Time Calculator
Add or subtract durations in hours, minutes, and seconds.
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How to Use the Free Online Time Calculator
Effortlessly add and subtract time intervals in hours, minutes, and seconds without the confusion of base-60 conversions.
1. Enter Initial Time
Input the starting hours, minutes, and seconds for your first time interval (e.g., your shift start time or media duration).
2. Choose Operation
Select Add to sum cumulative time periods together, or Subtract to find elapsed time or countdown differences.
3. Instant Exact Result
Get clean, standardized duration totals with automatic 60-second and 60-minute carryovers and borrowings applied.
Why Time Math is Tricky (The Base-60 Rule)
Unlike ordinary math which operates in base-10, time operates in sexagesimal (base-60):
- Adding: 45 minutes + 30 minutes is not 75 minutes, but 1 hour and 15 minutes.
- Subtracting: If you subtract 40 minutes from 1 hour 10 minutes, you must borrow 60 minutes from the hour, turning it into 70 minutes − 40 minutes = 30 minutes.
Everyday Applications
- Work & Payroll: Accurately calculate weekly hourly totals, overtime, and break deductions for timesheets.
- Audio & Video Editing: Calculate exact video runtime, podcast track lengths, and clip cuts.
- Fitness & Athletics: Add split times, running lap intervals, and workout rests.
- Travel & Navigation: Calculate total flight durations, layovers, and road trip ETA adjustments.
Frequently Asked Questions
Common questions about adding and subtracting time durations.
Time uses a sexagesimal (base-60) system rather than a base-10 decimal system. When adding, 60 seconds carry over as 1 minute, and 60 minutes carry over as 1 hour. When subtracting, if minutes or seconds are negative, you borrow 60 units from the larger time unit.
Subtract your clock-in time from your clock-out time to determine daily shift duration. You can then use the addition mode to sum daily work hours across the entire week or pay period.
Multiply the decimal portion by 60. For example, 7.5 hours equals 7 hours and (0.5 × 60) = 30 minutes. Similarly, 4.25 hours equals 4 hours and 15 minutes.
Common applications include summing work timesheet hours, calculating video and audio editing track lengths, tracking athletic workout intervals, measuring flight layovers, and setting cooking timers.
In time duration mathematics, time cannot be negative. If subtracting results in a negative duration, ensure the earlier start time is subtracted from the later completion time.