In Excel: go to File ▸ Info ▸ Protect Workbook ▸ Encrypt with Password, set a password, and the whole .xlsx then requires it to open.
On this page7
Open File ▸ Info, click Protect Workbook, and choose Encrypt with Password.
Type a strong password, click OK, then re-enter it to confirm.
Save the file (Ctrl+S) so the encryption is written to disk.
Test it by closing and reopening the workbook — it should prompt for the password before opening.
What this does
Encrypting a workbook with a password locks the entire file so it cannot even be opened without the password — the contents are scrambled on disk, not merely set to read-only. This is workbook-level (file-level) encryption, reached through File ▸ Info ▸ Protect Workbook ▸ Encrypt with Password, and it is completely separate from sheet protection: it controls who can open the file at all, rather than which cells can be edited once it is open. The same idea underpins a lot of everyday Excel work, so the few minutes spent getting it right here pay back across every sheet you build afterwards. Treat it as a pattern, not a one-off, and it stops being something you look up and starts being something you reach for. For “unencrypt excel file”, the reliable version is a short checking loop, not just the first command that appears to work. Run it on a deliberately small range first, watch how the affected cells change, and only then apply the same setup to the full sheet. When this is a ribbon command, the selection matters more than the button: confirm the range, apply the command, then spot-check the output before saving. That is what makes a data step that keeps your analysis trustworthy useful in real work: repeatable, auditable, and not dependent on memory or luck.
A worked example
You have a payroll workbook to email. Open File ▸ Info ▸ Protect Workbook ▸ Encrypt with Password, type a password such as Spr1ng!2026, confirm it, and save. The next time anyone — including you — double-clicks the .xlsx, Excel demands that password before it will display a single cell. Without it the file is unreadable; lose the password and there is no built-in way back in. Encrypt a workbook when the whole document is sensitive — salaries, contracts, personal data — and must not be readable by anyone who gets the file. It is the right tool when the goal is "nobody opens this without the password", as opposed to merely keeping a few formula cells from being overwritten. If this is something you do often, add the command to the Quick Access Toolbar (right-click it on the ribbon and choose Add to Quick Access Toolbar) or learn its shortcut, so next time it is one click instead of a hunt through the menus.
In Google Sheets
This is a command rather than a formula, so there is no syntax to carry over. Google Sheets arranges its commands in menus across the top instead of a ribbon, names some of them differently and does not have every Excel command — look for the equivalent in the Sheets menus or its help before assuming the steps match. Keep this page bookmarked for the next time the same question comes up. Better still, repeat the steps once in your own workbook — doing it yourself is what turns a copied answer into something you remember. Here is the takeaway for “unencrypt excel file”: follow the steps at the top, check the result on the sheet itself, and keep undo in mind while you experiment. Done once deliberately, it becomes something you do from memory in Excel rather than something you search for again.
Common mistakes
- Confusing this with Protect Sheet — encryption controls opening the file, not which cells can be edited.
- Losing the password: encrypted workbooks have no official recovery, so a forgotten password can mean permanent lockout.
- Assuming a read-only or "mark as final" setting is encryption — only Encrypt with Password actually scrambles the file.
- Relying on it for a shared OneDrive file where co-authoring expects an unencrypted document; encryption can block online editing.
Frequently asked questions
Is encrypting the file the same as protecting a sheet?
No. Encryption stops the file from opening without a password; sheet protection (Review ▸ Protect Sheet) lets the file open but locks certain cells from editing.
Can I remove the password later?
Yes — open the file with the password, return to File ▸ Info ▸ Protect Workbook ▸ Encrypt with Password, clear the password box, and save.
What if I forget the password?
There is no official Microsoft bypass for a forgotten open-password; the encryption is genuine, so always store it somewhere safe before you rely on it.