Time Duration Calculator
Add or subtract hours and minutes without clock arithmetic. Your work stays on this device whenever possible.
How to use Time Duration Calculator
- Choose Calculator Mode: "Work Shifts & Payroll (Multi-Interval / Overnight)" or "Time Adder / Subtracter (H:M:S)".
- For shifts, type one line each in the pattern Start Time, End Time, Break Mins, Description, using 24-hour clock times such as 22:00, 06:30, 45, Tuesday Night Shift.
- Enter your Hourly Billable Wage ($) to turn the total time into gross earnings.
- For arithmetic instead, fill Duration 1 and Duration 2 in hours, minutes and seconds and pick + Add or - Subtract in Operation.
- Press "Calculate Duration" and read the totals and the time-card table.
Worked example
In shift mode with wage 25.00, enter "22:00, 06:30, 45, Tuesday Night Shift". The window runs 22:00 to 06:30 the next day, which is 510 minutes. Subtract the 45-minute break to get 465 minutes, or 7 hours 45 minutes, 7.75 decimal hours, and gross pay of 7.75 × 25 = 193.75.
When to use this tool
- Totaling a week of shifts, including a night shift, for a freelance invoice.
- Adding two clip lengths given as hours, minutes and seconds to plan an edit.
- Converting a duration into decimal hours for a billing system that does not accept minutes.
Important limitations
Shifts spanning multiple calendar days beyond a 24-hour single rollover period should be split into individual daily shift entries to ensure accurate payroll overtime categorization.
Frequently asked questions
How does the tool detect an overnight shift?
If the end time is earlier than or equal to the start time, it adds 24 hours to the end. That handles 22:00 to 06:30 automatically. A shift with identical times is therefore counted as 24 hours.
How is break time applied?
The minutes in the third column are subtracted from the shift's gross length, and the net length never drops below zero. The table lists the break beside each row so you can audit it.
Which time format is expected?
Use hours and minutes separated by a colon on the 24-hour clock. Rows without a readable start and end are skipped without warning, so a missing row in the table usually means a typo.
Does the adder allow negative results?
Yes. If Duration 2 is larger than Duration 1 in subtract mode, the answer carries a minus sign, and the result shows total seconds and decimal hours as well as hours, minutes and seconds.
Does it calculate overtime or taxes?
The main calculator still multiplies decimal hours by the single wage with no overtime or rounding. The Payroll rounding, weekly overtime & CSV panel below it adds optional nearest 5/6/15-minute or 7-minute-rule rounding and daily/weekly overtime thresholds, with pay and a downloadable CSV -- turn it on if you need those numbers.