Applies to: SharePoint 2010, SharePoint 2013, Office 365​

You can add many events in your SharePoint calendar. You can use one or more categories in your SharePoint calendar.
How about if you want to filter your SharePoint calendar based on your category.
You can filter other list on the fly by adding FilterField and FilterValue but you cannot do the same in SharePoint Calendar. Unless you create separate views in calendar you cannot filter it.
Following Service allows you to Filter calendar on the fly without creating different views.

​Click on the following link to see how Filter Calendar works. Look at the result below after you click the link:

https://aasoftech.sharepoint.com/Demo/SitePages/FilteredCalendar.aspx?FilterField1=room&FilterValue1=Room%20A1&FilterField2=Category&FilterValue2=Meeting

https://aasoftech.sharepoint.com/Demo/SitePages/FilteredCalendar.aspx?FilterField1=room&FilterValue1=Room%20A4&FilterField2=Category&FilterValue2=Birthday
https://aasoftech.sharepoint.com/Demo/SitePages/FilteredCalendar.aspx?FilterField1=room&FilterValue1=Room%20A3&FilterField2=Category&FilterValue2=Business​​​​​​​​​​​​​​​​

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Do it in 20 minutes:
No installation! Simple instruction:
1- Use SPFilterCalendar template and create calendar using the template.
2- Make sure you don’t delete the following Fields from the calendar.
Title
Category
Meeting Room
AllFields
3- Add data to your calendar
4- You can change Choices in Lookup Fields for Category and Meeting Room but don’t change Field names.
5- Provide the following links at the bottom of your calendar page in your Content Editor Web Part.