Password Protect an Excel File: so it cannot be opened

A file password encrypts the workbook. Without the password it cannot be opened — not by Excel, not by anything else.

Steps

1. File › Info.
2. Click Protect Workbook › Encrypt with Password.
3. Type the password. OK. Type it again to confirm. OK.
4. Save the file (Ctrl + S). The password only takes effect after saving.

Check it worked

Close the file and open it again. Excel asks for the password before showing anything.

Let people open it but not change it

1. File › Save As › choose a folder.
2. Click Tools (next to Save) › General Options.
3. Type a Password to modify. Leave “Password to open” empty. OK, Save.

Anyone can open it read-only; only people with the password can save changes.

Remove the password

File › Info › Protect Workbook › Encrypt with Password, delete the dots so the box is empty, OK, save.

Important

• There is no recovery. Lose the password, lose the file. Store it in a password manager.
• Use a long password — 12+ characters. Short ones can be cracked.
• Mac: Review › Protect Workbook › tick Password to open.

Only want to stop people editing certain cells? That is lock cells, a different tool.