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Date & time

Add Time Calculator

Add a list of hour-minute-second durations and convert the total to decimal hours.

Date conventions explained belowClear start and end values
Date workspace
Date workspace

Check which endpoints and calendar conventions are included.

See the method

Choose your dates and times

Runs on your device

Your time calculation

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter durations — hh:mm or hh:mm:ss, one per line.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

Parse each duration into seconds, sum them, then divide into total hours, remaining minutes and seconds. Hours may exceed 24 because these are durations, not clock times.

A WORKED EXAMPLE

Using durations — hh:mm or hh:mm:ss, one per line = 1:30 2:45 0:20:30, the result is 4:35:30. Change these example inputs to match your task; use the method above to check each step.

Understanding your result

No. 1:30 means one hour and thirty minutes, which is 1.5 decimal hours. The output reports both formats.

What to keep in mind

Durations must be nonnegative. This does not interpret clock-time intervals or daylight-saving transitions.

Common questions

Is 1:30 equal to 1.30 hours?

No. 1:30 means one hour and thirty minutes, which is 1.5 decimal hours. The output reports both formats.

Can a duration exceed 24 hours?

Yes. Enter 30:00 for thirty hours. The total is not wrapped around a clock.

Methodology maintained by ClarityKit. How these tools are built and checked.