Time Calculator
Perform various time-related calculations including adding and subtracting time, finding the duration between two times, and converting between different time units.
Time Unit Conversions
| Unit | Equivalent |
|---|---|
| 1 Minute | 60 Seconds |
| 1 Hour | 60 Minutes / 3,600 Seconds |
| 1 Day | 24 Hours / 1,440 Minutes |
| 1 Week | 7 Days / 168 Hours |
| 1 Year (Common) | 365 Days / 8,760 Hours |
Why Use a Time Calculator?
Time calculations can be tricky because time doesn't follow a decimal system. Instead of base-10, time uses base-60 (sexagesimal) for minutes and seconds, and base-24 for hours in a day. This makes manual addition and subtraction prone to errors, especially when "carrying over" values.
Our calculator handles these complexities for you, whether you're tracking work hours, planning a schedule, or converting units for a scientific project.
12-Hour vs. 24-Hour Time
The 12-hour clock divides the day into two periods: AM (ante meridiem) and PM (post meridiem). The 24-hour clock (often called military time) runs from 00:00 to 23:59.
- To convert 12h to 24h: For PM times (except 12 PM), add 12 to the hours. For 12 AM, change hours to 00.
- To convert 24h to 12h: For hours 13-23, subtract 12 and add PM. For hour 00, change to 12 and add AM. For hour 12, just add PM.
Limitations & Considerations
- Time Zones: This calculator does not account for time zone differences or Daylight Saving Time changes.
- Leap Seconds: Extremely precise scientific calculations may need to account for leap seconds, which are ignored here.
- Calendar Variations: Calculations involving months and years are based on averages (30.44 days per month, 365.25 days per year).
Time Formulas
Decimal Hours: Hours + (Minutes / 60) + (Seconds / 3600)
Time Difference: |Time 2 - Time 1| in seconds, then converted back to H:M:S.
Frequently Asked Questions
Add the minutes first: 45 + 30 = 75 minutes. Since 75 minutes is 1 hour and 15 minutes, you carry the 1 hour over. Then add the hours: 1 + 2 + 1 (carried) = 4 hours. Total: 4 hours and 15 minutes.
To convert decimal hours to minutes, multiply by 60. 0.5 × 60 = 30 minutes.
There are 86,400 seconds in a standard 24-hour day (24 × 60 × 60).
Military time is another name for the 24-hour clock system. It is used to avoid confusion between AM and PM, especially in emergency services, aviation, and the military.
For calculations involving specific dates, we recommend using our Age Calculator or a dedicated Date Duration tool, as months vary in length.