Time Calculator
Time Conversions
Related Calculators
Understanding Time Calculations
Common Uses
Work & Productivity
- • Calculate total hours worked
- • Track project time
- • Sum multiple time entries
- • Calculate overtime
Scheduling
- • Calculate arrival times
- • Plan meeting durations
- • Time zone conversions
- • Travel time planning
Sports & Fitness
- • Sum lap times
- • Calculate pace
- • Track workout duration
- • Split time calculations
Media & Production
- • Video/audio length
- • Episode runtimes
- • Playlist duration
- • Recording time
Time Arithmetic
Time uses a base-60 system for seconds and minutes, and base-24 for hours. This requires carrying and borrowing differently than regular math:
Adding Time
2:45:30
+ 1:30:45
= 4:16:15
30 + 45 = 75 seconds = 1 min 15 sec
45 + 30 + 1 = 76 minutes = 1 hr 16 min
Subtracting Time
5:15:20
- 2:45:40
= 2:29:40
Need to borrow from minutes and hours
20 - 40 → 80 - 40 = 40 seconds
Decimal Time Conversions
Converting time to decimal format is useful for calculations and billing:
| Time Format | Decimal Hours | Decimal Minutes |
|---|---|---|
| 0:15 | 0.25 hours | 15 minutes |
| 0:30 | 0.50 hours | 30 minutes |
| 0:45 | 0.75 hours | 45 minutes |
| 1:30 | 1.50 hours | 90 minutes |
| 2:15 | 2.25 hours | 135 minutes |
Conversion Formulas
Decimal Hours = Hours + (Minutes / 60) + (Seconds / 3600)
Total Minutes = (Hours × 60) + Minutes + (Seconds / 60)
Total Seconds = (Hours × 3600) + (Minutes × 60) + Seconds
Time Zones and UTC
When working across time zones, times are often referenced to UTC (Coordinated Universal Time):
- EST (Eastern): UTC - 5 hours
- CST (Central): UTC - 6 hours
- MST (Mountain): UTC - 7 hours
- PST (Pacific): UTC - 8 hours
Note on 24-Hour vs 12-Hour Time
This calculator uses duration (total hours:minutes:seconds) rather than clock time. For clock time calculations involving AM/PM or specific times of day, consider the context of your calculation. For example, 2:00 PM = 14:00 in 24-hour format.
Frequently Asked Questions
How do I add hours and minutes together?
Add hours and minutes separately, then convert excess minutes to hours. For 2:45 + 1:30: hours = 2+1=3, minutes = 45+30=75. Since 75 min = 1 hr 15 min, total = 4:15.
How do I convert time to decimal hours?
Divide minutes by 60 and add to hours. For 2 hours 30 minutes: 30/60 = 0.5, so 2:30 = 2.5 decimal hours. Common conversions: :15 = 0.25, :30 = 0.50, :45 = 0.75.
How do I calculate elapsed time between two times?
Subtract start from end time. If end is earlier (crosses midnight), add 24 hours first. From 10:30 PM to 2:15 AM: (2:15 + 24:00) - 22:30 = 26:15 - 22:30 = 3:45 elapsed.
Why does time use base 60?
Ancient Babylonians used base 60 (sexagesimal) because 60 is highly divisible (by 1,2,3,4,5,6,10,12,15,20,30). This makes it easy to divide an hour into halves, thirds, quarters, fifths, sixths, and twelfths.