Perform precise time arithmetic for scheduling, planning, and duration management tasks.
Overview
Time arithmetic is useful for schedules, shift planning, and project timing.
This calculator handles adding and subtracting durations with carry and borrow rules.
Use consistent format to avoid AM/PM or rollover confusion.
Steps
Select time addition or subtraction.
Input clock time or duration baseline.
Provide hours, minutes, and seconds to add or subtract.
Apply carry/borrow logic across units.
Identify if result crosses midnight boundaries.
Math
Total Seconds = h*3600 + m*60 + s; apply +/- then reconvert
Converting to total seconds simplifies arithmetic before converting back to time format.
Worked cases
Convert and sum
13:15
Borrow minutes where needed
13:25
Add and rollover
02:15 next day
Why use this
Questions