Install Office 2021 on a PC or Mac

This guide takes you from the product key in your order to a working copy of Office 2021. There are two routes, and your edition picks the route for you. Once Office is installed, continue with Activate Office 2021.

What you received

Every Office 2021 order contains a product key of 25 characters. It looks like XXXXX-XXXXX-XXXXX-XXXXX-XXXXX. It arrives in your order confirmation email, and it is also stored in your Lizensa account under My Library.

Which route you take depends on the edition:

Professional Plus and Standard are delivered as Microsoft's volume-licensed editions, Office LTSC Professional Plus 2021 and Office LTSC Standard 2021. Professional Plus contains Word, Excel, PowerPoint, Outlook, OneNote, Access, Publisher and Skype for Business. Standard has the same apps except Access and Skype for Business. Microsoft no longer includes the Teams app with Office LTSC 2021.

Home & Student 2021 contains Word, Excel, PowerPoint and OneNote. Home & Business 2021 adds Outlook. Microsoft licenses both for one PC or Mac.

End of support. Microsoft ended support for Office 2021 and Office LTSC 2021 on 13 October 2026. There is no extension. Microsoft says the apps may continue to work, but it no longer releases security fixes, bug fixes or software updates for them, and it no longer gives technical support for them.

What your computer needs

• Windows: Microsoft lists Windows 11 for Office 2021. Office LTSC 2021 also runs on Windows 10 LTSC 2019 and 2021, Windows 11 LTSC 2024 and Windows Server 2019, 2022 and 2025.
• Mac: one of the three latest macOS versions, 4 GB of RAM and 10 GB of free disk space.
• PC hardware: a two-core processor at 1.1 GHz or more, 4 GB of RAM, 4 GB of free disk space and a screen of at least 1280 x 768.
• Rights: an administrator account on the computer.
• Internet: retail editions need it to redeem the key, to activate and, from time to time, to stay activated. The ISO installs without a connection.

Get the software

Home & Student and Home & Business: redeem your key with Microsoft

You download nothing from us for these editions. Microsoft holds the installer and ties your licence to a Microsoft account.

1. Open office.com/setup in your browser.
2. Sign in with your Microsoft account. If you have none, create one on the same page.
3. Type the product key from your order.
4. Follow the remaining prompts until Microsoft confirms that Office is added to your account.

From now on, Office 2021 is listed in that Microsoft account. Write down which account you used. Every future reinstall starts from there, and you will not be asked for the key again.

Professional Plus and Standard: download the ISO from your library

Your download link is in your order email and in your account.

1. Sign in to your Lizensa account and go to My Library.
2. Find your Office 2021 product and select Download.
3. Keep the file in a folder you can find again, for example Downloads.

The ISO is a disc image of about 2.0 to 2.3 GB. It contains the 64-bit edition of Office in one language. We keep each edition in 33 languages. Your library offers the language of the shop you ordered from, or English (en-US) where that language is missing. If you need another language, ask our support before you install.

Each download link is created at the moment you select Download and expires after 15 minutes. That is no problem: if the transfer stops, select Download again for a new link.

Install

Before you start, remove any older Office from the computer. On Windows, open Settings > Apps > Installed apps, find the old Office and select Uninstall. Your documents stay where they are.

Home & Student and Home & Business on Windows

1. Go to account.microsoft.com/services and sign in with the account from office.com/setup.
2. Under Services & subscriptions, find Office 2021 and select Install.
3. Open the setup file. Edge offers Run, Chrome Setup and Firefox Save File.
4. When Windows asks "Do you want to allow this app to make changes to your device?", select Yes.
5. Office now downloads and installs. Leave the computer online.
6. When "You're all set! Office is installed now" appears, select Close.

Office installs as 64-bit unless a 32-bit Office is already on the PC.

Home & Business 2021 for Mac

1. Sign in at account.microsoft.com, find Office and start the download.
2. In Finder, open Downloads and double-click Microsoft Office installer.pkg. The name can differ slightly.
3. Select Continue, read the licence agreement, select Continue again and then Agree.
4. Select Install. Enter your Mac password when asked, then select Install Software.
5. Select Close when the installer reports it has finished.

More detail for macOS is in Office for Mac.

Professional Plus and Standard from the ISO

Save your work and close every Office app first. Setup closes running Office apps without asking.

