Time Calculator

About the Time Calculator

The time calculator adds and subtracts time values written in hours, minutes and seconds. It handles the base 60 carrying for you, so 40 minutes plus 35 minutes correctly becomes 1 hour 15 minutes.

It has two modes. Add or subtract times totals a list of durations. Each row holds one time value, and the sign next to it decides whether that row is added or taken away. Press “Add another time” for more rows, and use the × button on any extra row to remove it. Add time to a clock time starts from a set time of day, such as 9:00 AM, and shows the clock time you reach after adding or subtracting a duration.

The result updates as you type. You get the answer in four formats: hours and minutes, clock format (h:mm:ss), decimal hours and total minutes or seconds. The Clear button empties every box but keeps your rows in place.

The clock time mode works from any start time you choose, such as a shift that starts at 7:30 AM or a flight that leaves at 11:15 PM. To count forward or back from the current moment instead, use the time from now calculator, which runs on your live clock.

How to Use the Time Calculator

1. Choose a mode at the top of the calculator.
2. Type the hours, minutes and seconds for each time value. Empty boxes count as 0.
3. Set the sign on each row to plus to add it or minus to subtract it.
4. Press “Add another time” if you have more values to combine.
5. Read the total in the result panel. It updates with every change.

Values above 59 are allowed. Typing 90 in the minutes box is read as 1 hour 30 minutes. Decimals work too, so 1.5 hours means one and a half hours.

How to Add Time Manually

Adding time by hand follows one rule: carry at 60, not at 100. Seconds roll into minutes at 60, and minutes roll into hours at 60.

1. Add the seconds. If the total is 60 or more, subtract 60 and carry 1 minute.
2. Add the minutes, including any carried minute. If the total is 60 or more, subtract 60 and carry 1 hour.
3. Add the hours, including any carried hour.

A second method converts everything to seconds first. Multiply hours by 3,600 and minutes by 60, add the totals, then convert back by dividing by 3,600 for hours and by 60 for minutes. This method never misses a carry, which is why the calculator uses it internally.

How to Subtract Time

Subtract seconds first, then minutes, then hours. When the top number is smaller, borrow 1 from the next column and add 60, not 10.

If the second time is larger than the first, the result is negative. The time calculator shows this with a minus sign, such as −1 h 20 min.

Time Addition and Subtraction Examples

The table shows common sums worked out with the same method the calculator uses. The last column gives each result in decimal hours, the format used by payroll and billing software.

Result Formats Explained

• Hours and minutes, such as 4 h 15 min, is the easiest format to read.
• Clock format, such as 4:15:00, is used in logs, spreadsheets and video timelines. Hours keep counting past 24, so 27:20:05 means 27 hours, not a time of day.
• Decimal hours, such as 4.25, is the format payroll and invoices need. The time to decimal calculator has a full conversion chart.
• Total minutes and total seconds help when a form or a program asks for a single unit.

Common Uses of a Time Calculator

People use a time adder to total work hours from several shifts, add the length of video or audio clips, combine running splits and add flight legs into one travel time. Freelancers use it to total time spent on a client before invoicing.

For a single work shift with a break, the hours calculator is faster. For a full week of punches with overtime, use the time card calculator. To measure the time between two clock times, use the time duration calculator.

Frequently Asked Questions