How is 00:23 in 24-hour format pronounced? “Zero twenty-three” or “oh twenty three”?

Honestly I’ve never heard an English speaker give the time out load in 24 hour format outside of the military. Even if someone used the 24 hour format on their phone, they probably wouldn’t say it out loud. Most people would say “Twenty-three past midnight” or “twelve twenty-three”.

Never really heard it in 24 hr time, people here just say "Twenty-three past midnight."

I’d say 23 past midnight as a civilian, as its the only way to be truly clear. I’d say it like that regardless of whether I was using 12 or 24 hour time as it is clear and systematically neutral. “Zero Twenty Three” is also correct but it feels like I’m in a military helicopter if I say that lol.

The 24-hour format is generally not used verbally. Only in writing.

At the fire department we usually say it as “23 minutes” While communicating on the radio. For example you might hear , dispatcher: “engine 3 respond to Martin Luther king drive” engine 3: “engine 3s responding” dispatcher: “engine 3 I have you responding at 23 minutes”

In an aviation context (pilots, air traffic controllers, etc.) we would say “zero zero two three”

I would say 12:23 AM.

In the states we don’t use 24-hour time and so this would be 12:23 AM. We’d say it that way

As an American using 24-hour time for my own convenience separate from any group that follows particular conventions, I'd want to read it as "oh twenty-three" (side note, numbers like twenty-three or eighty-one have hyphens when written out, and something like 56,617 would be "fifty-six thousand six hundred seventeen") but I'd actually say it as "twelve twenty-three AM" because I expect anyone I'm speaking to to prefer 12-hour time.

If I had to say it as the numbers I'd go for "oh", default is just past midnight. At least outside the US military lol

When i was in the army they call this “zero zero two three”

(I'm from the Netherlands where we use 24-hour format) I think it's a common misconception that people in countries that use the 24-hour time format pronounce it as in the military. There's a big difference between military time and 24 hour clock format. I would read out loud a time like 16:20 as "twenty past four" and for your example "Twenty-three past midnight." Whether it's PM and AM is usually clear by the context and if we want to be specific we just say "in the morning/afternoon/evening" after the time

Fairly unusual to hear in American context. "Twelve twenty-three AM" for common civilian context.

In British English, while 24 hour clocks are commonplace, we would not read it out litterally. "23 minutes past midnight" or "23 past" if the hour was evident by context.

In the UK we will usually just read the time on a 24 hour clock and then convert it to the twelve hour clock when reading the time aloud. It’s a bit of a linguistic quirk.

Assuming the time is “00:23”, 99% of people would simply say “12:23”. The only deviance would be military context or perhaps strange mannerisms in specific locations that say it military style. That would be “Oh twenty three”

Going to deviate from most of the answers. I speak British English and would say “double o twenty three”

Obviously it is "7 minutes till oh-dark-thirty" edit: /s in case it's needed

Zero zero twentythree. But really really depends on context.

Minuit vingt-trois

I would say "twelve twenty three AM". Similarly, if the time is 13:23 I would say "one twenty three PM". In other words, you just say the 12 hour time.

Might well depend on where you are, but I’ve heard train tannoy announcements that would say “midnight twenty-three”.

If I literally read it out, "Zero Twenty-Three". But if I saw it on a clock and was describing the time to someone else, I'd just say '23 past midnight'.

Zero 23 hours

I say Zero Zero twenty theee

If you're being exact, 23 minutes past 12. In general, most people would round up and say 25 past 12.

Twelve twenty three.

I say "midnight twenty-three"