Set an alarm for 20:21

⏰ The alarm will ring at 8:21 PM — in 18 h 18 min
Alarm at 8:21 PM
⏰ 8:21 PM
18Hours
:
18Minutes
:
5Seconds
Saturday, October 24, 2026

Set an alarm for another time

Best bedtimes to wake up at 8:21 PM

Go to bed atSleep cyclesSleep
11:06 AM69 h
12:36 PM57 h 30 min
2:06 PM46 h
3:36 PM34 h 30 min

Assumes about 15 minutes to fall asleep and sleep cycles of roughly 90 minutes. Cycle length varies from person to person, so treat these as estimates.

Snooze times after a 8:21 PM alarm

Snooze length1st2nd3rd
5 minutes8:26 PM8:31 PM8:36 PM
9 minutes8:30 PM8:39 PM8:48 PM
10 minutes8:31 PM8:41 PM8:51 PM

Nine minutes is the traditional snooze length on many alarm clocks.

About 8:21 PM

The 8 PM hour begins prime time on U.S. television (8–11 PM Eastern), when the most people watch TV.

Press “Start Alarm” and keep this tab open; press “Test Alarm” first to check the volume.

About 8:21 PM

12-hour clock8:21 PM
24-hour clock20:21
Military time2021
In wordsTwenty-one minutes past eight
Part of the dayEvening

Questions about a 20:21 alarm

How do I set an alarm for 20:21?

Open this page, press “Start Alarm” and leave the tab open. The alarm rings at 8:21 PM, which is 18 hours, 18 minutes from now.

What time should I go to bed to wake up at 8:21 PM?

For five full sleep cycles, go to bed around 12:36 PM; for six cycles, around 11:06 AM.