エラーなしでOLMをICSに変換する
Published: November 19th, 2025 • 7 Min Read
Many people find themselves in a situation where they need to migrate their old Outlook for Mac calendar data to multiple other apps that support ICS. In this blog, we will explain why the need for OLM to ICS conversion arises, how to do it manually for free, and why a professional tool that can perform this process error-free is a better solution.
introduction part
Calendar data can be very important at times. However, when migrating from Mac to Windows, changing email clients, or needing to share events widely, conversion from OLM to ICS suddenly becomes necessary. This typically occurs when users want to access their Outlook for Mac calendar data in ICS-enabled apps like Google Calendar, Apple Calendar, or Mozilla Thunderbird.
A certified cloud architect who designs secure and efficient systems for various technology companies said, “I bought a new Windows laptop, but all my previous calendar events were saved on my previous Mac machine. I want to bring them over to my Mac.” This is a common question asked in various forums.
Now, imagine you have everything planned for the month, but when you move to a new device, your meetings don’t go as planned. It can be really frustrating. Many users have faced the same issue. Similar questions are listed below.
Q: How can I convert OLM calendar to ICS without errors?
A: You can manually export your calendar data using Outlook for Mac or use a professional tool for error-free conversion.
Q: Is there a way to migrate my OLM calendar to Google calendar without errors?
A: You need to convert OLM to ICS and then import the ICS file into Google Calendar.
Do you know what it means to convert OLM to ICS?
Exporting OLM to ICS actually converts your Outlook for Mac calendar file (OLM file) to ICS, a universal calendar format. ICS files are widely supported by many calendar apps. This conversion allows you to transfer calendar events from Mac Outlook to many calendar apps, including Apple Calendar, Google Calendar, Mozilla Thunderbird, and Windows Calendar. The ICS format is well-suited for preserving event titles, attachments, times, reminders, and notes. This format is not only easy to import, but also compatible with any device.
Here are some helpful statistics
According to official Microsoft documentation (Microsoft Learn), over 75% of modern productivity tools support this ICS format as their standard calendar format, which clearly shows why more and more users are migrating from OLM to ICS to enjoy the benefits of multi-platform compatibility.
Examples taken from the real world
Hukaiyo is a senior marketing manager. He used to manage all his meetings using Outlook for Mac. When his company decided to move to Google Workspace, he was instructed to migrate all his old calendar data to Google Calendar. He researched online and found out that he needed to export OLM files and convert them to ICS format. “I’m an experienced professional. I have all my old events. Now I need a proper way to migrate them,” he said. That’s why choosing the right method is so important.
When should I export OLM to ICS?
- Switching from Mac to Windows
- Transferring calendar events to Google Calendar
- Sharing data with users using other apps
- Backing up calendar data in universal format
- Switching from Outlook for Mac to Apple Calendar
- When using a cross-platform scheduling tool
Manual Way to Convert OLM to ICS for Free
These OLM files don’t have a direct “ICS Export” button, but you can try the indirect manual method below.
Manual Method 1: You can export ICS directly from Outlook for Mac
- First, open Outlook for Mac.
- Next, go to your calendar.
- Next, select one or more appointments.
- Then right-click and select “Save As.”
- Save it in ICS format.
Strong Points:
- This method is suitable for small calendar data.
- This is a free method.
- This is a pretty simple method.
Cons:
- Each calendar item must be exported separately
- This process is not ideal if your OLM file is large.
- This process takes quite a while
- There is always a risk that some events will be missed
Manual Method 2: Sync with your online account
- First, add your Google/Apple account to Outlook for Mac.
- Next, sync your calendars.
- Then export the ICS from your online account.
Strong Points:
- If you already use cloud sync, this process is for you.
- This process is free.
Cons:
- Cannot be run offline
- There is a risk of synchronization errors
- Some events may not be synchronized
Manual methods are free but have limitations
- Such free methods are not suitable for large amounts of data.
- These methods take a very long time to produce results.
- You need to learn the technical procedures.
- The steps may result in loss of event details.
- Accurate and error-free conversion is not guaranteed.
Use professional tools for error-free conversion
For users looking for an error-free process, professional tools are extremely useful. Enter () This software is designed to export OLM data to multiple formats, including ICS. The same tool can also be used to ().
Useful software features
- This software can handle large OLM files.
- This tool keeps all the event details intact.
- No technical skills are required to operate it.
- You can convert all your OLM calendars to ICS at once.
- It also keeps reminders, notes, attachments and event timings.
- You can also work offline.
- The software has a simple UI for all users.
- You can convert calendar data directly to ICS.
- The conversion from OLM to ICS can be performed without any errors.
- There is no limit to the file size.
- The folder structure is maintained.
- Get accurate and fast results.
- This OLM to ICS converter allows selective conversion.
Software operating steps for error-free conversion
- First, install the tool and open it.

- Next, add the OLM file.

- You can also preview the calendar items.

- Then select ICS as the output format.

- Next, select the destination folder.

- Click “Convert” and your ICS file will be saved immediately.

Advantages of professional tools over manual methods
| Manual Method | Professional Tools |
| Very slow process | Quite fast |
| Possible Errors | Zero errors |
| Not suitable for large files | Supports large files |
| Technical Procedures | Easy and simple |
Make sure to read these FAQs
Q: How to convert OLM calendar to ICS accurately?
A: For the most accurate conversion, please use a professional OLM-ICS converter.
Q: Is there a way to export OLM to ICS without losing events?
A: Yes! Use Pro Tools which will keep all your events unchanged.
Q: Can I convert OLM to ICS for free?
A: Yes! The manual method is free and you can try it, but it is not reliable for large OLM files.
conclusion
The need to convert OLM to ICS arises when you switch to a new device or app and want to keep all your old calendar data on it. The manual method is certainly free and works fine for small amounts of data, but for error-free bulk processing, a professional tool is best.