How to set an alarm on your computer

The quickest way: an alarm in your browser

The alarm clock on this page works the same on Windows, macOS, ChromeOS and Linux. Choose the Alarm time, add a note such as Call with the team if you like, and press Set alarm. The list shows how long until it rings, and if the time has already passed today, the alarm is set for tomorrow.

Two conditions apply to every browser alarm: the tab must stay open and the computer must stay awake. The page asks your device to keep the screen on while an alarm is set, and the sound is scheduled in advance so it plays on time even if the tab is in the background. Press Test next to the sound once before you rely on it.

Windows 10 and Windows 11

Windows has a built in alarm app: Clock on Windows 11 and Alarms and Clock on Windows 10. Open the Start menu, type Clock or Alarms, open the Alarm tab and press the plus button to add an alarm. You can set the time, a name, repeat days, a sound and a snooze time, then save.

Windows itself warns that alarm notifications only show when the PC is awake. Most desktop PCs and many laptops go to sleep after a few minutes of inactivity, so check Settings > System > Power (named Power and battery or Power and sleep depending on the version) and set sleep to Never while plugged in, at least on the nights you rely on it. Do not disturb and Focus can also silence notifications; Windows 11 lets you add apps to priority notifications under Settings > System > Notifications.

Mac

Since macOS Ventura (version 13) the Mac has the same Clock app as the iPad. Open it from Launchpad or Spotlight (Command and Space, then type Clock), choose Alarms and add a new alarm with the plus button. On older macOS versions there is no alarm app; the usual workaround is an event in Calendar with an alert, or a reminder with a time in Reminders.

A Mac with its lid closed or in sleep will not ring. In System Settings, look at the display and sleep options under Lock Screen and, on laptops, Battery, and keep the Mac on power. If you are comfortable with Terminal, the built in caffeinate command keeps the Mac awake while it runs. Focus modes such as Do Not Disturb can hide alerts, so check the Focus status in Control Center before a nap.

Chromebook

Most Chromebooks do not come with a classic alarm clock app. The practical options are a browser alarm like the one on this page, or a Google Calendar event with a notification, which shows a pop up but usually only a short sound.

A Chromebook sleeps when you close the lid and dims and sleeps after a while on battery. Under Settings > Device > Power you can choose what happens when idle (for example keep the display on) and turn off sleep when the cover is closed. Plug in the charger so the battery does not run out overnight.

Make sure the alarm actually rings

Most failed computer alarms come down to one of a handful of causes. Go through this list once and the alarm will be reliable:

• Sleep: the computer must stay awake. Change the sleep setting, keep laptops plugged in and leave the lid open.
• Volume: system volume, the alarm's own volume slider and the speaker must all be up. Muted laptops are the most common cause of a silent alarm.
• Output device: if Bluetooth headphones are still connected, the alarm plays in the headphones on your desk.
• Muted tab: browsers can mute a site. Check that the tab does not show a crossed speaker icon.
• Sound after a reload: browsers only allow a page to play sound after you have clicked or pressed a key on it. If you reload the page, click anywhere on it once.
• Focus and Do Not Disturb: they can block notifications from apps; a browser alarm that plays its own sound is not affected, but the operating system alarm may be.
• Updates: Windows and macOS may restart overnight to install updates. Postpone them on nights you need the alarm.

Alarms for naps, reminders and work

A computer alarm is most useful during the day, when you are at your desk and your phone is on silent or in another room. Typical uses: a reminder five minutes before a call, the end of a parking ticket, taking something out of the oven, leaving for school pickup, or the end of a 20 minute power nap. Give each alarm a note so you know what it is for when it rings.

For naps, research on short daytime sleep commonly points to 10 to 20 minutes as the length that refreshes without grogginess; longer naps tend to reach deep sleep. Set the alarm before you lie down and add a few minutes for falling asleep. If you need a fixed duration instead of a clock time, a countdown timer is simpler; for work sessions with breaks, a Pomodoro timer repeats the cycle for you.

When the alarm rings, press Stop to end it or Snooze 5 min to hear it again five minutes later, as often as you like. You can keep several alarms in the list and switch each one on or off without deleting it.

When a computer alarm is the wrong tool

For waking up in the morning, a phone or a dedicated alarm clock is more dependable: a computer can restart for updates, lose power or fall asleep despite your settings, and a browser alarm stops working if the browser is closed. Use the computer alarm as a second alarm or for daytime reminders, and keep the critical one on a device designed for it.