Converting to 24 hour time

This is something everybody in America should do.

I'll explain first how to convert from 12-hour to 24-hour time a.k.a. "military time". This is very easy.

Convert from 12-hour to 24-hour:

For any afternoon hour, meaning 1pm to 11pm, add 10 then add 2 and you have the correct hour for 24-hour time.

Example using 2pm: 2+10=12. 12+2=14. The correct hour for 2pm is 14.

Example using 9pm: 9+10=19. 19+2=21. The correct hour for 9pm is 21.

Example using 11pm: 11+10=21. 21+2=23. The correct hour for 11pm is 23.

Convert from 24-hour back to 12-hour:

For any afternoon hour (13 to 23), subtract 10 then subtract 2 and you have the correct hour for 12-hour time.

Example using 13: 13-10=3. 3-2=1. 1pm is the correct hour.

Example using 17: 17-10=7. 7-2=5. 5pm is the correct hour.

Example using 20: 20-10=10. 10-2=8. 8pm is the correct hour.

Why is there no conversion of morning hours?

Morning hours from 12-hour to 24-hour are identical except for midnight, which in 24-hour time is 0. Every other hour is the same. 4am is 4, 5am is 5, 8am is 8, and so on.

Why I switched to 24-hour time on my watch

I did this to solve two problems that kept happening enough to bother me.

Problem #1: Waking up after a nap at dusk and not knowing if it's morning or evening.

Day is day, night is night and a quick glance out a window tells you that instantly. If dark, night. If bright, day. Easy.

However, dawn and dusk, as in sunset and sunrise, appear nearly the same when looking out a window.

Sometimes I will take a quick nap. If I fall asleep at 7pm and wake at 7:30pm, the light in the sky when looking out a window basically looks the same as it would at 7:30am. Yes, I know nightstand 12-hour clocks show a little dot indicating PM. I don't see that when just waking up. All I see are the bigger numbers.

Now I just look at my watch in 24-hour time. Instead of 7:30pm, I see 19:30 and I know for a fact it's evening hours because the 19 is so different from 7pm.

Problem #2: Incorrectly setting the watch alarm

The display on my digital watch, while plenty legible, only shows a small indicator for AM or PM (usually just PM). And that's the way it is on all digital watches.

For example, if I set an alarm for what I thought was 2pm, I would mistakenly set it for 2am because I wasn't paying attention to the PM indicator.

With the watch in 24-hour time, I never get the hour wrong anymore. Instead of 2pm, now it's 14:00.

Weird at first, but I'm getting used to it

The only two clocks I switched over to 24-hour time are my watch and phone since those are the only two I use to set alarms with.

And as far as other things I use that tell time, there are certain ones where I can't set the clock to 24-hour even if I wanted to. An example of this is my car. 12-hour clock only. That's not really a big deal, but still, it's annoying I can't switch it to 24-hour.

What I look at to tell the time when I wake (my watch) and where I set alarms (watch and sometimes phone) are the most important.

I'm already at the point where I've memorized what "weird" hour numbers mean in 12-hour time. 19 is 7pm, 21 is 9pm, and so on. Again, weird at first, but it makes a lot of sense when used regularly.

People read time digitally anyway, so...

Most use the phone when they want to know what time it is. And kids these days aren't being taught how to read analog clocks anymore...

...so I'm mystified as to why we still even bother using 12-hour time in the first place.

The only place 12-hour time actually makes sense is on an analog clock since there are 12 hour markers on the dial. Yes, there are 24-hour analog dial watches like this and this (where the traditional 6 o'clock position is actually 0:00) but I've never seen anybody wearing one.

The more I use 24-hour time, the more I'm coming to appreciate it just for the fact it's much faster and easier to tell the difference between morning and afternoon hours.

I'm not saying to throw away all the analog watches and clocks. But I am saying that in the electronic digital environments, which quartz digital watches and phones are, we should all be using 24-hour time.

Published 2021 Mar 23