Convert an Outlook .ost file to a .pst file in a single step, producing a ready‑to‑open Outlook data file. The conversion preserves the entire mailbox structure—including every folder, sub‑folder, email, contact, appointment, and attachment—exactly as it appears in the original .ost. — Only Unicode .ost files are supported; ANSI .ost files are outside the tool’s scope —

Full folder hierarchy retained

The converter reproduces the exact folder tree from the source .ost inside the resulting .pst. Every default folder (Inbox, Sent Items, Drafts, Deleted Items, Outbox, Junk Email) and every custom folder or sub‑folder appears with the same name and nesting level, allowing the mailbox to be opened in Outlook with its original structure intact.

All Outlook item types transferred

Emails, contacts, calendar appointments, tasks, notes, and journal entries are carried over to the .pst. Per‑message properties such as read/unread state, importance, follow‑up flag, and categories are also preserved, so the converted file contains a complete, searchable mailbox rather than just the mail folders.

Message content and attachments stay intact

Message bodies in HTML, plain‑text, or RTF are stored verbatim. Attachments and inline images remain embedded in the same messages, and all standard headers (From, To, Cc, Subject, Date) are kept exactly as they were in the original .ost. No re‑encoding, rendering, or external processing occurs during conversion.

Efficient conversion with fallback for complex files

Most Unicode .ost files are converted via a fast in‑place header change, which avoids copying each item and finishes quickly even for large mailboxes. When the fast path isn’t possible, the tool creates a new .pst and copies all folders and items; the resulting file is identical, only the process takes longer.

Limits and scope

Upload size per tier: The maximum file size depends on the user’s account tier; anonymous users have a lower cap, free Aspose accounts a higher cap, and premium tiers allow larger uploads.
Batch submission: A single submission can include multiple .ost files, which are processed sequentially and returned as a .zip archive containing one .pst per input file.
Download link retention: The generated download link is valid for 24 hours after the conversion completes.

How to convert OST to PST

STEP 1

Upload your file

Click inside the file drop area to upload your files or drag & drop them.

STEP 2

Convert

Click on the "Convert" button. Your files will be uploaded and converted immediately.

STEP 3

Download

Download link of converted PST files will be available instantly after conversion.

STEP 4

Feedback

Check conversion results and send us your feedback.

FAQ

Will the folder hierarchy be preserved in the converted PST?

Yes, the converter reproduces the exact folder tree from the source .ost inside the resulting .pst, including all default folders and every custom folder or sub‑folder with the same names and nesting level.

Are email attachments and inline images kept in the PST?

Attachments and inline images embedded in messages are stored inside the PST unchanged, with no external links or separate extraction step required.

Do per‑message properties such as read/unread status and categories survive the conversion?

Per‑message properties—including read/unread state, importance flag, follow‑up flag, and categories—are preserved in the PST.

What is the maximum file size or number of files I can upload for conversion?

The allowed upload size varies by account tier: anonymous visitors have the smallest limit, a free Aspose account raises the cap, and premium tiers permit larger files; the exact limits are listed on the pricing page.

How long is the converted file available for download?

The download link remains active for 24 hours after the conversion finishes, after which it expires.

OST to PST

Produces a Unicode .pst that retains the full folder hierarchy and all Outlook items, ready to open directly in Outlook.