Time Duration Calculator

The Time Duration Calculator is a tool you can use to compute the total time passed since a start time up to an end time. This calculator uses a 12-hour format so you just have to enter exactly the start and end times on their respective fields.

🕐 Time Duration Calculator

⚙️ Display Settings

Start Time


End Time


✍ Result

-- : --

To put it into words, the time duration between the start time of to the end time of is -- : --.

Total Time in Value
Decimal Hours

How to Use the Time Duration Calculator?

At first glance, I know you'll figure it out right away how to use the Time Duration Calculator. You can just see the input fields with labels and a calculate button so all pieces comes together, you could get your results quickly.

On the other side of the coin, I just want to elaborate more on the usage of the calculator and the detailed results it offers not just the exact time duration as you would expect, but also relevant results you could potentially use.

  1. Step 1

    First, check on the ⚙️ Display Settings to know the available time options. You'll have the choice to include or exclude hours, minutes, seconds and/or milliseconds in your calculation. Take your time checking this feature.

  2. Step 2

    Next, let's go to the Start Time, by default it has Hours, Minutes and Meridiem. If you have Seconds and Milliseconds enabled, then you'll see them as well. Now enter the start time, say you want to use , enter 7 on hours field, 45 on minutes. AM is the default of Meridiem so that's good for this example.

  3. Step 3

    Then, let's do the same thing on End Time. For example, let's try . Enter 5 on Hours field, 30 on Minutes field. The default of end time meridiem is PM so that's good to go.

  4. Step 4

    Finally, since our inputs are done, just click on the Calculate button and results will be displayed just below the "✍ Result" part.

On the calculator inputs, you can only enter the maximum value with respect to the time unit. For hours, since we are doing a 12-hour time format, the maximum hour you can input is 12. Otherwise, it will automatically proceed to the next field (minutes input).

If you try to force input a value that is beyond the maximum, it won't let you do that. What you always get is the maximum value. If you add 99 on minutes input, it will revert to 59 not 60 because if it's 60, that only means 1 hour, just add it to hours.

What are the Results of the Calculation?

The most important result of the calculation why this calculator is created for you is found just below the "✍ Result" part of the form. Following our example on the usage steps, the output should be: "9 hours and 45 minutes". The results will be on this format.

Furthermore, a written form of the inputs and the output will be summarized just below the main result.

To give you more detailed results, there's a result table on the output part where you'll get the total time in Decimal Hours, Minutes, Seconds and even Milliseconds!

How to Manually Calculate the Time Duration?

There's two mostly used ways in other to come up with a proper solution regarding the time duration calculation. The first one is by utilizing the 24-hour time format and the second one is using decimal time format.

1. Time Duration Calculation Using 24-Hour Format

To get the time duration, what we can do is that we can just subtract the end time from the start time. This way, we can get the time passed between these two times.

For this example, let's get the time duration where our start time is 8:30 AM and end time is 5:45 PM.

This will be our formula:

    Time Duration = End Time - Start Time

Following our formula, we can do our computation into this format:

    Time Duration = 5:45 PM - 8:30 AM

The first thing we need to do is to convert the time into 24-hour format. You can also check out 24-Hour Format Converter for your reference.

To convert our start time from 8:30 AM to a 24-hour format, we can just write it as 08:30. However, on end time of 5:45 PM, we need to add 12 on the PM or afternoon. So that would be 17:45.


First, let's start with the minutes just like usual way of doing mathematics. Let's subtract 5 with 0, the answer would be 5.


Then, the next number from the last is 4 and 3, let's subtract them and the answer would be 1.

107 17:45

Finally, on the hours part, since 7 minus 8 would return negative value, let's borrow 1 from the next number and add 10 the borrower (10 + 7), now we have 17. So, 17 minus 8 is equal to 9. For the last part 0 - 0 = 0 so let's bring down 0.

So, the answer would be 9 hours and 15 minutes. You can confirm this on the calculator above and you'll confirm that the answer coincides with our manual computation.

2. Time Duration Calculation Using Decimal Time Format

This second way of manually calculating time duration is a bit lengthy but it does solve the same problem.

So, following our example on the first solution, these will be our given times:

    Time Duration = 5:45 PM - 8:30 AM

The calculation using decimal time involves these steps:

  1. Convert the times (start time and end time) into 24-hour time format.
  2. Convert the time units into the smallest unit. For example, 08:30, convert the 08 hours into minutes since the minutes is the smallest unit. Then, add the result to the existing minutes with is 30.
  3. Subtract the start time from the end time following the time duration formula.
  4. Convert the decimal time to standard time format.

Now that we have the steps needed, let's proceed with our manual computation using the decimal time format.

Step 1: Let's convert the given times into a 24-hour format.

    Start Time = 08:30
    End Time = 17:45

Step 2: Now we can convert these times into minutes.

    Start Time Hours to Minutes Conversion
    = 08 * 60
    = 480 minutes

    Start Time Total Minutes
    = 30 + 480
    = 510 minutes

    End Time Hours to Minutes Conversion
    = 17 * 60
    = 1020 minutes

    End Time Total Minutes
    = 45 + 1020
    = 1065 minutes

Step 3: Based on our computation we now have 510 minutes as start time and 1065 minutes as end time. Since they both have minutes unit, we can subtract them directly.

    Time Duration
    = 1065 minutes - 510 minutes
    = 555 minutes

Step 4: After the subtraction, we now have the initial result of 555 minutes. Let's convert that into a decimal time format, then into a standard time format.

    Minutes to Time Format
    = 555 minutes / 60
    = 9.25 hours

    Decimal Minutes to Minutes
    = 0.25 * 60
    = 15 minutes

Finally, we have a different solution to our problem but strikes the same result. Although it's a little bit tedious process, we can't deny the fact that this too is another way of getting our exact time duration.

    Final Answer
    = 9 hours and 15 Minutes