“Which Outlook do I have” has more than one answer now. On a Windows PC it can be classic Outlook, the new Outlook for Windows, or just Outlook in a browser, and the version number lives in a different place in each. In this guide, I’ll show how to tell them apart in a few seconds, and then how to read the version and build.
Quick Answer: If your Outlook window has a File tab, it is classic Outlook, and the version is under File > Office Account > About Outlook. If it has a Settings gear at the top right and no File tab, it is new Outlook, and the version is under Settings > General > About Outlook. On a Mac, use Outlook > About Outlook.
New Outlook or Classic Outlook: Which One Is Open?
Look at the top of the window first. Microsoft’s own what version of Outlook do I have page uses the same test.
- Classic Outlook for Windows: a File tab, no Settings gear. The classic app also has a Try the new Outlook switch at the top right, if it is turned on for you.
- New Outlook for Windows: a Settings gear at the top right and ribbon tabs like Home, View and Help. No File tab.
- Outlook on the web: it runs in a browser. After you sign in, check the address. outlook.office.com or outlook.office365.com is Outlook on the web for a work or school account. outlook.live.com is Outlook.com for a personal account.
- Outlook for Mac: the Outlook menu in the Mac menu bar, with an About Outlook entry.
If both Windows apps are installed, the Start menu lists them as Outlook (the new one) and Outlook (classic). They are two separate apps, so the new Outlook is not an update of the classic one, and you can keep both for a while.
One more name to know about. The old Mail and Calendar apps in Windows stopped working for email on 31 December 2024, and Microsoft replaced them with the new Outlook. If you see an app called Mail, it is not what you want.
Find the Version in Classic Outlook for Windows
- Open Outlook and click File.
- Click Office Account (on some installs it is called Account).
- Under Product Information, click About Outlook.
You get two things. The line under the About Outlook button shows the version and build, and the window that opens shows the same number plus 32-bit or 64-bit.
The same page also shows the product name. “Microsoft 365 Apps for business” means a subscription. “Outlook 2024” or another year means you bought Office once. That difference matters for support dates, which are further down.
Find the Version in New Outlook for Windows
- Click the Settings gear at the top right.
- Go to General.
- Click About Outlook.
If you want to go back to the classic app, see how to change Outlook to classic view.
Find the Version on Mac and on Mobile
On a Mac, click Outlook in the menu bar, then About Outlook. A Microsoft 365 subscription does not show a year here, only the version number.
On the Outlook mobile app, open Settings and go to Help & Feedback, then scroll to the bottom.
How to Read the Version and Build Number
A classic Outlook line looks like this: Version 2609 (Build 20430.20146).
- 2609 is the release in year and month form (YYMM). Read it as 26 for the year and 09 for the month.
- 20430.20146 is the build. The part after the dot changes with each update inside that release.
Your numbers will differ from this example. The version line also names the install type (Click-to-Run, for example) and the update channel. When you ask IT or Microsoft Support for help, give them the whole line. The year alone is not enough.
If a user phones the helpdesk, ask for that line plus the answer to the first question in this post (File tab or gear). Those two things tell you almost everything about which fixes apply. A step written for classic Outlook will not work on new Outlook, and the reverse is also true.
Why the Office Year Does Not Match Your Outlook
Outlook with a year in its name comes from a one-time purchase, and the year decides when support ends. A Microsoft 365 subscription shows no year at all, because it keeps getting updates while the subscription is active.
- Office 2016 and Office 2019: support ended on 14 October 2025.
- Office 2021: support ends on 13 October 2026, according to Microsoft’s Office 2021 lifecycle page.
- Office 2024: support runs until 10 October 2029.
Old Outlook builds keep running after support ends, but they stop getting security fixes. If your About page says 2019 or older, plan the move.
Why the “Try the New Outlook” Switch Can Be Missing
On a work or school account, the switch may simply not be there. Microsoft lets admins hide or disable the toggle by policy. The side-by-side page from Microsoft, run new Outlook and classic Outlook side by side, describes the toggle. If yours is missing, ask IT before reinstalling anything.
There are practical reasons to wait. Microsoft’s comparison page still lists COM add-ins as unsupported in new Outlook, and PST files and offline use as only partly available. If you rely on a local archive, read where the Outlook PST file is stored before you switch.
What Happens to Classic Outlook Next
Classic Outlook is not going away tomorrow. Microsoft’s stages of migration to new Outlook says existing classic installs, perpetual and subscription, stay supported until at least 2029. The later stages, where new Outlook is on by default and then cannot be reversed, come with at least 12 months of notice for managed enterprises.
FAQ
How do I check my Outlook version without opening Outlook?
On the web, the address bar tells you the service (see the list above). For desktop Outlook I know of no reliable shortcut, so open the app and use About Outlook. That is the place Microsoft documents.
Is Outlook 2024 the same as new Outlook?
No. Outlook 2024 is a classic desktop app you buy once, with support until 10 October 2029. New Outlook is a separate app, not a version of the classic one.
Why does my Outlook not show a year?
You have a Microsoft 365 subscription, which has no year in its name. Read the version and build instead.
If you are about to troubleshoot something, note the File tab or gear and the full version line first. If you want to see how big your mailbox is next, here is how to see your Outlook mailbox size in each client.
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