1. In File Explorer, right-click the ISO and select Mount. A new drive appears, for example F:.
2. Open that drive. It holds setup.exe, configuration.xml, install.cmd and a folder named Office.
3. Right-click install.cmd and select Run as administrator. Confirm with Yes.
4. The Office installer window opens and shows its progress. You are not asked to accept terms or to choose apps.
5. When the window says the installation is done, close it. Then right-click the new drive and select Eject.

install.cmd hands the settings in configuration.xml to Microsoft's Office Deployment Tool. Starting setup.exe with a double-click does nothing useful, because the tool needs those settings. The same command, typed into Command Prompt as administrator on the mounted drive, is:

setup.exe /configure configuration.xml

Setup reads only the files on the ISO, so the computer can stay offline during installation.

Activate

After installation comes activation. How it works depends on the route:

• Home & Student and Home & Business: start Word, sign in with your Microsoft account if asked and accept the licence agreement. On a Mac, select Get Started in the What's New window.
• Professional Plus and Standard: the ISO carries no product key. Office starts with Microsoft's generic key for company activation servers (KMS). You replace it with your own key: in Word, open File > Account, select Change Product Key under Product Information, type the key and select Activate. Or run these two commands in Command Prompt as administrator:

cscript "C:\Program Files\Microsoft Office\Office16\OSPP.VBS" /inpkey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
cscript "C:\Program Files\Microsoft Office\Office16\OSPP.VBS" /act

By default, only an administrator can activate a volume edition with a MAK. Every option, with its error messages, is in Activate Office 2021.

PC without internet

The ISO installs offline, but online activation of a volume key needs internet. Activate by telephone instead:

1. Install your key with the /inpkey command above. That works offline.
2. Open Word. When the Activation Wizard appears, select "I want to activate the software by telephone" and then Next.
3. Choose your country or region and call the number shown. Microsoft's activation centres page lists the volume licensing numbers too.
4. Give the installation ID from the wizard, type the confirmation ID you receive and select Next.

The command-line version is under telephone activation in the activation guide.

Check it worked

1. Select Start, type Excel and open it.
2. Select File > Account.
3. Read the name under Product Information. It should match your order, for example Office LTSC Standard 2021 or Office Home & Business 2021.

Check that Word, Excel and PowerPoint all start. With Professional Plus, Access and Publisher should be in the Start menu as well. If the edition is wrong, uninstall Office and install again with the download that matches your order.

For Professional Plus and Standard, Command Prompt as administrator also shows the licence state once you have activated:

cscript "C:\Program Files\Microsoft Office\Office16\OSPP.VBS" /dstatus

The block for Office 21 should read ---LICENSED---. On a Mac, the checks are described in Office for Mac.

If something goes wrong

Excel opens, but a yellow bar says Office is unlicensed or not activated. Office is installed but not yet activated. A volume edition without your key runs in a grace period until you activate it. See error 0x4004F00C and the activation guide.

The key from your order is refused as invalid. Check that the installed edition matches your order: a Standard key does not activate Professional Plus, and a retail key does not activate an LTSC edition. If the edition matches, send our support your order number. See error 0xC004F050.

Activation reports 0xC004F074. Office is still trying to reach a company KMS server with its generic key. Enter your own key as shown above and activate again. See error 0xC004F074.

A command answers "Access denied" or 0x80070005. Command Prompt was not started as administrator. Close it, right-click Command Prompt, select Run as administrator and repeat the command. See error 0x80070005.

Nothing happens after you double-click setup.exe. That file needs configuration.xml. Run install.cmd as administrator instead.

Setup stops and names another Office product. Look for an older Office version, or a 32-bit Office, Visio or Project, that is still installed. Remove it, restart the computer and run setup again. Microsoft does not allow 32-bit and 64-bit Office products on the same PC.

Windows cannot mount the ISO. Get a fresh link from your library and download the file again. If mounting still fails, send our support the exact error message.

office.com/setup says "This product key has already been used". The key is already in a Microsoft account. Sign in with that account at account.microsoft.com and install from Services & subscriptions.

office.com/setup says "This product key isn't meant for your region". Microsoft expects a key to be redeemed in the country or region where it was purchased. Do not try other keys. Send our support your order number and the exact message.

Still stuck? Contact our support with your order number, your edition and the exact message you see.