Best OST to PST Converter Software in 2026: Four Tools Compared

An OST file is basically a local copy of a mailbox. Outlook creates it when you add an Exchange, Microsoft 365 or IMAP account, and it stays tied to that account and that profile. That’s why you can’t double-click it, or drop it into somebody else’s Outlook and expect it to open. Most days nobody cares. Then a mailbox gets deleted, a server dies, or Outlook throws an error and won’t touch the file, and suddenly that OST is the only place your emails still exist. An OST to PST converter opens the file on its own and saves the contents as a PST, which any Outlook profile can read.

We compared four of them: EdbMails, Stellar Converter for OST, Kernel OST to PST Converter and Shoviv OST to PST Converter. Everything below comes from each vendor’s own product page, plus a few public software listings, checked in September 2026. When a page didn’t say something, we wrote “not stated” instead of filling the gap with a guess.

Worth knowing up front: this site belongs to the company behind EdbMails, so EdbMails is listed first. We tried to treat the other three the same way, limits and prices included. Even so, test whatever you pick on a copy of your own file before you pay for it.

Do You Actually Need an OST to PST Converter?

Maybe not. Figure out which of these three situations you’re in first, because the cheapest fix is often already inside Outlook.

• The mailbox is still on the server and Outlook opens fine. Just export from Outlook. In classic Outlook that’s File, Open & Export, Import/Export, then Export to a file and pick Outlook Data File (.pst). Nothing to buy.
• The OST is out of sync or full of errors, but the mailbox is healthy on the server. Close Outlook, move the OST to another folder and let Outlook rebuild it. Hold on to the old file for a while, in case something was only ever stored locally.
• The mailbox or account is gone, the profile is gone, or Outlook simply won’t open the file. This is what converters are for. Outlook can’t reattach an orphaned OST, so you need something that reads the file directly.

Whichever one you’re in, copy the OST first and work on the copy. On most Windows machines the file sits in C:\Users\YourName\AppData\Local\Microsoft\Outlook.

How to Choose an OST to PST Converter: Quick Checklist

These are the questions we’d ask about any tool, including ones that aren’t on this page:

• What state is the file in? Healthy, corrupt, orphaned, encrypted? Make sure the product page names your case and doesn’t just say “OST files”.
• What do you need out of it? PST only, or also EML, MSG, HTML or PDF for single messages?
• Where is the data going? Into a PST file, or straight into a Microsoft 365 or Exchange mailbox with no PST in between?
• How many files? One OST is easy. Fifty is a different job, and some editions only handle one at a time.
• Does it need Outlook? Some tools need Outlook installed for part of the work. Find out which part before you start.
• What does the free trial let you do? Some let you save a few items per folder. Others only let you look. You want one that lets you test a real export.
• How much control do you get over the PST? Splitting, date and sender filters, picking individual folders.
• What are the licence terms? One year or lifetime, how many machines, and whether batch conversion or direct export sits behind a pricier edition.
• What happens when it fails? Check for real support and a refund policy.
• Does it leave your original alone? It should only read the OST. You should still work on a copy.

What an OST File Can (and Can’t) Give Back

No converter can recover what was never in the file. In cached mode Outlook keeps a local copy of the mailbox, but not always the whole mailbox. Anything that never synced down won’t be there. The same goes for server-side settings, permissions, mailbox rules, and Online Archive content that wasn’t cached. Heavy corruption takes a bite out of what’s readable too. So be a little suspicious of any tool that promises everything, and compare item counts after a test export.

OST to PST Converter Comparison at a Glance

Here’s the quick overview. The details and sources come after the table.

Reviews of Four OST to PST Converter Tools

1) EdbMails OST to PST Converter

EdbMails scans healthy, offline, orphaned, corrupt or otherwise inaccessible OST files and pulls out whatever is still present and readable. It works on the file itself, so you don’t need the original Exchange server, the Windows domain or the Outlook profile. You can preview emails, attachments, contacts, calendars and tasks before exporting anything, and pick single folders or items instead of converting the whole file.

For output you get PST, EML, HTML and MHT. It copes with both ANSI and Unicode OST files, splits the PST by size, brings back deleted items where they’re still recoverable, and gives you a report with item counts at the end. It can also push recovered data straight into Microsoft 365 or Exchange Server, and the vendor says the application puts no limit on the size of the source OST. Pricing starts at $45 according to the vendor’s page, and the free trial exports up to 30 items per folder.

The catches: Outlook has to be installed and configured for the PST export step, although scanning and previewing work without it. It’s Windows only. There aren’t many public reviews yet. The two on G2 are positive, but both would like a more modern-looking interface. And like every tool here, it can only return what’s actually inside the OST.

Product page: EdbMails OST to PST Converter

2) Stellar Converter for OST

Stellar Converter for OST handles inaccessible, orphaned, encrypted and IMAP-account OST files. It finds the OST files configured on the machine by itself, lets you search for others, and shows a preview of the mailbox. Output can be PST, MSG, EML, RTF, HTML or PDF, and there are message filters plus an automatic split of large PST files at around 45 GB. You can also save the scan and load it later, which is handy if you want to scan on one computer and convert on another.

