.
- Leap seconds are not included: a day is always 86,400 s here, which matches how almost all software measures time.
Frequently asked questions
How many seconds are in a day, a week and a year?
A day has 86,400 seconds (24 × 60 × 60), a week has 604,800 seconds, a 365-day year has 31,536,000 seconds and an average Gregorian year (365.2425 days) has 31,556,952 seconds.
How long is a month in this converter?
Months vary from 28 to 31 days, so the converter uses an average month of one twelfth of a year. With the Gregorian year that is 30.436875 days, or 2,629,746 seconds.
Which year length should I choose?
Use the Gregorian average (365.2425 days) for calendar-based durations over many years. Astronomy and the light-year use the Julian year of exactly 365.25 days. Pick 365 days for a single non-leap calendar year.
How do I convert seconds to days, hours, minutes and seconds?
Divide by 86,400 for whole days, take the remainder and divide by 3,600 for hours, then by 60 for minutes; what is left is seconds. For 100,000 s that is 1 day, 3 hours, 46 minutes and 40 seconds.
How many milliseconds, microseconds and nanoseconds are in a second?
One second is 1,000 milliseconds, 1,000,000 microseconds and 1,000,000,000 nanoseconds. Each step is a factor of 1,000.
Why do years and decades give slightly different answers on other sites?
Sites use different year lengths: 365, 365.25 or 365.2425 days. Over a decade the difference between 365 and 365.2425 days is about 2.4 days, so check which definition a source uses.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.