Hours Calculator
Calculate time duration between two times, track work hours, or add/subtract hours and minutes from any time.
1
Calculation Mode
2
Start Time
:
9:00 AM
3
End Time
:
5:00 PM
Total Duration
8 hr
480
Total Minutes
8.00
Decimal Hours
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What is Time Calculation?
Time calculation involves computing differences between times, converting time formats, or adding/subtracting durations from clock times.
Common operations include:
- Finding hours between two times
- Adding hours and minutes to a time
- Converting between 12-hour and 24-hour formats
Calculating Hours Between Times
To find the duration between two times:
Example: From 9:00 AM to 5:30 PM
- Convert to 24-hour format: 9:00 and 17:30
- Subtract: 17:30 - 9:00 = 8 hours 30 minutes
Crossing Midnight
When times cross midnight, add 24 hours to the end time:
Example: From 10:00 PM to 6:00 AM
- Convert: 22:00 to 6:00
- Add 24 to end time: 6:00 + 24:00 = 30:00
- Subtract: 30:00 - 22:00 = 8 hours
Time Format Conversion
12-Hour to 24-Hour
| 12-Hour | 24-Hour |
|---|---|
| 12:00 AM | 00:00 |
| 1:00 AM | 01:00 |
| 12:00 PM | 12:00 |
| 1:00 PM | 13:00 |
| 11:00 PM | 23:00 |
Rules:
- AM times: Keep as is (except 12 AM = 00:00)
- PM times: Add 12 (except 12 PM stays 12:00)
Working with Breaks
When calculating work hours, subtract break time:
Example:
- Start: 8:00 AM
- End: 5:00 PM
- Break: 1 hour
Total work time = 9 hours - 1 hour = 8 hours
Adding Time to a Clock
Example: Add 3 hours 45 minutes to 10:30 AM
- Add hours: 10:30 + 3:00 = 13:30 (1:30 PM)
- Add minutes: 13:30 + 0:45 = 14:15 (2:15 PM)
Handling Overflow
When minutes exceed 60:
- Add 4:50 to 9:30 AM
- 9:30 + 4:50 = 13:80
- 80 minutes = 1 hour 20 minutes
- Final: 14:20 (2:20 PM)
Decimal Hours
Some systems use decimal hours instead of hours:minutes.
| Hours:Minutes | Decimal Hours |
|---|---|
| 0:15 | 0.25 |
| 0:30 | 0.50 |
| 0:45 | 0.75 |
| 1:30 | 1.50 |
| 2:15 | 2.25 |
Conversion formula:
- To decimal: hours + (minutes / 60)
- To minutes: (decimal - whole hours) × 60
Common Use Cases
Work Hours Tracking
- Calculate daily hours for timesheets
- Track overtime (hours beyond standard workday)
Scheduling
- Determine meeting end times
- Calculate travel arrival times
Payroll
- Convert time worked to decimal hours for pay calculations
- Calculate overtime pay rates
Time Zones
When calculating across time zones:
- Convert both times to the same zone (or UTC)
- Perform the calculation
- Convert result back if needed
Tips for Accurate Time Calculation
- Be consistent with AM/PM vs 24-hour format
- Account for date changes when crossing midnight
- Double-check break deductions
- Use decimal hours for precise payroll calculations
- Consider DST (Daylight Saving Time) for date-spanning calculations