Time Duration Calculator
Add or subtract seconds from a duration and convert the result to decimal hours.
Your result
EVERYDAYEnter your values and select calculate.
On this page How it works & practical examples
How to use the Time Duration Calculator
Enter a duration rather than a time of day. Minutes and seconds must be between 0 and 59; larger amounts belong in hours or the adjustment field. Decimal seconds are allowed for the adjustment. The result normalizes the duration into hours, minutes and seconds, and also shows its total seconds and decimal-hour form.
The calculation
Worked example
1 hour 30 minutes plus 900 seconds is 1 hour 45 minutes, or 1.75 decimal hours. Subtracting 7,200 seconds from 1 hour gives a duration of −1 hour.
Assumptions and limits
This calculation does not cross calendar dates or interpret time zones. The difference between 1:30 AM and 3:30 AM on a daylight-saving transition may not be two elapsed hours, which is outside this duration model. Negative output is a signed duration, with the sign applying to the entire quantity. Decimal hours must not be confused with hours-and-minutes notation.
Common questions
Is 1.30 hours the same as 1 hour 30 minutes?
No. 1.30 decimal hours is 1 hour 18 minutes. One hour 30 minutes is 1.5 decimal hours.
How can I add 90 minutes?
Enter 5,400 seconds in the adjustment field, or represent the starting duration as 1 hour 30 minutes.