Base-60 arithmetic, handled for you
Add or subtract durations in hours and minutes without decimal confusion. Because 1.5 hours is 1:30, not 1:50.
Time is the one everyday unit that is not decimal. Sixty minutes to the hour means 45 + 45 gives 1:30, not 90-something, and mental arithmetic goes wrong fast.
This handles carrying across the hour boundary, which is where most manual timesheet errors come from.
The total duration in hours and minutes Addition and subtraction of time spans Correct carrying when minutes pass 60 Works with durations rather than clock times, so results can exceed 24 hours. Decimal hours and clock notation are different: 2.75 hours is 2:45. How do I convert decimal hours to minutes? Multiply the fraction by 60. 0.25 hours is 15 minutes, 0.75 is 45. Payroll systems use decimals; clocks do not.
What is 1.5 hours in hours and minutes? 1 hour 30 minutes. Reading it as 1:50 is the classic mistake, and it inflates a timesheet by twenty minutes.
Can the total go past 24 hours? Yes. These are durations, not clock readings, so 30:00 is a valid answer for a long project total.
Does it handle seconds? It works in hours and minutes, which covers timesheets and scheduling. Second-level precision belongs to a stopwatch.
Worked example Three tasks in an afternoon
Input: 1:45 + 2:30 + 0:50
Output: 5:05
Note: The minutes total 125, which carries as two hours and five minutes. Adding the columns separately is exactly where people slip.
