Free OLM Converter
Convert to Any Format

OLM is the archive and export format used by Microsoft Outlook for Mac. When you export your mail, calendar, or contacts from Outlook on a Mac, the result is typically an .olm file. Unlike PST (Personal Storage Table), which is used by Outlook on Windows, OLM is specific to the Mac version of Outlook. The file is not a single binary database like PST; it is a ZIP archive. If you open an OLM file with a ZIP tool, you will see a collection of files and folders, including XML files that store email metadata and content. Converting OLM means reading that ZIP structure, locating the XML (or other) data that represents each email, and turning it into formats you can use elsewhere — such as EML (one file per message), MBOX (single mailbox file), CSV (for spreadsheets), or HTML, TXT, and JSON for backup and analysis.

Our free OLM Converter processes everything on your device. You drop a .olm file, and the tool checks for the ZIP signature (first two bytes 0x50 0x4B, i.e. "PK"). It then uses a ZIP library to open the archive and iterate over the entries. For each entry that looks like XML or text, the tool reads the content and searches for known Outlook for Mac XML tags, such as OPFMessageCopySubject, OPFMessageCopySenderAddress, OPFMessageCopyToAddresses, OPFMessageCopyContent, and OPFMessageCopyTimeSent. From these tags it builds a list of extracted emails with subject, from, to, date, and body. If ZIP parsing fails or no XML is found, the tool falls back to scanning the raw file for readable text blocks (e.g. lines containing "From:", "Subject:"), similar to a PST fallback. Once emails are extracted, you can export them as EML (one file per message), a ZIP of EML files (PST-limited option), MBOX, CSV, HTML, TXT, or JSON. All processing happens on your device; nothing is uploaded. OLM conversion is especially useful for Mac-to-Windows migration: moving from Outlook for Mac to Outlook on Windows, or to Thunderbird, Gmail, or Office 365.

Common conversion scenarios include migrating from a Mac to a Windows PC (OLM to EML or MBOX, then import into Windows Outlook or another client), backing up Outlook for Mac mail in a universal format like EML, importing into Gmail or Office 365 by first exporting to EML/MBOX, and analyzing mail metadata in a spreadsheet via CSV. Because the converter works online, you can use it on any operating system — you do not need Outlook for Mac to convert an OLM file. Just open the tool, drop your .olm file, choose an output format, and download. For full native PST creation (a single .pst file that Outlook for Windows can open directly), desktop tools or Outlook itself are often used; this tool provides a PST-limited option (ZIP of EML files) and full EML/MBOX/CSV/HTML/TXT/JSON export so your data is never stuck in the OLM format.