What does this time calculator do?
It adds or subtracts durations, moves a starting date and time, and evaluates expressions containing days, hours, minutes and seconds.
What happens if I leave a duration field blank?
Blank day, hour, minute and second duration fields count as zero. This does not mean you can omit the starting date required by Date mode.
Can I enter more than 60 minutes?
The homepage explains that values such as 90 minutes are carried into hours in the result. Ninety minutes becomes 1 hour and 30 minutes.
Can the result be negative?
Yes. Subtracting a longer duration from a shorter one gives a negative duration. For example, 30 minutes minus 1 hour equals −30 minutes.
Which expression units can I use?
Use d for days, h for hours, m for minutes and s for seconds. Put a unit after each number and use plus or minus between groups, such as 2h + 30m – 15s.
Can I enter decimal hours?
Yes, decimals are documented for Expression mode. For example, 1.5h means 1 hour 30 minutes. This does not establish support for decimal inputs in every other field.
Is one day always 24 hours?
In a duration or expression, one day is 24 hours. In Date mode, adding one day moves the calendar date and keeps the clock time. A daylight saving transition can make that calendar interval shorter or longer than 24 elapsed hours.
Does Date mode include leap years?
The homepage states that date shifts follow the Gregorian calendar, including leap days and different month lengths. For example, 28 February 2024 plus one calendar day is 29 February 2024.
Which time zone does the date calculator use?
It uses your device’s local clock settings. Check those settings before calculating a date. The retrieved interface does not include a time-zone conversion selector.
Can I calculate work hours after a break?
You can subtract a break from a known shift duration. For example, 8 hours 30 minutes minus a 30-minute break equals 8 hours. This does not apply payroll rules, overtime thresholds or rounding policies.
Why does the calculator need JavaScript?
The page requires JavaScript for calculations in your browser. Enable JavaScript if inputs are visible but calculations are unavailable. Contact us if the problem continues.
How do I report an unexpected result?
Visit Contact and send the mode, inputs, actual result and expected result. For date issues, include the device time zone. See our usage guide for worked examples.