Time Arithmetic Calculator
Enter two durations (A and B) as days, hours, minutes, and seconds — then add or subtract (A − B). Useful for rosters, travel, or study blocks — not for high-precision physics.
Durations
Result
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Notes
Negative totals from A − B mean B is longer than A — we still show the absolute span. For clock times on a calendar, combine with our date difference tool.
Frequently asked questions
How do addition and subtraction work?
Addition sums the two durations. Subtraction computes A minus B; if B is longer, we show the absolute span with a minus sign on the main line, matching the note in the help section.
What does the total seconds line mean?
It is the same result expressed as a single integer of seconds for quick comparisons or copying into spreadsheets.
Can I enter fractional seconds or minutes?
The inputs accept whole numbers in this UI; fractional time would need scaling (e.g. enter extra seconds) or use another tool.
Is this the same as adding clock times on a calendar?
No—this tool only adds durations. For midnight-to-midnight spans between calendar dates, use the date difference calculator.
Are negative results errors?
They mean duration B is longer than A when subtracting; we still display the magnitude so you can see how much longer.
Is my data uploaded?
No. All math runs in your browser with no signup.