Time Calculator
This free time calculator answers two common questions: how much time elapses between two clock times, including a decimal hours figure for timesheets and payroll, and what time you get by adding or subtracting hours and minutes from a time. Nothing you enter is sent anywhere or stored.
How to Use It
- Time Duration Between Two Times: enter a start and end time, and check "Ends the next day" for an overnight span.
- Add or Subtract Time: pick a start time, choose Add or Subtract, and enter the hours and minutes to apply.
- Both update instantly as you change any field.
How It Works
The duration calculation is plain clock time arithmetic: it subtracts the start time from the end time in minutes, then splits the result back into hours and minutes. For an overnight span, checking "Ends the next day" adds a full 24 hours before splitting, so a shift from 10:00 PM to 6:00 AM correctly comes out to 8 hours rather than a negative number. Alongside the hours and minutes figure, the result also shows the same duration as decimal hours, since payroll and timesheet calculations are usually done against a decimal figure rather than a clock time. Thirty minutes is half an hour, so it becomes .50, not .30.
The add/subtract calculation adds or subtracts a hours and minutes duration from a start time and reports the result, noting whether it landed on the next day, the previous day, or (for a duration longer than 24 hours) further out than that. Adding 2 hours 45 minutes to 11:30 PM lands on 2:15 AM the next day, and subtracting 3 hours from 1:00 AM lands on 10:00 PM the previous day.
This tool works with times of day only. It has no calendar date attached and does no time zone conversion, both times are assumed to be in the same time zone. Everything runs client-side in your browser. Nothing you enter is sent anywhere or stored.
Frequently Asked Questions
How do decimal hours work, and why does it matter for payroll?
Timesheets and hourly pay are usually calculated against a decimal figure, not a clock time, so 8 hours and 30 minutes needs to become 8.50, not 8.30. This tool converts the minutes portion for you: 30 minutes is half an hour, so it becomes .50, not .30. Multiplying decimal hours by an hourly rate gives the correct pay for a shift; multiplying 8.30 by an hourly rate would not.
How do I calculate an overnight shift that crosses midnight?
Check the "Ends the next day" box in the Time Duration panel. For example, a shift from 10:00 PM to 6:00 AM checked as ending the next day comes out to 8 hours, the same as any other 8 hour shift. Without checking that box, the end time would appear to be earlier than the start time, which the tool flags as an error rather than guessing what was meant.
How is this different from the Date Calculator?
The Date Calculator works in whole calendar days: how many days are between two dates, or what date you land on after adding or subtracting days, weeks, months, or years. It has no concept of a time of day. This tool is the reverse, pure clock time arithmetic (hours and minutes within a day), with no calendar date involved at all. If you need to know the date some number of days from now, the Date Calculator is the right tool. For anything involving a specific time of day, this one is.
Does this tool convert between time zones?
No. Both times you enter are treated as being in the same time zone, whatever you have in mind, and the tool never asks which one. If you need to find a time that works across multiple time zones, use the Time Zone Meeting Planner instead.
What happens if I add more than 24 hours to a time?
The result rolls over correctly rather than being capped at 24 hours. Adding 25 hours to 8:00 AM lands on 9:00 AM the next day, and the result notes which day it falls on so it is never ambiguous.
Can the Start Time and End Time be the same?
Yes, and it is not treated as an error. With "Ends the next day" unchecked, the same start and end time means zero elapsed time. With it checked, it means a full 24 hours elapsed.
Can I subtract time instead of adding it?
Yes, use the Add/Subtract toggle in the "Add or Subtract Time" panel. Subtracting can land on the previous day, which the result also notes, for example subtracting 3 hours from 1:00 AM lands on 10:00 PM the previous day.