Time Calculator
Add or subtract time, and find the difference between two times.
About the Time Calculator
The AlarmDaddy Time Calculator does two everyday jobs: it adds or subtracts hours and minutes from a start time, and it finds the duration between two times. Use it to work out an end time after a task, a start time before a deadline, or how long a shift or journey lasted.
In add/subtract mode, pick a start time and add or take away hours and minutes — the result rolls correctly past midnight and tells you if it lands on another day. In difference mode, enter two times and read the gap in hours and minutes, with support for spans that cross midnight.
How to use this calculator
- 1Choose Add/Subtract or Difference mode.
- 2For add/subtract: pick a start time and enter hours and minutes to add or take away.
- 3For difference: enter a start time and an end time.
- 4Read the resulting time or the duration.
The formula
Times are converted to minutes since midnight for the arithmetic, then converted back to hours and minutes. Adding time wraps around a 24-hour clock and reports any day rollover; a difference that ends before it starts is treated as spanning midnight.