In Excel: go to File ▸ Info ▸ Protect Workbook ▸ Encrypt with Password, set a password, and the whole .xlsx then requires it to open.
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. Keep the inputs visible and clearly labelled and the whole thing stays auditable — anyone who opens the file later, including you, can see at a glance exactly what feeds the result and change one assumption without hunting through the formula. The difference between a quick fix and a sheet you can trust is the extra minute you spend validating “remove excel encryption”. Start on a copy or a tiny sample, keep the affected cells visible, and compare the result with the tool above before you touch the real workbook. 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. The point is a data step that keeps your analysis trustworthy, but the practical win is that someone else can open the file and understand what happened without asking you.
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 there is any chance you will reuse this, drop it into a small template tab right now: a labelled input area on the left and the formula beside it, checked once against the tool above. Next time the same question comes up, the answer is a single paste away instead of a rebuild from memory.
In Google Sheets
Everything above works in Google Sheets too. Excel and Sheets share the formula syntax used here; only the surrounding menus are arranged differently. That portability is deliberate — learn it once and it follows you between the two tools and across Windows and Mac. Keep this page bookmarked for the next time the same question comes up. Better still, rebuild the example once in your own sheet — doing it yourself, with the tool above to check against, is what turns a copied formula into a technique you own. Treat “remove excel encryption” as a small building block rather than a chore. Once the inputs sit in their own cells and the formula reads from them, the same setup answers a dozen related questions with a tweak, and Excel keeps every dependent figure current as the data changes. The tool above is there so you can rehearse and verify before committing anything to a real workbook; the steps and worked example are there so the logic sticks. Get it right once and it stops costing you time — it starts saving it, every time the question comes back around.
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.