A time converter from nanoseconds to millennia
This time converter changes a duration between seconds, minutes, hours, days and weeks, the calendar units month and year, long spans such as decades and centuries, and the tiny units computers and lab instruments use — milliseconds, microseconds and nanoseconds. Enter a number and you see it in all fourteen units at once.
People reach for it to turn 150 minutes into hours, total up project hours as days, check how many seconds a video or API timeout really is, or picture how long a billion seconds lasts (about 31.7 years). Months and years use exact Gregorian calendar averages, explained below, so long conversions stay consistent.
How to use the Time Converter
- Enter a duration in the Value box — for example 90, 2.5 or 1e9.
- Select the unit you have in From. Typing “min”, “ms” or “week” finds it fast.
- Select the unit you want in To, or use the round swap button to flip them.
- Read the converted time and its formula; choose a different Precision if you need more decimals and press Copy to grab the number.
- Scroll the list of every time unit to see the same duration in all of them, or tap a shortcut like “1 yr → d”.
Time Converter features
Fourteen units
From nanoseconds through hours and weeks to months, years, decades, centuries and millennia.
Honest calendar averages
A month is 30.436875 days and a year 365.2425 days — the true averages of the Gregorian calendar — clearly labelled in the unit names.
Computer timing units
Milliseconds, microseconds and nanoseconds for latency, frame times and benchmark results.
Decimal hours made clear
See that 2.75 hours is 165 minutes rather than “2 hours 75 minutes”.
Scientific notation
Huge or tiny durations such as 3.15 × 10¹⁰ s or 1 × 10⁻⁹ s are displayed cleanly.
How the time units are defined
The SI second is defined as 9,192,631,770 oscillations of the radiation from a caesium-133 atom, the principle behind atomic clocks. Minutes, hours, days and weeks are fixed multiples of it. Months and years are different: calendar months last 28 to 31 days and years 365 or 366, so a converter has to use an average.
| Unit | Exact length | In seconds |
|---|---|---|
| Minute | 60 s | 60 |
| Hour | 60 min | 3,600 |
| Day | 24 h | 86,400 |
| Week | 7 days | 604,800 |
| Fortnight | 14 days | 1,209,600 |
| Month (average) | 365.2425 ÷ 12 = 30.436875 days | 2,629,746 |
| Year (Gregorian average) | 365.2425 days | 31,556,952 |
| Decade | 10 average years | 315,569,520 |
| Century | 100 average years | 3,155,695,200 |
Why a year is 365.2425 days
The Gregorian calendar, introduced in 1582, adds a leap day every four years except in century years not divisible by 400. That gives 97 leap years in every 400, so the average year is 365 + 97/400 = 365.2425 days, very close to the solar year. Dividing by twelve gives the average month of 30.436875 days.
Averages are right for questions like “how many hours in a year?” (8,765.82). For the exact number of days between two real dates, use the date difference calculator, which counts actual month lengths and leap years. To add up times such as 1 h 45 min plus 2 h 30 min, the time duration calculator is quicker.
Worked examples
Minutes to hours — divide by 60. A 150-minute film is 2.5 hours, which is 2 hours 30 minutes (0.5 h × 60 = 30 min).
Hours to days — divide by 24. The famous “10,000 hours” of practice is 416.7 days of non-stop effort, or about 4.8 years at 40 hours a week.
Days to weeks — divide by 7. A 100-day plan is 14.29 weeks: 14 weeks and 2 days.
Seconds to days — divide by 86,400. One million seconds is 11.57 days; one billion seconds is 31.69 average years.
Milliseconds to microseconds — multiply by 1,000. A 16.67 ms frame (60 frames per second) is 16,670 µs. The frequency converter turns frame rates and hertz into periods directly.
Common time conversions
| From | To |
|---|---|
| 1 h | 3,600 s |
| 1 d | 1,440 min |
| 1 d | 86,400 s |
| 1 wk | 168 h |
| 1 wk | 10,080 min |
| 1 mo | 30.436875 d |
| 1 mo | 4.348125 wk |
| 1 yr | 365.2425 d |
| 1 yr | 52.1775 wk |
| 1 yr | 8,765.82 h |
| 1 yr | 31,556,952 s |
| 1 c. | 36,524.25 d |
Things to watch out for
- Decimal hours are not minutes. 1.2 hours is 1 hour 12 minutes, not 1 hour 20 minutes. Multiply the decimal part by 60.
- Not every day has 24 hours. In places with daylight saving time, the change-over days last 23 or 25 hours.
- Leap seconds. Occasionally a 61-second minute has been added to keep clocks in step with the Earth’s rotation; international timekeepers have agreed to stop adding them by 2035.
- Astronomy uses a different year. The light-year is based on the Julian year of exactly 365.25 days, slightly longer than the Gregorian average used here.
Time Converter FAQ
How many seconds are in a day?
Exactly 86,400: 24 hours × 60 minutes × 60 seconds.
How many hours are in a year?
An ordinary 365-day year has 8,760 hours and a leap year 8,784. The Gregorian average used by this time converter, 365.2425 days, gives 8,765.82 hours.
How many days are in a month on average?
30.436875 days, which is 365.2425 days divided by 12. Real months have 28, 29, 30 or 31 days.
How many weeks are in a year?
About 52.18 weeks: 52 weeks plus one day in an ordinary year, or plus two days in a leap year.
How do I convert minutes to hours?
Divide by 60. For example, 135 minutes ÷ 60 = 2.25 hours, which is 2 hours and 15 minutes.
How long is a billion seconds?
About 31.7 years. One million seconds, by comparison, is only about 11.6 days.