Add or Subtract Time Calculator
Easily add or subtract two time durations. Perfect for calculating total hours, project lengths, or shifts.
Time 1 (Starting Duration)
Time 2 (Duration to )
*Note: For calculation purposes, 1 Month is considered 30 Days.
About Time Calculator
Unlike regular numbers which use a base-10 system, time calculations are much more complex. We use a base-60 system for minutes and hours, and a base-24 system for days. This makes manual addition and subtraction prone to errors.
Our free online Time Calculator simplifies this. By automatically handling all the complex "borrowing" and "carrying over" of numbers, it gives you exact duration calculations for payrolls, logbooks, flight times, and project management.
How to Use
- 1 Enter your initial duration in the Time 1 section (Left). Leave boxes blank or 0 if they don't apply.
- 2 Click the big + (Add) or - (Subtract) button in the middle to select your action.
- 3 Enter the duration you want to add or subtract in the Time 2 section (Right).
- 4 The final calculation will appear in the result box below instantly.
Important Formulas & How to Calculate Manually
Adding Time Manually
To add time, add corresponding units together. If a unit exceeds its maximum limit, "carry over" to the next larger unit.
- Minutes: If total is 60 or more, subtract 60 and add 1 to Hours.
- Hours: If total is 24 or more, subtract 24 and add 1 to Days.
- Days: If total is 30 or more, subtract 30 and add 1 to Months.
- Months: If total is 12 or more, subtract 12 and add 1 to Years.
Subtracting Time Manually
To subtract time, if the bottom number is larger than the top number, you must "borrow" from the next larger unit.
- Minutes: Borrow 1 Hour. Add 60 to your Minutes.
- Hours: Borrow 1 Day. Add 24 to your Hours.
- Days: Borrow 1 Month. Add 30 to your Days.
- Months: Borrow 1 Year. Add 12 to your Months.
1 Year = 12 Months | 1 Month = 30 Days | 1 Day = 24 Hours | 1 Hour = 60 Minutes