The edition you pick matters a lot here. Corporate ($79, shown as reduced from $99) covers converting a single file. Technician ($149) adds batch conversion, PST compacting and splitting, and direct export to live Exchange and Microsoft 365. Toolkit ($199) throws in tools for PST repair, merging, password recovery and restoring deleted emails. The vendor says licences come as a one-year subscription or lifetime, and that Corporate is a single-device licence.

The catches: the free demo lets you preview everything but won’t save converted data, so you can’t test a real export before buying. Batch conversion and direct migration both need the Technician edition. Supported systems are Windows 11, 10, 8.1 and 8, 64-bit. The vendor’s FAQ mentions roughly seven minutes per GB, which we’d read as a ballpark and not a promise.

3) Kernel OST to PST Converter

Kernel OST to PST Converter converts inaccessible, orphaned or damaged OST files and can run several files in one go. The vendor says there’s no file size or item limit. It has the longest list of output formats here: PST, EML, MSG, DBX and MBOX, plus single messages as PDF, TXT, RTF or HTML. It can also export directly to Microsoft 365, live Exchange Server, Gmail, Yahoo and other webmail accounts.

Filters cover item type, date range, folder, sender, recipient and subject. You can split the PST into sizes like 2 GB or 5 GB, decide whether deleted items come along, search the OST by keyword, and save a snapshot of a conversion to resume later. Deleted items show up in red in the preview. The trial exports up to 25 items per folder, the smallest allowance of the four. Third-party listings show pricing from $49, and the product page names Personal, Home, Corporate and Technician licence types, so check the buy page for the edition you actually need.

The catches: the product page doesn’t mention encrypted OST files, so if that’s your situation, ask the vendor before buying. It’s a Windows tool, and the vendor lists Outlook versions from Office 365 and 2024 back to older releases.

Product page: Kernel OST to PST Converter

4) Shoviv OST to PST Converter

Shoviv OST to PST Converter recovers and converts orphaned, corrupted, encrypted and healthy OST files, and it can also process NST (group storage) files. It saves to PST, MSG, EML, EMLX, HTML, vCard and vCal, and exports directly to Microsoft 365 and on-premises Exchange mailboxes, with mapping to primary, archive or shared mailboxes. There’s a preview before conversion, and the folder hierarchy is kept.

Two things stand out. It has an Outlook-independent mode as well as an Outlook-dependent one, so a straightforward conversion can run on a machine without Outlook. The vendor suggests the dependent mode for badly corrupted files. And its incremental export can pick up an interrupted job where it stopped and skip what’s already been transferred. You also get filters by date range, message class and folder, PST splitting by size, and the option to password-protect the output PST. The full version is listed at $49, and the trial converts up to 50 items per folder, the biggest allowance of the four.

The catches: the vendor’s specifications list Outlook Classic as a prerequisite for the OST recovery task, so read the mode descriptions closely to see which one fits your file. It runs on Windows only.

OST to PST Converter Feature Comparison

This table sticks to what each vendor’s product page says. “Not stated” means we couldn’t find it mentioned, not that the feature is missing.

OST to PST Converter Pricing Compared

These numbers come from the vendors’ own pages and public listings in September 2026. Prices move around and discounts come and go, so confirm the figure at checkout.

Don’t just compare the headline price. Look at what each edition actually unlocks. A cheaper edition without batch conversion or direct export can end up costing more once you have to upgrade.

Which Tool for Which Situation?

If the data is headed for a Microsoft 365 tenant and you’re moving more than a handful of mailboxes, our guide to the best Office 365 migration software covers tools built for that job.

How to Convert OST to PST Step by Step

The screens differ from tool to tool, but the flow is nearly always the same:

1. Close Outlook and copy the OST to a working folder. Make sure there’s enough free disk space for the PST that’s about to be created.
2. Install the converter on a Windows machine and open it.
3. Add the OST file. Browse to your copy, or use the tool’s search option if you’re not sure where the file is.
4. Scan and preview. Let the scan finish, then open a few folders and check that messages, attachments and dates look right.
5. Choose what to convert. Whole folders or single items. Add date or sender filters if you only need part of the mailbox.
6. Pick PST as the output. If the mailbox is big, set a split size so you don’t end up with one huge file.
7. Start the export and save the PST somewhere you’ll be able to find it again.
8. Open the PST in Outlook through File, Open & Export, Open Outlook Data File. Compare folder item counts with the preview, then spot-check a few attachments and calendar entries.

Try it on a small sample with the free trial first. If the sample looks right, buy the licence and run the full file.

Practical Tips Before You Convert

• Don’t work on your only copy. Keep the original OST untouched, even after a successful export.
• Download from the vendor’s own site. Skip mirror sites and repackaged installers.
• Check disk space. The PST can end up as big as the OST, and a split export needs room for every part.
• Test something representative. Pick a folder with attachments, plus a calendar and a few contacts.
• Check the result afterwards. Compare item counts, look at some dates and open a few attachments.
• Read the licence. Note how many machines it covers, how long it lasts and whether upgrades are included.

A Note on Ratings

Some vendor pages show star ratings from hundreds of reviews, while third-party sites show far fewer, and the numbers don’t line up. Since they come from different platforms with different review volumes, we chose not to put them side by side in a table. If you’ve shortlisted a tool, read a few recent independent reviews. Comments about your exact situation are worth more than the star average.

And honestly, the best way to decide is to test. All four vendors offer some kind of free version, and a short export from your own file will show you how the tool handles your data.