What Is 0000 in Military Time? Midnight, Explained

A shift schedule says the night crew clocks out at 0000. Does that mean they finish tonight, or does their shift technically end tomorrow? It's a strange question to have to ask about a number that looks like it should just mean "nothing" — four zeros — but 0000 is doing real work: it's the label for the exact instant one calendar day ends and the next one begins.

This page is about that one specific number: what it means, why it isn't written as the hour that would logically follow 2359, the narrow case where you'll see 2400 used instead, and the real situations where the distinction has actual consequences. For the broader rules of reading and converting military time, see what military time is and the full military time chart.

0000 is midnight. It is the first instant of a day, not the last — the moment the clock resets after 2359 and a new date begins. In 12-hour time, that same instant is written 12:00 AM. There is no separate "0000 versus midnight" question; they're the same thing, just written in two different notations.

Said out loud, 0000 is "zero hundred," or more formally "zero hundred hours" — most people in casual speech just say "midnight" instead. The full rules for pronouncing military time, including this case, are covered in how to say military time out loud.

The 24-hour clock counts continuously from 00 to 23 and then resets. There is no 24 hour in normal use, the same way a car's trip odometer resets to zero rather than continuing past 999 — the day doesn't get a 25th hour, it starts over. That reset is 0000: the clock's way of saying "a new day has begun," not "the old one has ended."

This is a deliberate design choice, not an accident. Numbering the start of the day as 00 means every hour of every day is labeled exactly once, with no duplicate numbers and no ambiguity about which half of the day you're in — the same property that makes the rest of the 24-hour clock unambiguous. Treating midnight as the start keeps that property intact; treating it as the end of the previous day would break it, because then the last moment of one day and the first moment of the next would look identical.

0000 and 2400 point to the exact same instant. The difference is which day each one is considered to belong to, and it only comes up in specific technical writing — you will rarely see 2400 in day-to-day military or civilian use.

The one place 2400 shows up with any regularity is describing when something closes: a venue listed as open "2000–2400" is communicating that it closes at the boundary of the current day, rather than implying it reopens the moment the next day starts. Outside that narrow framing, 0000 is the correct and expected form, and it's what every timestamp, log, and schedule on this site — and almost everywhere else — uses by default.

This is the part that actually trips people up, and it has nothing to do with the notation itself — it's a language problem. Saying "midnight on Tuesday" is genuinely ambiguous in everyday English: does it mean the midnight that opens Tuesday, or the one that closes it (which is the same instant as the midnight opening Wednesday)? People use it both ways depending on context, and that's exactly the kind of gap that 0000 paired with an explicit date is meant to close.

Written as a full timestamp — 0000 on a specific date — there's no room left for interpretation: it is unambiguously the first instant of that date, the moment right after the previous date's 2359. That's the whole value of the notation. The confusion only creeps back in when someone writes just "midnight" in prose without pinning it to one date or the other.

This isn't an abstract technicality. A handful of everyday situations hinge on exactly which day 0000 counts as:

• Hotel and travel bookings. A reservation or flight departure listed for "midnight on the 10th" needs to specify whether that's the start of the 10th or the start of the 11th — the two are 24 hours apart.
• Contracts and legal deadlines. A deadline that expires "at midnight" on a given date is far safer written as 0000 on the following calendar date, removing any argument about which side of the boundary applies. For the general rule, note that legal and contractual time conventions can vary by jurisdiction — confirm the specific wording locally rather than assuming a universal standard.
• Shift handoffs. A night shift ending "at midnight" and a day shift starting "at midnight" need to agree on the exact same instant, or there's either a gap with nobody covering it or an overlap where two people think they're responsible.
• Billing and subscription cycles. A charge or cutoff set for midnight on a renewal date determines whether that date's activity counts toward the old cycle or the new one.
• Medication and hospital charting. Doses logged around the midnight boundary need the exact date attached, since "just before midnight" and "just after midnight" can be only seconds apart in real time but a full day apart on the chart.

When the exact boundary matters, three habits remove almost all the ambiguity:

• Pair 0000 with the explicit date it belongs to, rather than writing "midnight" alone in a sentence.
• Default to 0000, not 2400, unless you're specifically describing a closing boundary in a context where that convention is already established (like posted business hours).
• In 12-hour writing, spell out "12:00 midnight" instead of "12:00 AM" when the stakes are high — 12:00 AM is technically correct but is misread often enough that the words remove all doubt. For the general 12-hour-clock version of this rule, see what AM and PM actually mean.