How do I calculate time differences across midnight?

Use the Time Difference mode and check the "End time is next day" checkbox. The calculator will correctly compute the duration across midnight.

What is decimal time?

Decimal time expresses time as a decimal number of hours. For example, 1 hour 30 minutes = 1.5 hours, and 2 hours 15 minutes = 2.25 hours. This format is commonly used for billing and timesheets.

Can I add days to a time?

Yes! In Add/Subtract mode, you can add or subtract days, hours, minutes, and seconds. The result shows the final time and indicates if it falls on a different day.

How do I calculate my work hours?

Use Time Difference mode. Enter your start time (e.g., 9:00 AM) and end time (e.g., 5:30 PM). The calculator shows total hours worked in both HH:MM:SS and decimal format.

Time Calculator — Add, Subtract & Find Time Difference Online

How to Use Time Calculator

1
Select a mode: Add/Subtract Time, Time Difference, or Time to Decimal.
2
Enter the time values in the input fields (hours, minutes, seconds).
3
For Add/Subtract, choose the operation and duration to add/subtract.
4
View the result instantly — formatted in multiple ways.
5
Use the copy button to copy results to clipboard.

About Time Calculator

"If I start at 9:45 and work for 6 hours and 20 minutes, what time do I finish?" If you've ever stared at a clock trying to do that math in your head, this time calculator is for you.

Three modes for different problems

Add/Subtract Time — Start with any time and add or subtract days, hours, minutes, and seconds. It handles midnight crossovers automatically, so "11:30 PM + 3 hours" correctly gives you "2:30 AM (+1 day)" instead of making you do the math. Quick-add buttons for common durations (+30 min, +1 hour, +8 hours) speed things up.

Time Difference — Enter a start and end time, get the exact duration. Shows the result in HH:MM:SS, decimal hours (for timesheets), total minutes, and total seconds. Check "end time is next day" for overnight shifts — because 10 PM to 6 AM isn't -16 hours.

Time to Decimal — Converts 1:45:00 to 1.75 hours. If you bill by the hour or fill in timesheets that want decimal hours, this saves you from doing "45 minutes ÷ 60" in your head every single time.

Who actually uses this

Freelancers tracking billable hours, nurses calculating shift lengths, project managers estimating timelines, students timing study sessions, and anyone who's ever Googled "what time is it 6 hours from now" at midnight.

Time Calculator