How do I move a Gmail Takeout export into Outlook?

Unzip the Takeout download and drop the .mbox file from its Mail folder here ("All mail Including Spam and Trash.mbox"). Gmail puts every message in that one file with its labels; each message goes into the PST folder of its first label, so Work, Receipts and your other labels come out as folders, with Inbox and Sent for the rest. Then open the PST in Outlook.

Where does Thunderbird keep its mbox files?

In the profile's Mail or ImapMail folder: in Thunderbird, Help, Troubleshooting Information, Profile Folder, Open Folder. Each mail folder is a file without an extension (Inbox, Sent, Archives), beside an .msf index file that is not needed. Drop the files you want, or the whole account folder, and each becomes a folder in the PST.

Will a very large mbox file work?

Yes, up to the 3.3 GB one PST file can hold - a little more mbox than that, as attachments take less room in a PST than in an mbox, where they are stored as text. If it reaches the limit, the page finishes that PST and offers a button to put the rest into a second one. Chrome and Edge write the PST straight to disk, so memory is not the limit; other browsers build it in memory, which suits a gigabyte or so.

Do Gmail labels and stars carry over?

Labels become folders, one per message (a message with several labels goes in the folder of the first). Read and unread carry over. Stars and Important markers do not: Outlook has no place for them in a PST made this way.

Stays on your computer Needs a desktop or laptop browserHow this works

Convert MBOX to PST

Turn an mbox mailbox - Gmail’s Takeout export, Thunderbird’s folder files, an Apple Mail export - into an Outlook data file (.pst), each mailbox or Gmail label as its own folder. Free, any size, and nothing is uploaded.

Drag & drop .mbox files or a mail folder here, or browse

Gmail Takeout .mbox · Thunderbird folder files · Apple Mail .mbox · several at once · nothing is uploaded

Or : its subfolders become folders in the PST.

About converting MBOX to PST

An .mbox file is a whole mail folder in one file: every message one after another. Gmail's Google Takeout export is one, Thunderbird keeps each of its folders as one (a file with no extension, named Inbox, Sent and so on), and Apple Mail exports mailboxes as them. Outlook for Windows cannot open or import any of them - it reads .pst files - and the converters sold for the job charge per mailbox or stop after a few dozen messages in their free version.

This page reads the mailbox and writes the PST in your browser. Every message keeps its sender, recipients, date, subject, Message-ID, plain and HTML body, attachments and pictures, and its read or unread state where the mailbox records it (Gmail's Unread label, Thunderbird's status header). A big Takeout file is scanned in slices for where each message starts, never loaded whole, and each message is read and written one at a time, so a mailbox of many gigabytes converts without filling the computer's memory. It is free to use, with no account and no upload limit, and it runs entirely in your browser: nothing is uploaded, and while the page stays open, a feature you have already used keeps working offline.

What you can do

Convert a Gmail Takeout .mbox to PST, each message in the folder of its Gmail label
Convert Thunderbird folder files, several at once, each into a folder of the same name
Convert Apple Mail exports (the Inbox.mbox folders Mailbox, Export Mailbox makes), named after the mailbox
Convert mailboxes of many gigabytes: the file is read in slices, and the PST is written straight to disk in Chrome and Edge
Keep attachments, pictures in the body, HTML formatting, read and unread, and the original internet headers
Add loose .eml or .msg files, or an Outlook for Mac .olm, to the same PST

How to convert an MBOX file to PST

Drop the .mbox file, several of them, or the folder they are in onto the page.
Check the folders and the number of emails found, and name the PST.
Press Make the PST file. In Chrome and Edge, choose where to save it first; it is written there as it goes.
In Outlook, choose File, Open & Export, Open Outlook Data File, and pick the PST.

Questions

How do I move a Gmail Takeout export into Outlook?: Unzip the Takeout download and drop the .mbox file from its Mail folder here ("All mail Including Spam and Trash.mbox"). Gmail puts every message in that one file with its labels; each message goes into the PST folder of its first label, so Work, Receipts and your other labels come out as folders, with Inbox and Sent for the rest. Then open the PST in Outlook.
Where does Thunderbird keep its mbox files?: In the profile's Mail or ImapMail folder: in Thunderbird, Help, Troubleshooting Information, Profile Folder, Open Folder. Each mail folder is a file without an extension (Inbox, Sent, Archives), beside an .msf index file that is not needed. Drop the files you want, or the whole account folder, and each becomes a folder in the PST.
Will a very large mbox file work?: Yes, up to the 3.3 GB one PST file can hold - a little more mbox than that, as attachments take less room in a PST than in an mbox, where they are stored as text. If it reaches the limit, the page finishes that PST and offers a button to put the rest into a second one. Chrome and Edge write the PST straight to disk, so memory is not the limit; other browsers build it in memory, which suits a gigabyte or so.
Do Gmail labels and stars carry over?: Labels become folders, one per message (a message with several labels goes in the folder of the first). Read and unread carry over. Stars and Important markers do not: Outlook has no place for them in a PST made this way.

To read an mbox without converting it, open it in the MBOX Viewer. Single emails, folders of .eml and .msg files and Apple Mail .emlx files go through the EML to PST Converter; the result opens in the PST Viewer too.