What you need before you start

Before you install Microsoft Office, you need three things: a Microsoft account (free to create), a device that meets the system requirements, and either a product key or an active Microsoft 365 subscription. If you bought Office as a one-time purchase, you have a product key. If you pay monthly or yearly, you have a subscription.

Check your device's operating system first. Microsoft Office runs on Windows 10 or later, or macOS 10.10 or later. If you have an older device, installation will fail. You also need at least 4 GB of RAM and 3 GB of free hard drive space for the full suite.

Know which version you have. If someone gave you a product key card or email, you own a one-time license. If you pay a monthly bill to Microsoft, you have a 365 subscription. The installation process differs slightly between the two.

Key Takeaways

  • You must sign in with a Microsoft account during installation, even if you already own a product key.
  • Download Office directly from Microsoft's website (office.com) rather than from other sites to avoid malware.
  • The full installation takes 15 to 30 minutes depending on your internet speed and device performance.
  • If installation fails, restart your device and check that Windows or macOS is fully updated before trying again.
  • One product key works on one device only; a 365 subscription lets you install on up to five devices at once.

Creating or signing into your Microsoft account

Go to account.microsoft.com and either sign in if you already have an account, or select "Create one" to make a new account. You need a working email address and a password. Microsoft will send a verification code to that email — check your inbox and spam folder.

If you have a product key, add it to your account now. Sign in, go to "Services & subscriptions," and select "Redeem a product key." Type the key exactly as it appears on your card or email, including hyphens. Microsoft will attach it to your account permanently.

Write down your email and password somewhere safe. You will need both during installation, and you may need them again if you reinstall Office later or move it to a different device.

Downloading Office from Microsoft's website

Open a web browser and go to office.com. Sign in with the Microsoft account you just created or verified. You will see a "Install Office" button or a list of your subscriptions.

If you see "Install Office," click it. If you see a subscription listed (like "Microsoft 365 Personal"), click "Install" next to it. Microsoft will download a small installer file to your device — usually called "OfficeSetup.exe" on Windows or "Microsoft Office Installer" on Mac.

Do not download Office from any other website. Fake versions exist on third-party sites and can contain malware. The real installer always comes from office.com or from a link in an email from Microsoft itself.

Running the installer on Windows

Find the file you downloaded — usually in your Downloads folder. Double-click "OfficeSetup.exe" to start the installer. Windows may ask for permission to make changes to your device; click "Yes."

The installer will show a progress bar and download the full Office suite to your device. This step takes 10 to 20 minutes depending on your internet speed. Do not close the window or restart your device while this is happening.

When the download finishes, the installer will automatically install Word, Excel, PowerPoint, Outlook, and other Office programs. You will see another progress bar. When it reaches 100%, a screen will say "You're all set." Click "Close."

Open the Start menu, type "Word" or "Excel," and click the result to verify the installation worked. If the program opens, installation is complete.

Running the installer on Mac

Find the file you downloaded — usually in your Downloads folder. Double-click "Microsoft Office Installer" to open it. A window will appear asking you to drag the Office icon into the Applications folder.

Click and hold the Office icon, drag it to the Applications folder icon shown in the same window, and release. macOS will copy Office to your Applications folder. This takes 10 to 20 minutes.

When the copy finishes, open Finder, click Applications in the sidebar, and look for Microsoft Office or individual programs like Word and Excel. Double-click Word or Excel to open it. The first time you open an Office program, it may take a minute to start while it finishes setting up.

When the program opens, sign in with your Microsoft account. This activates your license. After you sign in once, you will not need to sign in again on that device.

What to do if installation fails or gets stuck

If the installer stops responding or shows an error, close it completely. Restart your device. Then check that your operating system is fully updated — Windows and Mac both release updates that Office needs to run.

On Windows, open Settings, click "Update & Security," and select "Check for updates." On Mac, open System Preferences, click "Software Update," and install any available updates. Restart your device again and run the installer a second time.

If you still see an error, uninstall Office completely and try again. On Windows, open Settings, click "Apps," find Microsoft Office in the list, click it, and select "Uninstall." On Mac, open Finder, go to Applications, right-click Microsoft Office, and select "Move to Trash." Then download the installer again from office.com and run it.

If the problem continues, your device may not meet the system requirements. Check that you have Windows 10 or later (or macOS 10.10 or later), at least 4 GB of RAM, and 3 GB of free hard drive space. If you are below these minimums, Office will not install.

Signing in for the first time and activating your license

When you open Word, Excel, or another Office program for the first time, a sign-in screen will appear. Enter the email and password for your Microsoft account. Do not create a new account — use the same one you used to download Office.

After you sign in, Office will activate your license. This means Microsoft's servers confirm that your account owns a valid product key or subscription. Activation usually takes a few seconds but can take up to 24 hours in rare cases.

While activation is pending, you can still use Office. You will see a yellow banner at the top of the window saying your product is not activated yet. Once activation completes, the banner disappears and you have full access to all features.

Frequently Asked Questions

Can I install Office on more than one device?

It depends on what you own. A one-time product key works on one device only. If you buy a Microsoft 365 subscription, you can install Office on up to five devices at the same time and use it on all of them. Check your account at account.microsoft.com under "Services & subscriptions" to see how many devices you have left.

What if I forgot my Microsoft account password?

Go to account.microsoft.com and click "Can't access your account?" Follow the steps to verify your identity using your phone or backup email. Microsoft will let you create a new password. Once you reset it, use the new password during Office installation.

Do I need internet to use Office after I install it?

You need internet to sign in and activate your license the first time. After that, Word, Excel, and PowerPoint work offline. Outlook and OneDrive work better with internet, but you can still read and compose emails offline. Subscription features like cloud storage and collaboration require internet.

Why does Office ask me to sign in every time I open it?

This usually means your device did not complete activation. Restart your device and open Office again. If the sign-in screen appears every time, go to account.microsoft.com, check that your product key or subscription is still attached to your account, and contact Microsoft support if it is missing.

Can I move Office to a different device later?

Yes. Uninstall Office from the old device first, then download and install it on the new device using the same Microsoft account. If you have a one-time product key, you can only use it on one device at a time, so uninstalling from the old device frees it up for the new one. If you have a 365 subscription, you can install on up to five devices without uninstalling from the others.