How to Password Protect a PDF File — Free & Secure

Sending a contract, bank statement, medical report, or any private document as an unprotected PDF is a risk most people take without thinking. Anyone who receives the file can open it, read it, copy from it, and forward it to anyone else. Adding a password to a PDF takes less than a minute and prevents all of this.

What Does Password Protecting a PDF Mean?

Password protecting a PDF means encrypting the file so anyone who tries to open it must enter a password first. The protection is built into the file itself — it travels with the document wherever it goes.

PDF password protection uses AES encryption — the same standard used by banks and government agencies to protect sensitive data.

How to Password Protect a PDF on Mac

1. 1Open the PDF in Preview
2. 2Go to File, then Export as PDF
3. 3Check the box labelled Encrypt
4. 4Enter and verify your password
5. 5Click Save

How to Password Protect a PDF on Windows

Using Microsoft Word

1. 1Go to File, then Save As
2. 2Choose PDF as the format
3. 3Click Options
4. 4Check Encrypt the document with a password
5. 5Enter your password and save

Using LibreOffice (Free)

1. 1Open your document in LibreOffice
2. 2Go to File, then Export as PDF
3. 3In the Security tab, enter an open password
4. 4Click Export

How to Password Protect a PDF on iPhone and iPad

Browser-based tools in Safari work without installing any application. Look for a tool that specifies AES-256 encryption and immediate file deletion after processing.

Before protecting, use our Compress PDF tool to prepare your file.

How to Choose a Strong PDF Password

• Use at least 12 characters
• Mix uppercase letters, lowercase letters, numbers, and symbols
• Avoid any word that appears in a dictionary
• Avoid personal information like names or birthdays
• Use a different password for each protected document

How to Share a PDF Password Safely

Never send the password in the same message as the protected PDF. Use a different channel: phone call, text message, Signal, or a password manager sharing feature.

PDF Open Password vs Permissions Password

Open password — prevents anyone from opening the PDF without the password.

Permissions password — does not prevent opening the PDF, but restricts what the recipient can do: printing, copying text, editing, or extracting pages.

How to Remove a PDF Password

On Mac: Open the encrypted PDF in Preview, enter the password, go to File then Export as PDF, and leave the Encrypt checkbox unchecked.

In LibreOffice: Open the PDF, go to File then Export as PDF, open the Security tab, and clear the password fields.

Before Password Protecting a Large PDF

Compress it first using our Compress PDF tool. If you need to combine several documents into one protected PDF, use our Merge PDF tool first.

Frequently Asked Questions

Is it free to add a password to a PDF?

Yes. Preview on Mac, LibreOffice on Windows, and browser-based tools on all devices add AES encryption at no cost.

Can a password-protected PDF be cracked?

A PDF protected with AES-256 encryption and a strong password is extremely difficult to crack.

What happens if I forget my PDF password?

There is no official way to recover a forgotten PDF password. Always keep a secure record of passwords in a password manager.

Does password protecting a PDF change the file size?

Applying password protection increases the file size slightly — typically less than one percent.