If your organization has transitioned from an MBOX-supporting email client like Apple Mail or Mozilla Thunderbird to Outlook, or you just want to access MBOX file data in the Outlook client, you’d need to convert the MBOX file to Outlook-importable PST format.
The simplest way to do this is to use an online MBOX converter utility. This is because an online MBOX converter lets you convert your mailbox file using a web browser, without relying on downloading or installing software, for free. Hence, it becomes suitable for users looking for quick results. But if you search on the internet for “online MBOX converter”, you will not find many free utilities that work online. There are only a handful of them available.
In this article, we will take a look at 3 free MBOX to PST converter services listed below:
Best Free MBOX to PST Converter Tools in 2026
We have selected 3 web-based MBOX to PST converter utilities that are free to use. These are:
- Stellar MBOX to PST Converter Online
- Aspose MBOX to PST Converter
- FILEFORMAT MBOX to PST Converter
We have tested each of these online MBOX utilities and selected them for their ease of use, speed, and accuracy of the resultant PST file. Here’s a detailed look at them.
Stellar Online MBOX to PST Converter
The first free MBOX to PST converter utility we tested is the online MBOX to PST converter by Stellar. It is a simple and straightforward web-based utility that lets you convert a single MBOX file to PST format for free. The only condition here is that the mailbox archive file should be of size 100MB or less. It supports .mbox files of many popular email clients, including Gmail, Apple Mail, and Mozilla Thunderbird. And, not just Windows; you can even use it on a Mac or a Linux PC to convert your MBOX files on the go. No additional software installation required.
Along with convenience, the online MBOX converter by Stellar is also designed to produce accurate results. It ensures that the resultant mailbox file (PST) retains all the mailbox items in the same sequence as in the source MBOX file.
This online utility also has a Premium edition of this online utility, which costs $19.99 and lets you convert up to 5 MBOX files of size ≤5GB with ease. This should suffice most users’ needs.
Pros:
- Converts an MBOX file of ≤100MB for free
- Simple 3-step mailbox conversion: Upload > Convert > Download
- Doesn’t require Outlook to be installed
- Ensures data privacy by automatically deleting converted mailbox files from the server after 24 hours of conversion
- Works via web browser on Windows, Mac, and Linux systems
Cons:
- Free version converts just 1 MBOX file of size not more than 100MB
- No individual mailbox item preview available
- Premium edition also limits MBOX file conversion to up to 5 files
Aspose MBOX to PST Converter
Aspose has a slew of online utilities for different purposes. One such is its online MBOX converter. It is another simple-to-use service that lets you convert your MBOX file to Outlook-importable PST format in no time. You can use it without even registering or creating an account on it, though for a very small MBOX file of size less than 1MB. If you register on its website, you can upload and convert MBOX files of size not larger than 5MB to PST for free.
The given file size limits for the free editions are barely enough for even casual users. With a 1MB MBOX file, you won’t be able to convert more than approximately 20 text-based email messages, and 80 text-based email messages after registering, for free.
It also has a batch conversion feature, which lets you select multiple MBOX files and convert them to PST format in one go. Free (unregistered) users can only convert up to 2 MBOX files at a time, while Registered users can select up to 10 MBOX files.
Pros:
- No registration required to convert small (≤1MB) MBOX files
- The resultant PST file is available to download for 24 hours after the conversion
Cons:
- Extremely small file size limit makes the free editions unsuitable for users with large mailboxes (>5MB)
- No file preview option
- Batch processing merges emails from multiple MBOX files into a single file; mailbox hierarchy is lost
FILEFORMAT MBOX to PST Converter
The FILEFORMAT MBOX to PST Converter is the final online MBOX converter that we tested. It has a modern UI, which makes it very user-friendly. Just like the two others, it conveniently converts MBOX to PST files for free. But what makes it stand out is that it can also convert MBOX files to other file formats like EML, EMLX, TML, ICS (Calendar file only), MHTML, MSG, etc. Moreover, it makes MBOX to PST file conversion simple for users who store their files in cloud storage. This allows users to use MBOX files directly from their Dropbox or Google Drive accounts and convert them to PST or any other file format without any hassle. There is a unique feature to this service that lets users sort the uploaded files alphabetically.
Free users can convert 5 MBOX files, each having a size of 10MB or less. Its PAID versions are offered as subscriptions that allow you to convert multiple or large MBOX files. The Basic version costs $5/month and can process 15 files, each of size ≤25MB, per day. At the top is the Premium version that costs $55/year and can convert an unlimited number of MBOX files with no limits.
Pros:
- Fast MBOX file upload and conversion
- Allows users to upload files from Dropbox or Google Drive
- Multiple options to save the MBOX file data
- Sort the uploaded files in Alphabetical order.
Cons:
- Occasional errors while converting MBOX to PST format (could be due to incompatible file selected or some other issue)
- Subscription-based higher tiers
Quick Comparison of the Free MBOX to PST Converters
Here’s a quick comparison of the three online MBOX converters that we tested.
| Online MBOX Converters | Stellar Online MBOX to PST Converter | Aspose MBOX to PST Converter | FILEFORMAT MBOX to PST Converter |
| File Size Limit | ≤100 MB for Free (Registered users), ≤5 GB for Premium users | 1 MB for Free (Unregistered users) 5 MB for Registered users 50 MB for Premium users Custom file size for Business users |
10 MB/file for Free 25 MB/file for Basic No file size limit in Premium |
| No. of Files/Uses | Free – 1 Premium – up to 5 |
Unregistered – 5 Registered – 10 Premium – Unlimited Business – Custom |
Free – 5 Files Basic – 15 Files/day Premium – Unlimited Files/day |
| File Saving Options | PST | PST | EML, EMLX, TML, ICS (Calendar file only), PST, MHTML, MSG, etc. |
| Batch Conversion | No | Unregistered – 2 Registered – 10 Premium – 50 Business – Custom |
No |
| Price | Free Premium – $19.99 |
Unregistered Registered – Free Premium – $4/Month or $7/Year Business – Custom |
Free Basic – $5/Month Premium – $55/Year |
Final Verdict
Out of all three free MBOX to PST converters, the Stellar Online MBOX to PST converter lets you convert the maximum amount of email messages (100MB) for free. The other two online MBOX converters don’t allow you to process an MBOX file of this size for free. Their file size limits are extremely low, thus making their free editions unsuitable. Therefore, the Stellar Online MBOX to PST converter is the best free MBOX to PST converter available.
Additionally, Stellar also has a dedicated desktop-based MBOX to PST converter – Stellar Converter for MBOX – which can convert MBOX files to PST without any restrictions. You can use it to verify each mailbox item, save selected items as MSG or EML files, or directly export MBOX to an Outlook profile.