Time Calculator
Add or subtract hours, minutes, and seconds — for timesheets and media.
How the calculator works
Each duration is converted to total seconds — hours × 3600 plus minutes × 60 plus seconds — and the operation applies to those plain integers: adding is a sum, subtracting a difference that may go negative. The result converts back by dividing: whole hours come from ÷ 3600, the remainder's whole minutes from ÷ 60, and the last seconds stay as the final remainder. Because the result is a duration rather than a time of day, hours are not capped at 23 or 24; a week's work is shown as 40:00:00. Unit totals underneath — say 4.1 hours — are what payroll and billing systems usually expect.
Formula
Result = A op B, converted back to H:MM:SS
Where:
- H, M, S — hours, minutes (0–59) and seconds (0–59) of each duration
- op — add or subtract
- Conversion back: ÷ 3600 for hours, remainder ÷ 60 for minutes
Example
Add 2:45:30 and 1:20:45: in seconds that is 9,930 + 4,845 = 14,775, which reads back as 4:06:15 — or 4.1 hours, or 246.25 minutes. Subtracting instead gives 5,085 seconds = 1:24:45. If you track two work blocks of 6:15:00 and 5:50:00, the weekly card reads 12:05:00 — precisely the figure an invoicing line needs.