.ICS File Extension

Calendar File

Developer Internet Engineering Task Force
3.5  |  598 Votes

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. For example, when users send a meeting request to others, they can share ICS files with them, who can import the meeting's details into their 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 events.

How to open an ICS file

You can open an ICS file with various applications. For example, 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 import the event details the file 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. While opening an ICS file with a text editor is not the best way to view an event's details, it does allow you to view the information without a calendar application.

How to convert an ICS file

You can convert an ICS file to a CSV file with a free online ICS to CSV converter, such as Indigoblue Free ICS to CSV Converter or ProjectWizards ICS to CSV Converter.

By converting an ICS file to a CSV file, you can import a calendar event into Microsoft Excel or another spreadsheet program.

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Programs that open ICS files

IronCAD 3D Scene

Developer IronCAD
3.5  |  53 Votes

An ICS file may also be a 3D scene created by IronCAD, a 3D and 2D CAD application. It contains one or more parts or assemblies that include colors, textures, lighting effects, and other properties. IronCAD users primarily save 3D scenes as ICS files and 2D drawings as .ICD files.

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Screenshot of a .ics file in IronCAD 2022
ICS file open in IronCAD 2022

IronCAD is a Windows CAD application that can create 2D and 3D models of real-life objects. Engineers primarily use IronCAD to design various objects for production, such as mechanical parts and furniture.

When you save a 3D scene with IronCAD, the software creates an ICS file to store its contents. To create an ICS file, select Menu → File → New Scene. After modifying the scene, select Menu → File → Save or Save As....

NOTE: IronCAD saves ICS files to the following directory by default:

Documents\​IRONCAD [version]

How to open an ICS file

You can open ICS files with IronCAD in Windows by:

  1. Selecting Menu → File → Open...
  2. Clicking the Open folder icon in the top toolbar Home tab

How to convert an ICS file

IronCAD can convert ICS files to many file types, including the following formats:

To export an ICS file with IronCAD, select Menu → File → Export.

Programs that open ICS files

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IC Recorder Sound File

Developer Sony
3.4  |  62 Votes

An ICS file may also be an audio file created by the Sony ICD-R100 voice recorder. It contains recorded audio, usually a personal memo or a conversation between two or more people. For example, an ICS file might contain an interview conducted by a reporter.

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The Sony IC-R100 is a voice recorder that Sony released in 1999. It allowed users to record and play back voice recordings saved as "messages." Each message was saved as an ICS file.

Users could transfer messages from their IC-R100 to a Windows PC using ICD-PCLINK software. This allowed users to store and play ICS files on their PC.

How to open an ICS file

You can open an ICS file in Sony Digital Voice Player, a free ICS audio player for Windows. You can also open an ICS file in Windows Media Player with the Sony Player plug-in installed.

Programs that open ICS files

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