The fastest way: password-protect the file

Open your Excel file, then go to File > Save As. In the dialog box, click Tools (or More options on Mac), then select General Options. You'll see a field labeled "Password to modify". Type a password there — anyone who opens the file will see it, but they won't be able to make changes without entering that password.

When you click Save, Excel will ask you to re-enter the password to confirm it. After that, the file is protected. People can open it and read it, but they'll get a prompt asking for the password if they try to edit anything. If they don't know the password, they can only view the file in read-only mode.

This method works in Excel on Windows and Mac, and in Google Sheets as well. It's the simplest approach if you just want to prevent accidental changes or keep people from editing without permission.

Key Takeaways

  • The password-protect method (File > Save As > Tools > General Options) is the fastest way and works across Windows, Mac, and Google Sheets.
  • You can set a password to modify the file so people can view it but cannot save changes without the password.
  • File properties in Windows let you mark a file read-only, but this only prevents changes if someone doesn't remove the attribute themselves.
  • Sharing settings in Google Sheets and OneDrive let you restrict editing permissions by person, which is stronger than a password if you're working with a team.
  • Excel's "Protect Sheet" and "Protect Workbook" features lock specific cells or sheets, not the entire file, and are meant for preventing accidental changes within a document you're actively using.

Using file properties to mark the file read-only (Windows)

Right-click the Excel file on your computer, then select Properties. At the bottom of the General tab, you'll see a checkbox labeled Read-only. Check that box and click Apply.

This method has a catch: it only prevents changes if the person opening the file doesn't uncheck the read-only attribute themselves. It's a speed bump, not a lock. Someone determined to edit the file can remove the read-only flag and make changes. Use this if you want to prevent accidental edits from people who aren't trying to work around it, but don't rely on it for security.

This approach doesn't work on Mac — macOS doesn't have the same read-only file attribute. If you're sharing files across Windows and Mac computers, password protection is more reliable.

Protecting specific sheets or cells within the file

If you want people to be able to edit some parts of your spreadsheet but not others, use Protect Sheet instead. Go to Review > Protect Sheet, set a password if you want one, and choose which actions people are allowed to do (like select cells or sort data, but not insert rows or change formulas).

You can also protect the entire workbook structure — go to Review > Protect Workbook — so people can't add, delete, or rename sheets. This is useful if you have a template with multiple sheets and you want to lock the structure but let people fill in data on certain sheets.

These features are meant for spreadsheets you're actively using with a team, where you want to guide people toward the cells they should edit. They're not meant to make a file completely read-only — they're more like guardrails.

Sharing restrictions in Google Sheets and OneDrive

If your file lives in Google Sheets or OneDrive, you can control who can edit it through sharing settings instead of passwords. In Google Sheets, click Share, then change the permission from "Editor" to Viewer for the people you want to restrict. They'll be able to see the file but not make any changes.

In OneDrive or SharePoint, right-click the file, select Share, and set permissions to Can view instead of Can edit. This approach is stronger than a password because it's tied to the person's account — they can't bypass it by entering a code.

The downside is that this only works if the file is stored in the cloud. If someone downloads a copy to their computer, the sharing restrictions don't follow it. For that reason, password protection is still the better choice if you're emailing files or sharing them outside your organization.

What happens when someone tries to edit a read-only file

If you've password-protected the file and someone tries to edit it, Excel will show a dialog asking for the password to modify. If they don't have it, they can click Read-Only to open the file in view-only mode. They can read everything, copy data, and print, but they can't save any changes to the original file.

If they want to make changes, they have to save a copy with a new name — the original stays untouched. This is actually useful: it means people can experiment with the data without risking the original, and you know the source file hasn't been altered.

Removing read-only protection if you forget the password

If you set a password to modify and then forget it, you're locked out of editing your own file. Excel doesn't have a built-in password recovery tool. You'll need to use a third-party password recovery tool, which can be expensive and isn't always reliable.

The best prevention is to write down the password somewhere secure — a password manager is ideal. If you're protecting a file you plan to edit regularly, make sure you'll remember the password or have it stored somewhere you can find it.

Frequently Asked Questions

Can I make a file read-only without a password?

Yes. On Windows, right-click the file, select Properties, and check the Read-only box. On Mac, right-click, select Get Info, and check "Locked". On Google Sheets or OneDrive, use sharing settings to restrict permissions. These methods don't require a password, but they're easier to bypass than password protection.

If I password-protect a file, can people still copy data out of it?

Yes. Password protection prevents saving changes to the file, but people can still open it, read it, select cells, and copy data to paste elsewhere. If you need to prevent people from seeing the data at all, you need file-level encryption or access controls, not just read-only protection.

Does read-only protection work if someone emails me the file?

Password protection travels with the file — it works whether the file is emailed, shared on a drive, or downloaded. File properties (Windows read-only attribute) don't travel as reliably, especially across different operating systems or if the file is uploaded to the cloud.

What's the difference between "Protect Sheet" and making the whole file read-only?

Protect Sheet locks specific cells or actions within a sheet you're actively using — people can still edit other cells and save the file. Making the file read-only prevents any changes from being saved at all. Use Protect Sheet for templates where you want to guide editing; use file-level read-only for files you don't want changed.

Can I make a file read-only for some people but not others?

Yes, but only with cloud-based sharing (Google Sheets, OneDrive, SharePoint). You can give some people Editor access and others Viewer access. With password protection on a file you email or download, everyone either has the password or doesn't — you can't restrict it by person.