How to password protect a PDF
Sending a contract, an ID copy or a bank statement by email or chat is risky if anyone can open it. A password fixes that in a minute.
This guide shows the quickest free ways to lock a PDF on a phone, Windows PC or Mac, plus how to choose a password that is actually safe.
Password protect a PDF in your browser
- Open the Protect PDF tool.
- Add your PDF.
- Type a password and type it again to confirm.
- Press Protect PDF and download the locked copy.
The file is encrypted with AES-256 inside your browser, so neither the PDF nor the password is uploaded. It works the same on a phone, tablet and computer, and your original file stays unchanged.
If your PDF starts as a Word file
In Word, choose File > Save As, pick PDF, click Options and tick Encrypt the document with a password. Enter the password and save. The PDF is locked from the start, with no extra tool.
On a Mac
Open the PDF in Preview, choose File > Export, tick Encrypt, enter a password and save the new file. Keep the original unlocked copy somewhere private, or delete it once you have checked the locked one opens.
How to choose a good password
- Use 12 characters or more. Length matters more than tricks.
- Avoid names, birthdays, phone numbers and words like password or 12345.
- Three or four unrelated words joined together are easy to remember and hard to guess.
- Use only English letters, numbers and symbols, so every PDF reader can open the file.
- Store it in a password manager so you can find it later.
Send the password separately
If you email the locked PDF and put the password in the same email, the lock does nothing. Send the file by email and the password by a different route, such as a text message or a phone call.
What a PDF password does and does not do
- It stops people without the password from opening the file.
- It does not hide that the file exists or who you sent it to.
- Once someone has the password and opens the file, they can still copy, print or share it.
- A forgotten password cannot be recovered, so keep a safe copy of it.
Check that it worked
Open the locked PDF in a different app or browser tab. It should ask for the password before showing anything. If it opens straight away, the protection did not apply, so run the tool again on the original file.
Combine with other steps
Remove pages you should not share first with Remove pages, or add a CONFIDENTIAL stamp with Watermark PDF, then lock the final version. Compress large files before locking, because a locked file cannot be edited.