Time Calculator
Add or subtract a duration from a clock time. Use 12-hour or 24-hour time and see clearly when the result falls on another day.
How to calculate a time of day
Choose a starting clock time, select add or subtract, and enter a duration in hours and minutes. The result identifies whether the calculation stays on the same day or crosses midnight.
Time calculation example
Starting at 8:30 AM and adding 2 hours 45 minutes gives 11:15 AM. Starting at 11:30 PM and adding 2 hours gives 1:30 AM on the next day.
Time calculator versus hours calculator
A time calculator produces a clock time. An hours calculator totals durations without a time of day. If you need a workday finish time that includes a break, use the clock out calculator.
Frequently asked questions
Does subtracting time support the previous day?
Yes. If the duration reaches before midnight, the result is marked as the previous day.
Can I use 24-hour time?
Yes. Switch the calculator to 24-hour mode to enter and view military-style clock times.