21:57 is 9:57 PM on a 12-hour clock and "21:57 Hours" in Military Time. We use this system throughout the world (not just the military) and leverages a 24-hour time clock rather than the 12-hour AM/PM system known to most English-speaking countries. Below are ways to convert 21:57 through a time chart, automated calculator, and ways to convert by hand.
| 24-hour format | 12-hour format |
|---|---|
| 21:57 | 9:57 PM |
A quick cheatsheet for all time conversions like 9:57 PM. Click the clock. Select your time. We'll highlight the row for the time you choose.
It is easy to convert from 24-hour time to 12-hour time once you know a few tricks. The primary difference between the two is that the hours in a 24-hour clock go all the way up to 23 (from 0 to 23). In a 12-hour clock, the hour resets to 1 after noon (midday). Follow the steps below to convert 21:57 to 12-hour time.
24-hour time is used in aviation, military, meteorology, logistics, and other fields. The 12-hour clock is only used in 18 countries globally, including the United States and Canada. 24-hour time and military time are very similar! See our military time converter for more information.
| 24 Hour Clock | 12 Hour Clock (AM/PM) | Military Time |
|---|---|---|
| 21:57 | 21:57 | 2157 |
| 22:02 | 22:02 | 2202 |
| 22:07 | 22:07 | 2207 |
| 22:12 | 22:12 | 2212 |
| 22:17 | 22:17 | 2217 |
| 22:22 | 22:22 | 2222 |
| 22:27 | 22:27 | 2227 |
| 22:32 | 22:32 | 2232 |
| 22:37 | 22:37 | 2237 |
| 22:42 | 22:42 | 2242 |
| 22:47 | 22:47 | 2247 |
| 22:52 | 22:52 | 2252 |
| 22:57 | 22:57 | 2257 |
| 23:02 | 23:02 | 2302 |
| 23:07 | 23:07 | 2307 |
| 23:12 | 23:12 | 2312 |