Time Converter
Time measures the duration of events and the intervals between them. It is one of the seven base quantities in the International System of Units (SI), where the base unit is the second. Every other unit on this page, from the nanosecond to the year, is simply a larger or smaller way of counting seconds.
All Time Conversions
People convert time units constantly: turning a video length in seconds into minutes, expressing a project deadline in weeks, reading a processor benchmark in milliseconds, or estimating how many hours are in a year. Because some units (the second, minute, hour, day, and week) are fixed and exact while others (the month and year) depend on the calendar, knowing which figures are exact and which are averages helps you avoid mistakes.
Time Units Explained
The second (s) is the SI base unit. Below it are decimal subdivisions: the millisecond (ms) is one-thousandth of a second, the microsecond is one-millionth, and the nanosecond (ns) is one-billionth. Above the second, the units stop being decimal and follow tradition: 1 minute is 60 seconds, 1 hour is 60 minutes, and 1 day is 24 hours. A week is exactly 7 days. The month and year are calendar units, so they are not fixed: a common year has 365 days, a leap year 366, and calendar months range from 28 to 31 days. For conversion most tools use averages, typically a 365-day year and an average month of about 30.44 days.
How to Convert Time Units
The reliable method is to convert through the base unit, the second. First turn your starting value into seconds, then divide by the seconds in your target unit. Key exact factors: 1 minute = 60 s, 1 hour = 3,600 s, 1 day = 86,400 s, and 1 week = 604,800 s. For the decimal units, 1 s = 1,000 ms = 1,000,000 microseconds = 1,000,000,000 ns. Example: convert 3 days to hours. 3 days x 86,400 s = 259,200 s; divide by 3,600 s per hour = 72 hours. Example: convert 500 ms to seconds. 500 / 1,000 = 0.5 s. For a 365-day year, 365 x 86,400 = 31,536,000 s, which is exactly 8,760 hours.
Common Uses
- Converting media or audio length between seconds and minutes
- Reading software and network latency in milliseconds and microseconds
- Planning project schedules across days, weeks, and months
- Calculating hourly pay or billable time from total hours
- Estimating annual totals from daily or weekly figures
- Measuring scientific or electronic timing in nanoseconds
Accuracy Tips
Treat the second through the week as exact, but treat the month and year as averages unless a specific calendar date is involved. A common year is 365 days but a leap year is 366, so long-range calculations can drift by a full day per leap year. If precision matters, count actual calendar days rather than multiplying by an average month of about 30.44 days.
Frequently Asked Questions
How many seconds are in a day?
There are exactly 86,400 seconds in a day, calculated as 24 hours x 60 minutes x 60 seconds. This is the standard figure, though a rare leap second can occasionally make a specific calendar day one second longer.
How many hours are in a year?
A common year of 365 days has 8,760 hours (365 x 24). A leap year of 366 days has 8,784 hours. The average over a 4-year leap cycle is about 8,766 hours.
How many milliseconds are in a second?
There are 1,000 milliseconds in a second. A second also equals 1,000,000 microseconds and 1,000,000,000 nanoseconds.
How many days are in a month for conversion?
Calendar months vary from 28 to 31 days, so converters use an average. A common figure is about 30.44 days per month, from dividing 365.25 days by 12, which equals roughly 730.5 hours.
How many seconds are in a week?
There are exactly 604,800 seconds in a week, found by multiplying 7 days x 86,400 seconds per day. A week also equals 168 hours and 10,080 minutes.