raatools/

Time Calculator

Convert between weeks, days, hours, minutes and seconds instantly.

1
Weeks
7
Days
168
Hours
10,080
Minutes
604,800
Seconds
604,800,000
Milliseconds

Quick Facts

How many seconds in a day? 86,400
How many seconds in an hour? 3,600
How many minutes in a day? 1,440
How many hours in a week? 168
How many weeks in a year? 52.143
How many hours in a year? 8,760
How many seconds in a year? 31,536,000
How many minutes in a year? 525,600

What is a time calculator?

A time calculator adds, subtracts, and converts time values. Whether you need to total hours worked on a timesheet, calculate the duration between two timestamps, or convert between hours, minutes, seconds, and other time units, this tool handles all time arithmetic with precision.

Time math is tricky because it uses mixed radix (base-60 for minutes and seconds, base-24 for hours, variable days per month). Adding 2 hours 45 minutes + 3 hours 30 minutes gives 6 hours 15 minutes, not 5 hours 75 minutes. This tool handles these conversions automatically so you do not need to do the mental gymnastics.

How to use this tool

Enter time values in hours, minutes, and seconds format. Choose addition or subtraction. The tool computes the result and displays it in multiple formats: hours:minutes:seconds, decimal hours, total minutes, and total seconds. You can chain multiple operations to total up a list of time entries.

Time unit conversions

  • 1 day = 24 hours = 1,440 minutes = 86,400 seconds.
  • 1 week = 7 days = 168 hours = 10,080 minutes.
  • 1 year = 365 days (or 366 in a leap year) = 8,760 hours.
  • 1 hour = 60 minutes = 3,600 seconds. Decimal hours: 1.5 hours = 1 hour 30 minutes.

Timesheet calculations

To calculate hours worked: subtract the start time from the end time, then subtract any break time. For example: started at 8:30 AM, ended at 5:15 PM, with a 45-minute lunch break. Total: 8 hours 45 minutes minus 45 minutes = 8 hours exactly. This tool lets you add multiple time entries to calculate weekly totals for payroll or invoicing.

Frequently asked questions

How do I convert decimal hours to hours and minutes?

Multiply the decimal part by 60. For example, 3.75 hours: the whole number is 3 hours, and 0.75 * 60 = 45 minutes, so 3.75 hours = 3 hours 45 minutes. Going the other way: 2 hours 20 minutes = 2 + 20/60 = 2.333 decimal hours. This tool performs these conversions automatically.

Does this tool handle crossing midnight?

Yes. If you subtract an earlier time from a later time that crosses midnight (like 11:00 PM to 2:00 AM), the tool correctly calculates the duration as 3 hours. It assumes the second time is on the following day when it is earlier than the first time.