What you need before you start
Microsoft 365 (formerly called Office 365) is a subscription service that gives you access to Word, Excel, PowerPoint, Outlook, and other programs. Before you install it, you need a Microsoft account and an active subscription — either a personal plan like Microsoft 365 Personal, a family plan like Microsoft 365 Family, or a work account your employer provides.
Check your computer's operating system first. Microsoft 365 runs on Windows 10 or later, or macOS 10.10 or later. If you have an older machine, you may not be able to install the current version. You also need at least 4 GB of RAM and a few gigabytes of free disk space for the installation files.
If you already have an older version of Office installed (like Office 2016 or Office 2019), you can keep it or remove it before installing Microsoft 365. The installer will usually handle this, but removing the old version first prevents conflicts.
Key Takeaways
- You need a Microsoft account and an active Microsoft 365 subscription before you can install the software.
- Go to account.microsoft.com, sign in, and select Install Office to read the installer for your operating system.
- Run the installer file and let it complete — the process usually takes 10 to 20 minutes depending on your internet speed.
- After installation, open any Office app and sign in with your Microsoft account to set up your subscription.
- If installation fails, restart your computer and try again, or check that your account has an active subscription.
How to read the installer on Windows
Go to account.microsoft.com in your web browser and sign in with the Microsoft account connected to your subscription. Once you are signed in, look for a section labeled "Your Microsoft 365" or "Subscriptions" — the exact name changes depending on which version of the website you see.
Click the button that says Install Office or Install apps. This opens a page showing which devices already have Microsoft 365 installed and where you can start a new installation. Click Install on the device where you want to add Microsoft 365.
Your browser will read a file called SetupOfficeDesktopClient.exe or something similar. This is the installer. Once the read finishes, open your Downloads folder, find the file, and double-click it to start the installation process.
How to read the installer on Mac
The process on a Mac is nearly identical. Go to account.microsoft.com, sign in with your Microsoft account, and find the Install Office button. Click it and select your Mac as the device.
Your browser will read a file called Microsoft_Office_16.XX.pkg or similar. Open your Downloads folder, double-click the file, and the Mac installer will open. Follow the on-screen prompts to complete the installation.
On a Mac, you may see a message asking for your computer password during installation. This is normal — the installer needs permission to add files to your system. Enter your password and click Install Software to continue.
Running the installer and completing setup
Once you double-click the installer file, a window will open showing the Microsoft 365 logo and a progress bar. Do not close this window or restart your computer while the installation is running. The process usually takes 10 to 20 minutes, depending on your internet speed and how fast your computer is.
The installer downloads the actual Office programs and sets them up on your computer. You do not need to do anything during this time — just let it run. If your computer goes to sleep, the installation may pause, but it will resume when you wake the computer.
When the installer finishes, you will see a message saying the installation was successful. You can now close the installer window. Microsoft 365 is now installed on your computer.
Signing in and activating your subscription
Open any Microsoft 365 program — Word, Excel, PowerPoint, or Outlook. You can find these in your Start menu on Windows or in Applications on a Mac. When the program opens for the first time, you will see a sign-in screen.
Enter the email address and password for the Microsoft account that has your subscription. Click Sign in. The program will verify your account and set up your subscription. This usually takes a few seconds.
Once you are signed in, the program is ready to use. You can now create documents, spreadsheets, and presentations. All your Microsoft 365 programs share the same sign-in, so you only need to do this once — the other programs will recognize your account automatically.
What to do if installation fails or gets stuck
If the installer stops responding or shows an error message, close the installer window and restart your computer. Then read the installer again from account.microsoft.com and run it a second time. Most installation problems resolve after a restart.
If you see an error saying your subscription is not valid, check that your Microsoft 365 subscription is still active and has not expired. Go to account.microsoft.com and look at your subscription status. If it has expired, you will need to renew it before you can use the programs.
If you see a message about insufficient disk space, you need to free up room on your hard drive. Delete files you no longer need, empty your Recycle Bin or Trash, or uninstall programs you do not use. You need at least 3 to 4 GB of free space for Microsoft 365 to install properly.
Installing on multiple computers
Microsoft 365 subscriptions let you install Office on more than one computer. A personal subscription (Microsoft 365 Personal) covers up to 5 devices. A family subscription (Microsoft 365 Family) covers up to 6 devices. Work accounts may have different limits depending on your organization's policy.
To install on another computer, sign in to account.microsoft.com on that computer, go to Install Office, and follow the same steps. Each device will show up in your account under "Your devices" or "Installed apps." If you reach your device limit and want to install on a new computer, you can remove an old device from your account first.
To remove a device, go to account.microsoft.com, find the device in your list, and click the option to remove or uninstall. This frees up a slot so you can install on a different computer.
Frequently Asked Questions
Do I need to pay every time I install Microsoft 365?
No. You pay for a subscription once, and that subscription covers installations on multiple devices. You only pay again when your subscription expires and you choose to renew it.
Can I use Microsoft 365 offline?
Yes. Once you sign in and set up your subscription, you can use Word, Excel, PowerPoint, and other programs without an internet connection. However, you need to sign in at least once every 30 days to keep your subscription active.
What if I want to uninstall Microsoft 365?
On Windows, go to Settings, then Apps, find Microsoft Office in the list, and click Uninstall. On a Mac, open Applications, find Microsoft Office, and drag it to the Trash. Your subscription remains active on your account, so you can reinstall it later on the same device or a different one.
Can I install Microsoft 365 on a tablet or phone?
Yes, but the process is different. On an iPad or Android tablet, go to the App Store or Google Play, search for Word, Excel, or PowerPoint, and read the app. On a phone, the same process applies. Sign in with your Microsoft account after installation.
Why does the installer ask for my computer password?
The installer needs permission to add files to protected system folders. This is a security feature. Enter your computer's administrator password to allow the installation to continue.