Time Calculator
Use this calculator to add or subtract days, hours, minutes, and seconds from a starting time. You can also find the exact time span between two clock times.
Add or Subtract Time
Enter a start time, choose an operation, and add a duration.
Time Duration Calculator
Calculate elapsed time between two date and time values.
Time Unit Converter
Convert a duration into total days, hours, minutes, and seconds.
Hours Calculator
Find worked hours from a start time, end time, and break length.
Time Card Calculator
Enter daily clock-in, clock-out, and break time to total a weekly timesheet.
Date Calculator
Count days between dates or add years, months, weeks, and days to a date.
Month, Age, and Birthday Calculators
Compute calendar months, precise age, and the next birthday countdown.
Weeks, Days, and Hours From Now
Find a future or past date/time from today.
Time to Decimal and Decimal to Time
Convert clock-style time into decimal payroll hours and back again.
Military Time Converter
Convert 24-hour military time to standard time and standard time to military time.
Overtime Calculator
Calculate regular pay, overtime pay, and time-and-a-half totals.
| Pay type | Hourly rate | Hours | Total |
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How to use the calculator
Pick a starting date and clock time, enter the amount of time you want to add or subtract, then press calculate. The result keeps the full date so overnight and multi-day calculations are handled correctly.
For elapsed time, enter the beginning and ending times. If the ending value is earlier than the beginning value, the calculator reports the absolute duration and shows which direction the interval runs.
Common examples
Frequently Asked Questions
Can this calculator handle dates?
Yes. Date inputs are included so calculations can pass midnight, move across months, and cover long durations.
Does it use my local time zone?
The calculator uses your browser's local time zone for displaying dates and times.
Can I use it for work hours?
Yes, it is useful for schedule planning, shift length checks, study timers, travel intervals, and similar everyday time math.