0000 vs 2400 Time
Updated June 15, 2026
0000 and 2400 both refer to midnight — the same exact moment. The difference is which day they belong to. 0000 is the start of a new day. 2400 is the end of the day that just finished.
Direct answer
0000 and 2400 are the same moment in time, but not the same date. 0000 Friday is the first minute of Friday. 2400 Friday is the last minute of Friday. Most organizations use 0000 as the standard and avoid 2400 entirely. Both equal 12:00 AM in 12-hour time.
Side-by-side comparison
| 0000 | 2400 | |
|---|---|---|
| Means | Zero hours, zero minutes | Twenty-four hours, zero minutes |
| Position in day | Start — first minute | End — last minute |
| 12-hour equivalent | 12:00 AM | 12:00 AM (same time) |
| Date association | New day | Day that just ended |
| Spoken as | "Zero hundred hours" | "Twenty-four hundred hours" |
| Common use | Military, aviation, logistics | Deadlines, event end times |
| Standard? | Yes — ISO 8601, NATO | No — non-standard, but used |
Who uses 0000?
The military, airlines, hospitals, railroads, and most computer systems all start the clock at 0000. It is the international standard. Military time runs from 0000 through 2359, one minute at a time.
In these systems, 2400 does not exist on the clock. After 2359 comes 0000 of the next day. This keeps things unambiguous: every timestamp has one correct value.
Who uses 2400?
2400 shows up in a few specific places:
- Business deadlines. "Submit by 2400 EST Friday" makes it clear the cutoff is before Saturday begins. If they wrote 0000 Saturday, people might think they have until the end of Saturday.
- Event schedules. A concert or festival that ends at midnight may list 2400 to avoid confusion about which day the event belongs to.
- Shift work. Some factories and warehouses use 2400 to mark shift change at midnight so the outgoing shift's paperwork stays on the correct date.
- Older railway timetables. Some European rail systems historically used 2400 for the last departure of the day, though most have switched to 0000.
Even in these cases, 2400 is more of a communication tool than a real clock value. The actual digital clock still reads 00:00.
Can a clock show 24:00?
Most digital clocks cannot show 24:00. They run from 00:00 to 23:59 and then roll over. But some specialized equipment — particularly in Japan, where 24:00 is sometimes used in TV schedules and late-night venue listings — can display it.
In Japan, you might see a bar or club listed as open "18:00 – 24:00" or a TV show airing at "24:30" (which is actually 00:30 the next day). This convention is unique to Japanese scheduling and is not part of the international 24-hour standard.
Japanese "30-hour clock" convention
Some Japanese TV schedules and late-night venues extend past 24:00 — you may see times like 25:00 (1:00 AM) or 27:30 (3:30 AM). This is not 24-hour time. It is a scheduling trick to keep all listings for a single programming day on the same date. A show airing at 25:00 Monday technically airs at 1:00 AM Tuesday, but the schedule keeps it under Monday.
Which one should you use?
If you are writing a schedule, log, or timestamp that will be read by other people or systems, use 0000. It is the standard. It works everywhere.
If you are setting a deadline and there is any risk of date confusion, writing "by 2400 Friday" or simply "by midnight Friday" may be clearer to a non-technical audience. But on forms, databases, and digital systems, stick to 0000.