Outlook Calendar Reminder Settings, Explained

What is the Outlook default reminder time?

The Outlook default reminder time is 15 minutes before an appointment or meeting starts. Reminders alert you to upcoming calendar items such as appointments and meetings, and by default, reminders occur 15 minutes before the start of these calendar items.

That 15-minute default applies to new items you create yourself, not to meetings someone invites you to. The default reminder setting in Outlook is mainly used to set your own reminders on the meeting or calendar, not to set reminders for attendees — when you accept a meeting request, the reminder time is set according to the meeting organizer's default reminder setting, which is often 15 minutes. That's why two people can look at the same invite and see different lead times. It also explains a common complaint we see in threads about Outlook reminders not showing up or firing too late — it's covered in more depth in our Outlook reminders don't ring on iPhone guide, and the behavior is the same root cause whether the symptom is "no alert" or "wrong alert time."

All-day events get a different default entirely. This default reminder time does not work for all-day events — regularly, the default reminder time for all-day events is 18 hours in Outlook 2010, and 0.5 day in Outlook 2013. If you juggle both timed meetings and all-day blocks, expect to set those reminders manually each time.

How to change the Outlook reminder time (default and per-event)

To change the default reminder time in classic Outlook for Windows or Mac, go to File, then Options, then Calendar, and pick a new value under Default reminders. Click the File tab, click Options, click Calendar, then under Calendar options, next to Default reminders, click a new time, and click OK. This only sets what new items start with — you still have the choice to specify a custom reminder time for each calendar item that you create.

New Outlook and Outlook on the web use a different path. To change the default reminder time there, click the gear icon, then View all Outlook settings, then Calendar, then Events and invitations, then Default reminder. Note that this setting doesn't carry across accounts: in new Outlook, the default reminder time is per-account, not per-device, so if you switch between work and personal accounts, each has its own default and you need to set it for each account separately.

On desktop, you aren't limited to the dropdown's preset options. If you're using the Outlook desktop app, you can still set any reminder time you want by typing it manually in the Reminder box when you create or edit a calendar item — for example, you can type 4 hours or 18 hours and it will be converted to the equivalent time. That workaround does not appear to be an option for macOS desktop users, so Mac users are stuck with the preset list unless they adjust the account-level default.

One limitation worth planning around: you must use the Outlook desktop application for Windows or Mac to change this setting — it is not available in Outlook on the web or the mobile apps. If you mostly work from a phone, this is one of several reasons Outlook's own reminder system behaves inconsistently across platforms — something we break down further in Google Calendar vs Outlook reminders compared.

Why does my Outlook reminder keep resetting to 15 minutes?

It resets because the reminder time on an accepted meeting comes from the organizer's settings, not yours. If you want to ensure you always get a reminder a specific amount of time before a meeting, you might need to manually change the reminder time for each meeting you accept — there isn't a way to automatically override the organizer's default reminder setting when you accept a meeting request.

This is a structural limitation, not a bug you can patch with a setting. Some users have reported that even the account-level fix stops working in certain builds: in at least one version of new Outlook there doesn't appear to be a way to change the default reminder time at all, according to one forum answer marked helpful by another user. If your job depends on a reliable lead time — not whatever an organizer picked — a calendar alarm app that reads the event time directly and lets you set your own lead time per calendar, like Pealo, sidesteps the organizer-default problem entirely. Our guide on setting different alert lead times per calendar covers how that works alongside Outlook, Google, and iCloud calendars at once.

How do I change the Outlook reminder sound?

Go to File, then Options, then Advanced, and find the Reminders section — that's where both the sound toggle and the sound file picker live. Select the File tab, select Options, select Advanced, and under Reminders, select or clear the Play reminders sound check box; if you choose to play a reminder sound, you can either use the default sound file or select Browse to select a sound file that you want to play.

To turn reminder sound off entirely rather than change it, the same checkbox does the job. If you don't want an auditory alert every time a reminder pops up, you can tell Outlook not to play a noise at all by going to File, Options, Advanced, scrolling to the Reminders section, and switching off Play Reminder Sound, then clicking OK.

Custom sounds are limited to one file format. The reminder can only recognize .wav files, so you have to select a .wav sound file in the Reminder Sound File dialog box. If you have an MP3 or other format you want to use, you'll have to convert it first before Outlook will accept it as a reminder sound. You can also set a sound per individual appointment rather than globally — open the appointment, click the Reminder dropdown, then Sound, and browse to a file, the same way you'd set a one-off reminder time.

Worth knowing: this setting only affects Outlook's own pop-up reminder, which fires while the desktop app is open and your Mac or PC isn't silenced. It has no effect on reminders delivered to your iPhone — those depend on iOS notification settings and whether Focus or Silent mode is active, which is a separate system covered in our Outlook calendar alarms that actually ring page.

Desktop Outlook vs new Outlook vs mobile: what can you actually control?

Not every reminder setting exists in every version of Outlook — the desktop app has the most control, the web and new Outlook have less, and mobile has the least. The table below summarizes where each setting lives.

This setting is account-specific: if you have multiple email accounts added to Outlook, the default reminder time applies to the calendar for your primary mailbox, and changing it does not affect other users' calendars or shared calendars — you need appropriate permissions to change settings on a delegated calendar. If you're trying to standardize reminder behavior across a work calendar and a personal one, it's worth reading our comparison of work and personal calendars on one alarm list, since Outlook's per-account defaults mean you're configuring this twice, not once.