01:00 in 12-Hour Time
01:00 is 1:00 AM.
Written 0100 in military time and said “zero one hundred hours”. Going the other way, 1:00 AM is 01:00.
The 01:00 hour is the small hours, where the 24-hour clock earns its keep — 01:00 and 13:00 can never be confused on a night-shift handover.
24-hour clock
01:00
12-hour clock
1:00 AM
Said aloud: “zero one hundred hours” on the 24-hour clock, “one o'clock at night” on the 12-hour one.
Why 01:00 converts the way it does
Every hour from 1 to 11 in the morning reads the SAME on both clocks — only the leading zero and the AM label differ. That is why converting a morning time feels like it did nothing: 01:xx and 1:xx AM are the same digits. The 24-hour form still pays for itself, because it cannot be mistaken for the afternoon.
The minutes are the same on both clocks — a whole hour stays a whole hour — and 01:00 is at night, which is the information the AM/PM label is carrying.
Need this time to actually do something? Set an alarm for 1:00 AM, or use the timer to count a length of time instead of waiting for a clock time.
Common questions
What is 01:00 in 12-hour time?
01:00 is 1:00 AM. The minutes are unchanged; the hour keeps its number and takes AM.
What is 1:00 AM in 24-hour time?
1:00 AM is 01:00, written 0100 in military time.
How do you say 0100 out loud?
In military time it is said "zero one hundred hours". On a 12-hour clock the same moment is "one o'clock at night".