How to Install and Activate Office 2016, 2019, 2021 and 2024

Installing Office goes smoothly when the installer matches the key. Most activation problems come from installing the wrong edition (for example a Microsoft 365 trial when the key is for Office 2021 Pro Plus), so this guide starts with that check and then covers installation and activation for Office 2016, 2019, 2021 and 2024 on Windows and Mac.

Which Office edition do you have?

Look at the product name on your order before you download anything. The edition decides how you install and activate.

Pro Plus includes Word, Excel, PowerPoint, Outlook, OneNote, Access and Publisher. Home & Business includes Word, Excel, PowerPoint and Outlook (plus OneNote on some versions), and is licensed for commercial use.

Before you install Office

1. Remove other Office versions. Go to Settings > Apps and uninstall Microsoft 365, any Office trial and older Office versions you no longer need. Restart the PC.
2. Check Windows. Office 2021 and 2024 run on Windows 10 and Windows 11. Keep Windows up to date before you install.
3. Choose 64-bit or 32-bit. 64-bit is the right choice for most people. You cannot mix 32-bit and 64-bit Office on one PC.
4. Have your key ready. It appears on screen and in your email after payment, and in My Account > Orders on our site.

How to install and activate Office Pro Plus (2016, 2019, 2021)

Pro Plus is activated with the product key inside Office.

1. Run the Office installer for the exact edition and version on your order (for example Office 2021 Professional Plus).
2. Wait for the installation to finish. Office 2019 and 2021 install as Click-to-Run and download files during setup, so stay online.
3. Open Word.
4. If you are asked to sign in or activate, choose to enter a product key.
5. Enter the 25-character key and click Continue or Activate.
6. Office activates online. If it cannot, choose telephone activation and follow our guide to activating Office by phone.
7. Check File > Account. It should say Product Activated with the correct edition name.

IT admins deploying Pro Plus to several PCs can use Microsoft's Office Deployment Tool with a configuration file, then add the key with cscript ospp.vbs /inpkey: followed by the key, and activate with cscript ospp.vbs /act.

How to install and activate Office Home & Business on Windows

Home & Business keys are linked to a Microsoft account the first time you use them.

1. Go to setup.office.com.
2. Sign in with the Microsoft account you want the license tied to, or create one.
3. Enter the 25-character product key and choose your country or region and language.
4. Once the key is redeemed, go to your Microsoft account's Services & subscriptions page and select Install.
5. Run the downloaded installer.
6. Open Word and sign in with the same Microsoft account. Office activates automatically.

The license stays on your Microsoft account. If you reinstall Office later, sign in to the same account and install it again. You do not need to enter the key a second time.

How to install and activate Office for Mac

Office 2021 Home & Business for Mac works the same way as the Windows retail editions.

1. Redeem the key at setup.office.com with your Microsoft account.
2. Download the installer package from Services & subscriptions.
3. Open the downloaded .pkg file and follow the steps. Enter your Mac password when asked.
4. Open Word and select Sign in. Use the same Microsoft account.
5. Word confirms the license and activates all the apps.

Office for Mac is licensed separately from Office for Windows. A Windows key will not activate Office on a Mac, and a Mac key will not activate Office on Windows.

Common errors when installing or activating Office

Wrong edition installed

This is the most common problem. Office installs fine but rejects the key, or keeps asking you to sign in to Microsoft 365. Check File > Account. If the name under Product Information does not exactly match your order (version and edition), uninstall it, restart, and install the matching edition.

Microsoft 365 keeps asking you to sign in

A preinstalled Microsoft 365 trial is still present. Remove every Office and Microsoft 365 entry from Settings > Apps, restart, reinstall your edition, and enter the key again.

32-bit and 64-bit conflict

Setup stops because another Office app of the other bit version is installed, such as Visio or Project. Uninstall it, or install Office in the same bit version as the existing app.

Key already used or blocked

Online activation reports that the key has been used. Try telephone activation first. If that fails, contact us. Every key we sell is a genuine Microsoft product key with guaranteed activation, and if it will not activate we send a working replacement free of charge.

Need to swap the key

If you entered the wrong key, see our guide to changing the Office product key.

Office support end dates

Microsoft publishes a fixed support period for each perpetual Office version. After that date the software keeps working, but Microsoft no longer ships security updates for it.

For a longer view of the options, read our comparison of Office 2021, Office 2024 and Microsoft 365.

Need help?

Our free tech support runs 7 days a week. Open a ticket at /support or call +1-888-470-5516 with your order number and the message you see, and we will stay with you until Office is installed and activated.