Time Unit Converter
Convert between seconds, minutes, hours, days and years.
Results update as you type.
How it works
A time unit converter restates a duration in a different unit, moving between milliseconds, seconds, minutes, hours, days, weeks, 30-day months and 365-day years. It reduces your figure to seconds, the SI base unit for time, then scales out to the unit you choose, so one mechanism covers stopwatch splits, project timelines, scientific measurements and everyday scheduling alike. This matters because time appears in many units and the conversions are not as simple as decimal shifts. There are sixty seconds in a minute, sixty minutes in an hour and twenty-four hours in a day, so turning 5,400 seconds into hours and minutes by hand is easy to get wrong. Programmers routinely juggle milliseconds and seconds; scientists work in fractions of a second; planners think in days, weeks and months. A converter removes the mental arithmetic and the risk of a dropped factor of sixty. The convert-through-seconds method is used because every unit here has a fixed number of seconds — a minute is 60, an hour 3,600, a day 86,400 — so pivoting through that base keeps results exact and needs only one factor per unit. Note that this tool uses conventional 30-day months and 365-day years for quick estimates; it is deliberately named a time-unit converter rather than a calendar tool, because real months vary in length and leap years add a day. Developers, scientists, students and planners all use it whenever a duration lands in an inconvenient unit.
Convert to seconds via known factors, then to the target unit
The input is multiplied by its unit's fixed number of seconds to express the duration in seconds, then divided by the target unit's second value to complete the conversion. The sub-day units are exact by definition, while the month is fixed at 30 days and the year at 365 days for estimation. Because each unit is a constant number of seconds, chaining through that single base is exact for the definitions used, with one stored factor per unit.
Source:International System of Units (SI) — NIST
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter value, from and to.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Converted time updates instantly as you type — no button to press.
Frequently asked questions
How many seconds are in a day?
Exactly 86,400 seconds, found by multiplying 24 hours by 60 minutes by 60 seconds. A week is seven times that, 604,800 seconds. These figures are exact for a standard day. Note that rare leap seconds, added occasionally to keep clocks aligned with Earth's rotation, can make a specific real day one second longer, but this converter uses the standard 86,400 for everyday calculations.
How long is a month in this converter?
This tool treats a month as exactly 30 days, or 2,592,000 seconds, for quick estimation. Real calendar months range from 28 to 31 days, so for precise date arithmetic you should use a date-difference calculator instead. The 30-day convention is common in finance and rough planning because it gives a consistent, round figure that is easy to reason about across many months.
Why is a year 365 days here and not 365.25?
This converter uses a flat 365-day year, 31,536,000 seconds, for simple estimates rather than the astronomical 365.25-day figure that accounts for leap years. Over four years the quarter-day difference adds up to one extra day, which is why the calendar inserts February 29. For exact multi-year durations spanning leap years, use a dedicated date calculator rather than this unit converter.
How do I convert milliseconds to seconds?
Divide the millisecond figure by 1,000, since one second is 1,000 milliseconds. So 2,500 milliseconds is 2.5 seconds. To reverse it, multiply seconds by 1,000. Milliseconds are widely used in programming, web performance and audio timing, where sub-second precision matters, so converting cleanly between the two is a routine task for developers and engineers.
Why convert time through seconds?
The second is the SI base unit for time, so every other duration unit has a fixed number of seconds attached to it. Using the second as the pivot means the converter needs only one factor per unit rather than a separate rule for each pair, and it keeps results exact for the definitions used. It also matches the unit that scientific and programming timing systems rely on internally.