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Time Calculator

Add or subtract multiple time values in hours, minutes, and seconds to get a total time.

Enter time values in HH:MM:SS format. Use the + / − selector to add or subtract each entry.

Total Time

About the Time Calculator

The Oneyfy Time Calculator lets you add or subtract multiple time values to find a total duration. This is useful for summing up task durations, calculating project time, or working out elapsed time across multiple segments.

How to Use

  1. Each row has an operation selector (+ or −), and fields for hours, minutes, and seconds.
  2. Enter your time values. Hours can exceed 23 (e.g., 36 hours is valid).
  3. Click + Add Row to add more time entries.
  4. Click Calculate Total to see the result.

How It Works

All time entries are converted to total seconds. Add-rows contribute positively and subtract-rows contribute negatively. The result is converted back to hours, minutes, and seconds. If the result is negative, it is displayed with a minus sign.

Example

Add 2:30:00 + 1:45:30 − 0:15:00 = 4:00:30 (4 hours, 0 minutes, 30 seconds).

Frequently Asked Questions

Yes. This is a duration calculator, not a clock. Hours can be any positive number, making it ideal for tracking project hours over multiple days.
A negative total is displayed with a minus sign, indicating more time was subtracted than added.
You can add as many rows as you need. There is no built-in limit.