Time Calculator
Add or subtract time durations, or calculate a new date and time by applying a duration to a starting date.
Add and Subtract Time Calculator
Add or Subtract Time from a Date Calculator
How to Use This Time Calculator
Use the first calculator to add or subtract two time durations. Enter values for days, hours, minutes, and seconds in both rows, choose an operation, and click Calculate.
Use the second calculator to add or subtract a duration from a specific starting date and time. Select the date, enter the time, choose Add or Subtract, then enter the duration values.
Time Calculation Formulas
Total seconds for a duration: (days × 86,400) + (hours × 3,600) + (minutes × 60) + seconds
Duration result: Duration A ± Duration B
Date and time result: Start date and time ± duration
Normalized format: Convert the final total seconds back into days, hours, minutes, and seconds.
What This Tool Can Calculate
This tool can calculate time differences and time totals using days, hours, minutes, and seconds. It can also calculate a future or past date and time by adding or subtracting a duration from a selected starting point.
Example Calculations
Duration example: 2 days, 34 hours, 37 minutes, 65 seconds + 1 day, 23 hours, 32 minutes, 34 seconds = 5 days, 10 hours, 10 minutes, 39 seconds
Date example: April 19, 2026, 2:29:50 PM + 1 day, 25 hours, 45 minutes, 64 seconds = April 21, 2026, 4:15:54 PM
References
For official time information and standards, see:
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