Add and subtract time in hours, minutes, and seconds
Time calculation involves adding or subtracting time values in hours, minutes, and seconds. Unlike decimal arithmetic, time uses a base-60 system for minutes and seconds, requiring special handling when values exceed 59 or become negative. This calculator handles all the complexity of time arithmetic, including carrying over between units and managing time that crosses midnight.
When adding time values, the process follows these steps:
For example, adding 2:45:30 + 1:30:45 results in 4:16:15 (4 hours, 16 minutes, 15 seconds).
When subtracting time values, the process involves borrowing when necessary:
For example, subtracting 5:20:15 - 2:45:30 results in 2:34:45 (2 hours, 34 minutes, 45 seconds).
Calculate total work hours by adding time entries throughout the day or week. Useful for timesheets and payroll.
Add up task durations to estimate project completion times or calculate remaining time for deadlines.
Calculate total travel time by adding flight durations, layovers, and ground transportation times.
Add cooking times for multiple dishes to plan when to start each item for simultaneous completion.
Track total workout time by adding durations of different exercises or training sessions.
Calculate event end times by adding duration to start time, or determine how much time remains.
| Format | Description | Example |
|---|---|---|
| 24-Hour Format | Uses 0-23 for hours, no AM/PM needed | 14:30:00 (2:30 PM) |
| 12-Hour Format | Uses 1-12 for hours with AM/PM designation | 2:30:00 PM |
| Decimal Hours | Represents time as decimal (30 min = 0.5 hours) | 2.5 hours |
| Total Seconds | Converts entire duration to seconds | 9,000 seconds |
Stick to either 12-hour or 24-hour format throughout your calculations to avoid confusion and errors.
When calculating time differences that span midnight, ensure you account for the day change (e.g., 11:00 PM to 2:00 AM is 3 hours, not -21 hours).
For multiple time additions or subtractions, break them into smaller steps and verify each intermediate result.
When working with times from different locations, convert to a common time zone before performing calculations.
Depending on your use case, decide whether to round to the nearest minute, second, or keep full precision.
Scenario: An employee works from 8:30 AM to 5:15 PM with a 45-minute lunch break.
• Total time: 5:15 PM - 8:30 AM = 8 hours 45 minutes
• Subtract lunch: 8:45:00 - 0:45:00 = 8:00:00
• Result: 8 hours of work time
Scenario: Flight 1 is 6:30:00, layover is 2:15:00, Flight 2 is 8:45:00.
• Add Flight 1 + Layover: 6:30:00 + 2:15:00 = 8:45:00
• Add Flight 2: 8:45:00 + 8:45:00 = 17:30:00
• Result: 17 hours 30 minutes total travel time
Scenario: Task A takes 2:30:00, Task B takes 1:45:00, Task C takes 3:15:00.
• Add Task A + Task B: 2:30:00 + 1:45:00 = 4:15:00
• Add Task C: 4:15:00 + 3:15:00 = 7:30:00
• Result: 7 hours 30 minutes total project time
Scenario: Night shift starts at 10:00 PM and ends at 6:30 AM.
• Time to midnight: 24:00:00 - 22:00:00 = 2:00:00
• Time after midnight: 6:30:00 - 0:00:00 = 6:30:00
• Total: 2:00:00 + 6:30:00 = 8:30:00
• Result: 8 hours 30 minutes shift duration
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