Time Calculator
Add and subtract time durations in HH:MM:SS, HH:MM or unit format, with decimal hours, total minutes, total seconds and copyable results.
Add and subtract time durations
The English time calculator SERP is mostly about duration math: add 1:30:00 plus 45 minutes, subtract a break, and keep the result as a duration instead of a clock time.
Durations can be entered as HH:MM:SS, HH:MM, hours only, or unit strings such as 1h 30m 15s.
Duration math, not a clock-time converter
- 36:15:00 means 36 hours and 15 minutes, not a time of day.
- The result can be negative when subtractions exceed additions.
- Decimal hours are shown for payroll-style spreadsheets and estimates.
- Use the duration calculator when the task starts with a start time and end time.
Frequently Asked Questions
Sources and References
- DateMDN Web Docs
- Representing dates and timesMDN Web Docs
- International System of Units: TimeNIST
- ISO 8601 date and time formatISO
- Time Duration Calculatortimeanddate.com
Calculations are based on the listed reference sources. Links open in a new tab.
Related Tools
Calculate duration between a start and end time or between two date-times, with optional break deduction, overnight shifts, decimal hours and night-minute reference.
Calculate the elapsed hours and minutes between two date-times, with total hours, total minutes, seconds, decimal hours, days and 8-hour shift estimates.
Add years, months, weeks, days, hours, minutes and seconds to a start date and time, then see the resulting date-time and total offset.
Subtract years, months, weeks, days, hours, minutes and seconds from a start date and time, then see the resulting past date-time.