How to Password-Protect a PDF

Passwords & SecurityUpdated Sep 23, 2026
Quick answer

On Mac, open the PDF in Preview and choose File > Export, tick Encrypt and set a password. On Windows, use Word (File > Save As > PDF > Options > 'Encrypt the document with a password') or LibreOffice's PDF export. Online tools also add passwords. Use a long password and share it separately from the file.

Mac (Preview, built-in)

  1. Open the PDF in Preview.
  2. File > Export…
  3. Tick Encrypt, then enter and verify a password.
  4. Optional: Permissions… to restrict printing, copying or editing.
  5. Save.

Windows (Microsoft Word)

If the document is a Word file, or you open the PDF in Word:

  1. File > Save As > type PDF.
  2. Click Options… > tick Encrypt the document with a password.
  3. Enter the password and save.

Windows (LibreOffice, free)

File > Export as PDF > Security tab > Set passwords… Set an open password and optionally a permissions password.

Adobe Acrobat Pro

Tools > Protect > Encrypt with Password. Choose the compatibility level Acrobat X and later for AES-256.

Online tools

Many online “protect PDF” tools add AES encryption. Remember that the file (and password) pass through their server.

Password best practices

  • Use 12+ characters, or a passphrase of 4–5 random words.
  • Send the password through a different channel (text or phone vs email).
  • Store it in a password manager. A lost password means a lost document.

Frequently asked questions

How secure is a password-protected PDF?

With AES-256 encryption and a long random password, very secure. With a short password like a birth date, it can be guessed by software in hours or less.

Can I stop people from printing or copying my PDF?

You can set a permissions password, but it's easily bypassed and anyone can take screenshots. It discourages casual copying but isn't real protection.

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