This tutorial shows how the Outlook Web App (OWA) can be used to publish your calendar with people outside your organization by either sending an email invitation, or creating a shareable URL.
Open the App Launcher in the upper left hand corner of the window and select Calendar.
Right click the calendar you want to publish. Or, if you are using a touchscreen device, touch and hold the calendar name. Select Sharing permissions from the sub-menu.
To share your calendar with someone outside your organization, type in the person's email address in the Send a sharing invitation in email field. Click the use this address: pop up that appears.
Select the level of access from the drop down menu, and click share.
An email will be sent to the address you typed in. Depending on the client that the receiver is using, if you send them the Subscribe to calendar URL, they may need to use the specific subscribe feature within their client to view your calendar data.
*Note: Subscribing to a calendar in this method does not allow for any modifications to be made as it only provides 'read' access to the calendar items.
Click the gear icon and under Your App Settings select Calendar.
*Note: This will show a version of the calendar in a browser, and is ideal for sharing with people who do not have microsoft accounts.
In the left hand menu, select Calendar publishing. Choose the Calendar you'd like to share and adjust the right level of access from the Select Permissions drop down.
Select Save then right click the html link to copy it, then share with those you want to see your calendar.