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Time Unit Converter

Convert any time duration between milliseconds, seconds, minutes, hours, days, weeks, months, and years.

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How to use Time Converter

  1. Enter a duration in its row — milliseconds, seconds, minutes, hours, days, weeks, months, or years.
  2. The other rows recalculate, with months held at 30 days and years at 365 for estimates.
  3. To work back from, say, hours, type the number of hours into that row instead.
  4. The month and year rows are averages, not calendar dates — if your answer has to land on a real date or respect leap years, take it to the age calculator instead of trusting the 30/365 figures here.

Time converter: milliseconds to years

This converter translates any duration across eight units — milliseconds, seconds, minutes, hours, days, weeks, months, and years. Enter a duration in one row and the others are recalculated from it. The exact relationships appear below, along with a note on where months and years are only approximate so you know when to reach for a calendar tool instead.

The exact time relationships

  • 1 second = 1,000 milliseconds
  • 1 minute = 60 seconds
  • 1 hour = 60 minutes = 3,600 seconds
  • 1 day = 24 hours = 86,400 seconds
  • 1 week = 7 days = 604,800 seconds
  • 1 month (30-day average) = 2,592,000 seconds
  • 1 year (365 days) = 31,536,000 seconds

Where the conversion is exact — and where it is not

Milliseconds through weeks are exact: those units are defined by fixed counts of seconds. Months and years are the only approximations. A real month is 28, 29, 30, or 31 days, and a real year averages 365.2425 days because of leap years. This tool uses round 30-day months and 365-day years for fast estimates. For anything that must land on a real calendar date, use the age calculator instead.

Everyday duration conversions

The most frequent swaps are minutes to hours (divide by 60), hours to days (divide by 24), and seconds to minutes (divide by 60). A common workplace example: a 2,400-minute monthly commute is 40 hours — a full extra work week spent traveling. Seeing the same duration in a different unit often reframes how big or small it really is.

Developer and timestamp use

Programmers convert milliseconds constantly. Unix timestamps and JavaScript's Date.now() count milliseconds since 1 January 1970, so dividing by 1,000 gives seconds, by 86,400,000 gives days. Network and animation timeouts are also in milliseconds — knowing that 250 ms is a quarter-second helps you reason about responsiveness.

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Frequently asked questions

How many seconds are in a day?
Exactly 86,400 seconds (24 hours × 60 minutes × 60 seconds). A week is 604,800 seconds, and a 365-day year is 31,536,000 seconds.
How do I convert minutes to hours?
Divide minutes by 60. So 150 minutes = 2.5 hours. To go from hours to minutes, multiply by 60.
Why is a month treated as 30 days here?
Calendar months range from 28 to 31 days, so there is no single exact value. This converter uses 30 days as a practical average for quick estimates. For date-accurate math that respects each month and leap years, use a date difference calculator.
How long is a year in this tool?
A year is taken as 365 days (31,536,000 seconds). The true mean solar year is about 365.2425 days, which is why the calendar adds a leap day every four years. For exact calendar arithmetic, use a dedicated age or date tool.
How do I convert milliseconds to seconds?
Divide by 1,000. A 500 ms web timeout is 0.5 seconds; 1,500 ms is 1.5 seconds. Developers often need this when reading timestamps, which are usually in milliseconds since 1970.
How many hours are in a work week?
A standard 40-hour work week is 5 days of 8 hours. In total seconds that is 144,000. A full 7-day calendar week is 168 hours.
How do I convert a duration like 90 minutes to hours and minutes?
Divide by 60 for the whole hours (1), then the remainder is the leftover minutes (30): 90 minutes = 1 hour 30 minutes. This converter gives the decimal form (1.5 hours); split off the whole part to get hours-and-minutes.

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