About the Time Duration Calculator
Calculating elapsed time between two clock times seems straightforward until the math involves crossing the hour or minute boundary — for example, figuring out the duration from 9:45 AM to 2:15 PM by hand is a common source of small errors.
This tool converts both times to total minutes, calculates the difference, and also converts the result into decimal hours (e.g., 7 hours 30 minutes becomes 7.5), which is the format most payroll and timesheet systems require.
Frequently Asked Questions
How do I calculate a shift that spans midnight?
Use the "Overnight" option, which tells the calculator to treat the end time as occurring the following day rather than assuming both times fall on the same day.
Why do timesheets need decimal hours instead of hours and minutes?
Payroll systems calculate wages by multiplying hours worked by an hourly rate, which requires a decimal format (7.5 hours) rather than a time format (7 hours 30 minutes) for accurate arithmetic.
Can I use this for calculating total time across multiple shifts?
This calculator handles one time span at a time — for multiple shifts, you'd calculate each duration separately and add the decimal hour totals together.