If you aren’t in the armed forces, you probably don’t encounter the use of the 24-hour clock very often. Though it is a more adept way of telling time and has more precision than the standard time system, it requires math and is therefore inferior in every possible way. No matter how cerebral you are, when you live with time that goes from 1 to 12 it’s like having your food bowl moved whenever anyone suddenly whips out “eighteen hundred hours” and suddenly you are transported back to desperately trying to figure out an algebra problem on the blackboard while the class snickers.

## Why Is Military Time Difficult?

All you’re really doing in military time is subtracting 12 from any number thrown at you that is above 12. That should be easy, but for some reason it’s not. Point of fact, it’s not intellect that does this to us, it’s actually a matter of pattern and routine. Our brains are designed to try to simplify things for us by creating pockets of information that we can can grab easily, particularly for tasks we use on a consistent, daily basis, such as telling time, walking, talking, or writing. When we acclimate to doing these things in a particular way – think of the route you drive to work or the store – we stop really thinking about them, because they’re programmed into our gray matter. Then someone throws a detour into the works and now we’re stuck because we not only have to work out a new system, but we actually have to convince our brain to temporarily un-learn the old system. Hence the trouble.

## How To Re-Wire Your Brain

What we need to do in order to prevent the stumbling block is to create two separate pockets for time. One for plain-Jane 12-hour clocks, and one for military time. The beginning of this process is comprehending the two systems to create a mental line of separation between civilian hours and those that do their push-ups.

## Understanding Civilian Time

North Americans use a 12-hour clock that covers each half of the 24-hour day. They are split into ante meridiem (a.m.), loosely translated into “before the middle”, and post meridiem (p.m.), “after the middle.” The middle here refers to noon, largely thought to be the middle of the day as it’s 12 hours exactly from midnight, bisecting the 24-hour period.

Generally this system is fine so long as you explain which half of the split day you’re talking about, but it does become more complex when you end up with time periods that pass over the noon marker. Somehow having an event go from 10 o’clock to 1 o’clock is three hours; counter-intuitive and mathematically irresponsible, really.

## Understanding 24-hour Time

Different countries have different ways of dealing with time, but like the metric system the 24-hour clock has been adopted internationally because there’s less ambiguity. Instead of chopping the day into two halves, necessitating the explanation of every hour into a.m. or p.m., the 24-hour clock counts every hour separately. It begins at midnight, when a new day officially begins. Instead of midnight being “12:00,” in 24-hour time, midnight is written as 00:00. 1 o’clock is 01:00 with 2 o’clock being 02:00 and so on.

When the clock reaches what is colloquially 1 pm, instead of starting the count over, it becomes 13:00 hours. The last minute of each day is 23:59, after which it goes back to the quad-zero midnight look to mark a new day (0000).

This method of timekeeping is actually far more prolific outside of North America, again mirroring the metric system. It’s actually older than the customary system Americans use, though wasn’t adopted in the U.S. until 1920, when the navy recognized they needed to orchestrate with other forces using a universal time system. WWII saw it move into the Army and then into common usage in the early 1940’s. Since North Americans were introduced to it via the fine people in uniform, it became known as “military-time” and the name stuck.

## Turning Civilian Into Military

The way to turn civilian time into a military format is to subtract 12 from the hours of any number larger than 12. Thus, 13:00, which is 1 pm is the result of 13:00-12:00 = 1 (pm).

Even simpler is to use place values. Often you don’t need to subtract 12, but merely subtract 2 from the military time numbers, then remove the first number. Here’s how this is accomplished.

If the first number in the time is a “1” and the number is higher than 12:00 (i.e. 13:00-24:00) you can discard it. So, hours 13:00-19:00 become 3:00 to 9:00. That isn’t the right time, but it’s closer. Now you subtract 2 from each number off to get the proper times. Like this:

13:00 is the time. Since it is larger than 12 and begins with the numeral “1” you can discard the “1”.

Now you have 3:00

Subtract 2:00 and you have 3:00 – 2:00 = 1. Add your pm, and 1 pm is the time.

That’s a spunky little trick for 1 pm (13:00) to 7 pm (19:00) but after that there’s a 2 at the beginning of each hour (8 pm = 20:00) and if we just drop that, we get a mess.

The reason you dropped the “1” previously is because the 1’s in the tens column of both the number “12” and the hours (13:00) cancel each other out during subtraction. When you have a “2” in the tens column as you would with 20:00, it doesn’t cancel out the 2, it just turns it into a 1. Therefore the rule is:

If the time is larger than 12:00 and starts with a 1, drop the 1. If it starts with a 2, that becomes 1. Then you’re just dealing with subtracting the remaining 2 to get your real time.

### Example:

22:00.

The first number is a 2 which turns into a 1 when converting to standard time. Now it’s 12:00.

All that is required is to subtract “2” creating the equation 12:00 – 2:00 = 10

10:00

22:00 = 10 pm.

## Using Military Time

The math trick is helpful, but it’s also good to practice so that you can create that 24-hour knowledge we discussed early on. You can do this any way you like, but often it’s helpful to change a single clock in your house to military time. Often the computer is best since most people are looking at their monitor through much of the day. Then, whenever you look at that clock, you’ll be forced to practice changing the time in your mind. After a few weeks (or maybe months) it will become second nature to be able to tell military time like a jarhead. Or, at least do less math when you see it.

When writing out military time, do not use colons. They were used above to aid in the examples, but traditionally you would write the time as 0000 for midnight, 0001 for 12:01, 0002 for 12:02 am, and so on up to the last minute of the day which is 2359 – 11:59 pm.

As if it wasn’t bad enough that the clocks are completely different, the verbiage you spit out when you read military time is also different. “Hundred hours” is used in place of “o’clock” so instead of saying “It’s 5 o’clock” you would say “It’s zero-five-hundred hours.” The reason for the zero is all military time units have four places. So 5 is 0500, thus zero-five-hundred hours. You can say “oh” in place of “zero” but actual military personnel use the zero so there’s absolutely no risk of mistakes.

Also, hundred is the standard measurment. Don’t ever say thousand, always hundred. Thus, 2000 – which is 10 o’clock pm – is read as “Twenty-hundred hours” not “Two-thousand hours.” 1717 would be read as “Seventeen seventeen hundred hours” and 1942 would be read “Nineteen forty-two hundred hours.” or, if you’re sure of yourself, you can drop the “hundred hours” so long as you’re sure everyone will get your meaning.

## A Note On “Zulu”

Here’s the thing about an international time system, there’s more than one time zone in the world. When you have troops trying to organize, each of which is in a different time, you need to have a set standard time. When someone adds “Zulu” onto a time, as in “Ninteen twenty-six hundred hours Zulu” they are saying “7:26 pm in Greenwhich, England. The reason being, that’s where the Coordinated Universal Time aka Greenwich Mean Time is. In fact, each time zone has a letter replacement assignment with names like “X-Ray, Tango, Whiskey” and even some that have their own half hour time zones, such as Echo Star Time Zone.

If any letters accompany a time, it means they’re talking about that time in that time zone, not the time where they currently are, unless they are in that time zone, though that’s unusual since they know what time it is where they are.