About the Time Unit Converter
This time unit converter changes an amount of time from one unit to another, from milliseconds up to decades. Ask it how many hours are in a year, how many days are in 10,000 minutes, or how long a million seconds really is.
Seconds, minutes, hours, days and weeks have fixed lengths. Months and years don't, because months have 28 to 31 days and leap years add a day. This converter uses average values for those, which is explained below, so you know exactly what the answer means.
How to use it
- Type the amount in Value.
- Choose the unit you have in From.
- Choose the unit you want in To.
- Read the answer, or use the table to see the same time in every unit.
Conversion formula
Every unit is stored as a number of seconds:
result = value × (seconds per From unit) ÷ (seconds per To unit)
- 1 minute = 60 s; 1 hour = 3,600 s; 1 day = 86,400 s; 1 week = 604,800 s
- 1 millisecond = 0.001 s
- 1 year = 365.2425 days = 31,556,952 s. This is the average length of a year in the Gregorian calendar, which has 97 leap years every 400 years.
- 1 month = 1/12 of that year = 30.436875 days = 2,629,746 s
- 1 decade = 10 of those years
Because the year is an average, "1 year in hours" gives 8,765.82 hours. A single common year of 365 days has 8,760 hours and a leap year has 8,784. For an exact count between two real dates, use the days between dates calculator.
Common time conversions
| Amount | Equals |
|---|---|
| 1 day | 24 h = 1,440 min = 86,400 s |
| 1 week | 168 h = 10,080 min |
| 1 average month | 30.436875 days = 730.485 h |
| 1 average year | 365.2425 days = 8,765.82 h = 525,949.2 min |
| 1 average year | 52.1775 weeks |
| 1 million seconds | 11.57 days |
| 1 billion seconds | 31.69 years |
Worked examples
Minutes to days. 10,000 minutes × 60 = 600,000 seconds. Divide by 86,400 seconds per day to get 6.944 days, or just under a week.
A million seconds. 1,000,000 ÷ 86,400 = 11.57 days. A billion seconds, by contrast, is about 31.7 years, which helps show how much bigger a billion is than a million.
Weeks to hours. A 6-week project is 6 × 168 = 1,008 hours of calendar time.
To add or subtract specific lengths of time, like 2 h 45 m + 1 h 30 m, use the time calculator.
Frequently asked questions
How many seconds are in a day?
There are 86,400 seconds in a day: 24 hours × 60 minutes × 60 seconds.
How many hours are in a year?
A 365-day year has 8,760 hours and a leap year has 8,784. This converter uses the average Gregorian year, which gives 8,765.82 hours.
How many weeks are in a year?
A 365-day year is 52 weeks and 1 day. On average, including leap years, a year is about 52.18 weeks.
How many days are in a month on average?
About 30.44 days. This converter uses 30.436875 days, which is one-twelfth of 365.2425.
How long is a million seconds?
About 11.57 days, or 11 days, 13 hours, 46 minutes and 40 seconds.
Last updated October 24, 2026. Results are estimates for education and planning — see our disclaimer.