Date & time
Time Converter & Sum
Convert hours, minutes and seconds, or add a list of durations.
Runs in your browser · No file or text uploads
Preparing your tool…
What Time Converter & Sum helps you do
Add work sessions or video lengths without mixing in dates or time zones. Each line is converted to seconds before the total is calculated.
How to use it
- Select the input unit.
- Enter one duration per line.
- Calculate the total in hours, minutes, seconds and HH:MM:SS.
Input and output example
INPUT
01:30:00 00:45:30OUTPUT
02:15:30.000 · 8,130 seconds
Supported formats and limits
- Up to 1,000 lines. Each value and the total must have an absolute value of at most 1 trillion seconds.
- In this tool, 01:30 means 1 hour 30 minutes. Use decimal units when needed.
- This is duration arithmetic; dates, leap seconds and daylight-saving changes are not applied.
How the result is calculated
1 hour = 60 minutes = 3,600 seconds. Add all values in seconds. Numeric results use up to 6 decimal places; HH:MM:SS is rounded to milliseconds.
Frequently asked questions
Can I subtract a duration?
Yes. Use a leading minus, such as -00:15:00, or enter a negative number in the decimal input modes.