Lesson 18 — Activity 2: From 24-Hour to Standard Time

Getting Ready

Now that you have had some practise in converting from standard time to 24-hour time, you will learn to convert from 24-hour time back to standard time.


Courtesy of Pixabay

From 24-Hour to Standard Time

While there are a number of advantages to using the 24-hour clock, there are also some disadvantages. Look at the picture of the 24-hour clock above.

    Most analog clocks and watches have dials of 12 hours; this makes it necessary for the user to associate two numbers for each hour. For example, 1 is also 1300.

    Some clocks, like the one above, have two sets of 12 hours displayed on the same dial, which can be hard to read or cause trouble because you are not sure which number to look at.
    Some people find the idea of 0 or 00 hours unnatural.

    In written English, there isn't any notation for indicating that a time uses the 24-hour clock, unlike a.m. and p.m. on the standard clock. A 24-hour time between 1:00 and 12:59 might not be recognized as a time by some readers.

Because of these reasons and also because some people just prefer to use the standard clock, it is important to know how to convert from the 24-hour clock to the standard clock.

Here's how to convert.

  •  If the time is below 1200 hours, eliminate any unnecessary zeros, add a colon, and write in a.m.

For example, if you are asked to convert 0924 hours to standard time, eliminate the zero in front, put a colon between the 9 and the 2, and add a.m. after. This will give you 9:24 a.m.

Courtesy of Public Domain

  • If the time is more than 1200 hours, you need to add another step. The first thing to do is subtract 1200 from the time. Then follow the steps above, EXCEPT that you will now write p.m. after the time instead of a.m.

For example, let's say that you are asked to convert 2025 hours to standard time.

 First, because it is higher than 1200 hours, you need to subtract 1200 from it.

2025 – 1200 = 0825

Next, eliminate the zero in front because you don't need it, then put a colon between the 8 and the 2, and write p.m. after it to give you 8:25 p.m.

Courtesy of Pixabay

Try This:

Convert the following 24-hour times to standard times:

0810 hours

1845 hours

0810 hours becomes 8:10 a.m.

1845 hours becomes

1845 – 1200 = 0645

6:45 p.m.


Try This!

Click here to try a Self-check Activity to practise converting from the 24-hour clock to the standard clock.

Images courtesy of www.imagesgoogle.com

Digging Deeper

Click here to try a game to match standard and 24-hour times.