How to Convert OST to OLM for Outlook on Mac – Simple Guide
Jackson Strong | August 21st, 2025 | Email Migration
Summary: If you are moving from Windows to Mac and need to access your Outlook emails, you may find OST files that don’t open in Outlook for Mac. This is because Windows Outlook uses OST files, while Mac Outlook uses OLM files. To make them compatible, you need to convert OST to OLM format. In this guide, we will explain both manual and automated methods.
What are OST and OLM Files?
OST File: A local copy of your mailbox created by Outlook on Windows when you use Exchange or IMAP. It lets you work offline and syncs when you reconnect. OST files, however, work only with Windows Outlook.
OLM File: A data file used by Outlook for Mac. It stores emails, contacts, calendars, and tasks.
Since both formats belong to Outlook but for different platforms, you cannot directly import OST into Mac Outlook.
Is Manual OST to OLM Conversion Possible?
Direct manual conversion from OST to OLM is not supported. But here are workarounds:
1. Set up the same email account in Outlook for Mac.
If your OST is connected to Exchange/IMAP, just configure the account in Mac Outlook. Your emails will sync automatically.
Limitation: Works only if the OST file is still linked to the server.
2. Export OST data to PST in Windows, then import to Mac.
Outlook on Windows allows export to PST. Later, you can use import features in Mac Outlook.
Limitation: Needs Outlook installed on Windows and does not work with orphaned/corrupted OST files.
If OST is orphaned, corrupted, or too large, manual tricks may fail. In such cases, you need a converter tool.
How to Convert OST to OLM Directly? (When Manual Fails)
If you cannot access your OST file in Outlook, an OST to OLM converter helps. It converts OST emails with attachments, contacts, and calendar events into OLM format safely. Advik OST Converter is one such tool that helps you export OST files to OLM format with all attachments intact.
Also, you don’t need any technical skills to use this tool. Just add your OST file, choose the OLM format, and the software will do the rest. It ensures that all email attachments and formatting remain unchanged during the conversion process. Plus, it supports batch conversion that allows you to export multiple OST files to OLM at once.
Download the free version of the tool to understand the complete workings of this tool.
Steps to Export OST to OLM File
Step 1. Download and install the software on your Windows PC.
Step 2. Load OST files and folders into the panel by clicking on the Select File option.
Step 3. Here, you will get a preview of folders and you can select the folder according to your need.
Step 4. From Multiple saving options, select “Outlook for Mac (OLM)”
Step 5. Finally, hit the Convert button to import OST data to Mac OLM format.
Done! Now, wait for a few moments, and you will get all your OST files converted into OLM file format with all the attachments.
Now, check out the video tutorial to understand in a better way.
Watch How to Convert OST File to OLM
Key Features of the Best OST to OLM Converter Tool
- No Outlook Installation required: It is a standalone utility that does not require Outlook installation to provide you with the desired results. The tool does not depend on any email application and can work independently without any issues.
- Convert Multiple OST files at once: If you have a large number of files and you want to convert all of them then the Batch Conversion feature is an ideal way to do it quickly. Users can easily convert OST to OLM within a few couple of moments. Users can select multiple files or folders at the same time.
- Export OST to OLM with Attachments: The best tool to import OST to OLM format can successfully preserve and transfer all your attachments with exact structure. That means it can easily migrate all your emails with attachments without any data damage.
- Support Different File formats: This is one of the most flexible tools that help users convert OST files to 30+ file formats directly and securely. All you have to do is download the tool, run it on the PC, and select the desired file format. This tool converts OST to PST, MSG, HTML, EMLX, vCard, ICS, and more.
- Easy-to-use Tool: There is no need to be a professional expert and it does not need any technical configuration to set up the tool. You can convert OST files to OLM format via this utility in an effortless manner, even if you are a first-time user. It has a simple user-friendly panel.
- Free Demo available: You can analyze the software by downloading the program’s free version to export OST emails to OLM format. It allows users to save only 25 emails from OST to OLM for testing purposes. For unlimited migrations, you can purchase the full version of the tool.
Conclusion
OST and OLM are Outlook file formats for different systems. If your OST file is still connected to the server, you can sync your emails directly in Mac Outlook. But if it is orphaned or inaccessible, manual tricks won’t work. In that case, using a professional OST to OLM converter is the safest way to migrate your emails, contacts, and calendars without data loss.
