.ICS File Extension

.ICS File Extension

File Type 1

Calendar File

Developer Internet Engineering Task Force
3.5  |  354 Votes
Category Misc Files
Format Text

What is an ICS file?

An ICS file is a calendar file saved in a universal calendar format used by several email and calendar programs, including Microsoft Outlook, Google Calendar, and Apple Calendar. It allows users to share calendar information on the web and over email. ICS files are most often used to send meeting requests to other users, who can import the meeting's details into their own calendars.

More Information
Screenshot of a .ics file in Apple Calendar
ICS file open in Apple Calendar

In 1998, the Internet Engineering Task Force created the iCalendar, or ICS, file format. ICS files are plain text files that contain information about a calendar event, including the event's:

  • Title
  • Summary and description
  • Start and end times
  • Location
  • Alert trigger

The ICS format is a universal calendar file format that all popular calendar applications, including Microsoft Outlook, Apple Calendar, Google Calendar, and Mozilla Thunderbird Lightning Calendar, create and recognize. Because all popular calendar applications can use ICS files to add event details to a calendar, ICS files are the most common type of files used to exchange calendar information. Most commonly, office workers and other professionals use ICS files to send each other meeting requests. You may also receive ICS reminders for an upcoming birthday, holiday, trip, party, or other event.

How to open an ICS file

If you have a calendar application, such as Microsoft Outlook, Google Calendar, or Apple Calendar, installed on your device, you can double-click an ICS file to automatically import the event details it contains into your calendar.

If necessary, you can also manually import an ICS file into your calendar app. For example, to import an event into the web version of Google Calendar:

  1. Click the Gear icon that appears in the program's upper right-hand side.
  2. Select Settings → Import & export.
  3. Select Import and import your ICS file. The event(s) it contains will be added to your calendar.

If you are having trouble importing your ICS file into a calendar application, you can open the file in any text editor, such as Microsoft Notepad (Windows) or Apple TextEdit (Mac), to view the event information it contains. For example, you can see the event's start and end times (including time zone) listed in the file's DTSTART and DTEND lines. Opening an ICS file in a text editor is not the best way to view an event's details, but it does allow you to view the information without a calendar application.

How do I convert an ICS file to a CSV file?

If you need to import a calendar event into Microsoft Excel or another spreadsheet program, you can convert your ICS file to a CSV file. To do so, use a free online ICS to CSV converter, such as IndigoBlue or Project Wizards' free ICS to CSV converters.

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Programs that open ICS files

Updated March 2, 2021
File Type 2

IronCAD 3D Drawing File

Developer IronCAD
3.6  |  40 Votes
Category CAD Files
Format N/A

What is an ICS file?

Three-dimensional model or scene created with IronCAD, a 3D CAD program; may contain one or more 3D objects with colors, textures, lighting effects, and animation data.

More Information

NOTE: ICS files may automatically open in a calendar program such as MS Outlook due to the iCalendar file association. To open ICS files in IronCAD, you may need to right-click the file, select "Open With..." and choose IronCAD as the program.

Programs that open ICS files

Free Trial
Updated June 23, 2008
File Type 3

IC Recorder Sound File

Developer Sony
3.5  |  43 Votes
Category Audio Files
Format Binary

What is an ICS file?

Audio file created by a Sony IC recorder (e.g., the Sony ICD-R100), a handheld device used for recording personal messages; commonly used for storing voice audio, which is useful for forensics and legal environments, as well as for general personal memos.

Programs that open or reference ICS files

Updated July 7, 2017

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