If you're scheduling a meeting with other Outlook/Microsoft 365 users, the easiest method is to use Scheduling Assistant. It lets you see everyone's free/busy time and find a slot that works before sending the invite. Microsoft documents this as the recommended way to coordinate meetings and room resources. 

Outlook Desktop (Classic Outlook)

  1. Open Calendar.
  2. Click New Meeting.
  3. Add the attendees in the To field.
  4. Enter a meeting subject.
  5. Click Scheduling Assistant on the ribbon.
  6. You'll see:
    • Attendees listed on the left
    • A timeline showing each person's availability
    • Busy times blocked out
  7. Move the meeting time until you find an open slot for everyone.
  8. If your organization uses room mailboxes, click Room Finder and select an available conference room.
  9. Click Send.

New Outlook or Outlook on the Web

  1. Go to Calendar.
  2. Select New Event.
  3. Add attendees.
  4. Click Scheduling Assistant.
  5. Outlook will display:
    • Free/busy information
    • Suggested meeting times
    • Available rooms (if configured)
  6. Pick a suggested time or drag the meeting block to an available slot.
  7. Add Teams Meeting if desired.
  8. Click Send.

Useful Tips

  • Required attendees affect availability calculations.
  • Optional attendees are shown but won't prevent Outlook from suggesting a time.
  • Outlook only shows free/busy information, not details of others' meetings.
  • If someone appears blank, Outlook may not have access to their availability information