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Time Unit Converter.

Convert between milliseconds, seconds, minutes, hours, days, weeks, months and years — plus HH:MM to total minutes and decimal hours.

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Converted value: 60

Converted value

60.000000

Breakdown

Total seconds3,600

HH:MM as minutes and decimal hours

Total minutes
450
Decimal hours
7.5

Note: months and years are approximations. 1 month = 30.436875 days and 1 year = 365.2425 days, the Gregorian calendar mean. All other units are exact.

How to Use

Months and years are not fixed lengths. This converter uses the Gregorian mean: 1 year = 365.2425 days (31,556,952 seconds) and 1 month = one twelfth of that = 30.436875 days (2,629,746 seconds). Milliseconds through weeks are exact.

FAQs

How many seconds are in an hour?

There are 3,600 seconds in an hour, 60 in a minute, 86,400 in a day and 604,800 in a week. These conversions are exact.

How many days are in a month for this converter?

It uses the Gregorian mean of 30.436875 days (2,629,746 seconds), which is one twelfth of an average year. Real calendar months range from 28 to 31 days, so treat any month result as an approximation.

How many days are in a year?

This converter uses 365.2425 days (31,556,952 seconds), the Gregorian calendar's long-run average that accounts for leap years and the skipped century leap years. An individual year is 365 or 366 days.

How do I turn HH:MM into decimal hours?

Divide the minutes by 60 and add them to the hours: 7:30 is 7 + 30/60 = 7.5 decimal hours. The secondary readout on this page does it for you, and also gives the total minutes (450), which payroll systems often need.

Which units are exact and which are approximate?

Milliseconds, seconds, minutes, hours, days and weeks are exact fixed ratios. Only months and years are averages, because calendar months and leap years vary in length.

Cite this calculator

Canonical URL: https://mathify.one/zh/conversion/time

Cite as: Mathify. (2026). 时间单位换算器. https://mathify.one/zh/conversion/time

Use Cases

Project Time Estimation

Convert durations between units to plan tasks, track deadlines, or estimate total time in hours or minutes.

Example: Convert 3 days to hours to see it's 72 hours.

Payroll and Billing

Convert HH:MM timesheets to decimal hours for accurate payroll calculations or client billing.

Example: Convert 8:45 to 8.75 decimal hours.

Frequently Asked Questions

How do I convert HH:MM to total minutes?
Enter hours and minutes in the HH:MM format. The converter multiplies hours by 60 and adds the minutes to give you the total minutes. For example, 1:30 becomes 90 minutes.
What is decimal hours and how is it calculated?
Decimal hours represent time as a fraction of an hour. For HH:MM, divide minutes by 60 and add to hours. For instance, 1:30 is 1.5 decimal hours. This is useful for payroll or time tracking.
Can I convert between any time units like milliseconds to years?
Yes, the converter supports milliseconds, seconds, minutes, hours, days, weeks, months, and years. Enter a value in one unit and select the target unit to get the equivalent.

Tips & Common Mistakes

Tips

  • When converting months, note that the converter uses an average month length (30.44 days) for consistency.
  • For HH:MM input, ensure you use the colon separator (e.g., 2:30) to get correct results.
  • Double-check your input units and target units to avoid conversion errors.
  • Use the converter for quick estimates; for precise scientific calculations, consider leap years and exact month lengths.

Common Mistakes to Avoid

  • Forgetting to select the correct target unit, leading to wrong conversions.
  • Entering HH:MM without the colon, e.g., '230' instead of '2:30', which may be interpreted as 230 minutes.
  • Assuming months are exactly 30 days; the converter uses an average, so results may differ from calendar months.

Last updated: August 13, 2026