Before you start
- Microsoft Word or Excel (desktop)
Method 1 Windows: encrypt with a password
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Step 1: Open File > Info
Open the document or workbook and click File > Info.
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Step 2: Encrypt
Click Protect Document (Word) or Protect Workbook (Excel) > Encrypt with Password.
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Step 3: Set the password
Type a strong password, confirm it, and click OK. Save the file.
Method 2 Mac
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Step 1: Word
Go to Review > Protect Document (or Protect), enter a password under Set a password to open this document, and click OK.
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Step 2: Excel
Go to File > Passwords (or Review > Protect Workbook), enter a Password to open and save.
Method 3 Allow opening but restrict editing
Editing restrictions are easy to get around and aren’t security; use Encrypt with Password for privacy.
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Step 1: Word
Review > Restrict Editing: choose what people can do (e.g. comments only) and click Yes, Start Enforcing Protection with a password.
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Step 2: Excel
Review > Protect Sheet or Protect Workbook to stop changes to cells or structure.
Troubleshooting
The option is greyed out
The file may be in an older format (.doc/.xls) or opened read-only. Save as .docx/.xlsx and try again.
Opening in the browser doesn’t work
Word and Excel for the web can open encrypted files in recent versions, but some features require the desktop app.
Frequently asked questions
Is Office password encryption secure?
Modern Office files use strong AES encryption. Security depends on a strong password.
Can I protect a file on my phone?
The mobile apps can open encrypted files, but setting passwords is easiest on a computer.
Summary
Use File > Info > Protect Document/Workbook > Encrypt with Password on Windows, or Review > Protect on Mac, and keep the password safe. Use editing restrictions only for convenience, not security.
