Excel (Mac) - How to password protect and encrypt a workbook

This document explains how to require a password to open a workbook which also encrypts the file.

To Encrypt an Excel Document with a Password

CAUTION: If you forget your password, the file can not be recovered!

1) With the spreadsheet you want to protect open, click File > Save As. 

Select Save As from the File menu.

2) Give the document a name, as always.

Hint: If you already saved the sheet without encryption, and don't want to leave a plain-text copy on your drive, use the same name.  This overwrites the plain-text version, and generates a warning, which is safe to ignore in this case.

3) Click Options.

The Options dialogue includes encryption.

4) In the Password to open box, type a password, then click OK.

Simple Password Dialogue

5) In the Confirm Password dialog box, type the password again, then click OK.

Confirm password

6) Don't forget to save!  Like any change in a document, password protection is not applied on disk until you save.