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How to lock cells in Excel, and why it seems not to work

The reason how to lock cells in excel gets searched so often is not that the steps are hard. It is that people follow them, tick the box, go back to the sheet — and the cells are still editable. Nothing has gone wrong. The feature simply does not work the way its name suggests, and Microsoft says so in a note that almost nobody quotes.

“If you try these steps on a workbook or worksheet you haven’t protected, you’ll see the cells are already locked. This means that the cells are ready to be locked when you protect the workbook or worksheet.”

Microsoft’s own note, read 22 August 2026, and it explains the complaint everybody has. Every cell in a new spreadsheet is already marked Locked. Ticking that box changes nothing on its own, and the cells stay editable — because the setting does not take effect until the sheet is protected.

Which means the job is the other way round

You are not locking cells. You are unlocking the few that should stay editable, and then switching protection on. Microsoft says as much: “It’s a best practice to unlock any cells that you may want to change before you protect a worksheet.”

Select the cells people should be able to type in The input boxes, the blank column, the cells your colleague is meant to fill. Not the ones you want to protect.
Open Format Cells “On the Home tab, in the Alignment group, select the Alignment Settings arrow to open the Format Cells popup window.”
On the Protection tab, clear the Locked box You are removing the default from the cells that should remain editable.
Review tab → Protect group → Protect Sheet This is the step that makes any of it real. Everything still marked Locked becomes read-only; everything you cleared stays editable.

Doing it in the other order — ticking Locked on a few cells and then wondering why nothing changed — is the single most common way this goes wrong, and it happens because the checkbox describes an intention rather than a state.

A quick way to check what you have done. After protecting the sheet, click a cell you meant to lock and try to type. Excel should refuse with a message. Then click one you meant to leave open and type something. If both behave as you expected, you are finished; if neither does, you have almost certainly protected the sheet without clearing the Locked box on the input cells, and everything is read-only.

Protect Sheet and Protect Workbook are different things. Protecting a sheet controls what can be edited inside it. Protecting a workbook controls its structure — whether sheets can be added, deleted, renamed or hidden. People reaching for one when they wanted the other is common, and the two sit next to each other in the same group on the Review tab.

What this protects against, and what it does not

Microsoft describes removing protection in one short sentence: “To remove protection, simply remove the password.” And the feature sits under a heading about restricting changes rather than about security.

That framing is the right one to carry. Sheet protection is designed to stop accidents — a formula overwritten by somebody filling in a form, a header row typed over, a column deleted by mistake. It is very good at that, and it is what the feature is for.

It is not a way to keep information from somebody determined to read or change it, and it is not encryption. If a spreadsheet contains something that genuinely must not be seen or altered by the people who can open the file, protection is the wrong tool and the answer is not to send them the file. That last sentence is our judgement rather than Microsoft’s wording.

The password is worth thinking about before you set one. Protection can be applied without a password at all, which still prevents accidental edits and lets anybody who needs to make a real change simply turn it off. That is often the better arrangement for a shared internal file — it signals intent without creating a thing that can be lost. If you do set a password, the ordinary rule applies: a password you cannot recover is a file you cannot edit.

What to lock in practice. The cells worth protecting are almost always the same three kinds: formulas, which break silently when overwritten; headers, which everything else depends on; and reference data that other cells look up. Everything else can usually stay open, and a sheet where only those three are protected is far more pleasant to use than one where everything is locked because it was easier.

The steps, the note about cells already being locked, and the best-practice tip are quoted from Microsoft’s own Excel documentation, read on 22 August 2026. The check afterwards, the advice on what to lock, and the point about what protection is not are ours, and are marked as such.

Where to start

Four ways in.

“I ticked Locked and nothing changed.”: That is the note above — see protecting properly
“I want colleagues to fill in some cells only.”: Unlock those, protect the rest — protecting properly
“I want to stop people seeing something.”: Wrong tool — go to when it really matters
“Somebody broke my formulas.”: See the spreadsheet itself

Protecting properly

The order matters more than the settings, and the check afterwards takes ten seconds.

Freezing rows in ExcelOne rule from Microsoft explains every case, including the two that send people to forums.Open this floor → Sorting alphabeticallyOne word in Microsoft’s first step keeps your rows together.Open this floor → Merging cells in ExcelMicrosoft says merging deletes the other cells, and merged blocks break sorting.Open this floor →

When it really matters

Protection stops accidents. Keeping information from somebody who has the file is a different problem with different answers.

PasswordsThe tower on making one breach stop at one account.Open this floor →

Customer data and the lawWhat you are holding about your customers, and what that obliges you to do.Being built

What happens to your textWhat each service says it keeps, quoted with the date.Being built

The spreadsheet itself

Most broken formulas are a structural problem rather than a malicious one, and protection is only half the fix.

Removing duplicates in ExcelThree tools and only one deletes, and what Excel actually counts as a duplicate.Open this floor →

Spreadsheets as softwareThe point at which a spreadsheet has quietly become an application.Being built

BackupsThe arrangement that makes an irreversible change survivable.Being built

A protected sheet still travels as a file. What happens to it afterwards is a separate question.

Large files by emailSending something too big to attach, without uploading it somewhere you have not read the terms of.Open this floor → Safe PDF convertersWhat an upload site keeps, and when it matters.Open this floor → How long to keep recordsThe periods two tax authorities publish, before you delete anything.Open this floor →

What this tower will not do

It will not describe sheet protection as security. Microsoft frames it as restricting changes, and that is what it is good at.

It will not give the steps in the order that fails. The cells are already locked; the work is unlocking the ones that should not be.

And it will not recommend a password by default. Protection without one prevents accidents and cannot lock you out of your own file. What holds instead is simple: the steps, the note that cells are already locked, and the best-practice tip are quoted from Microsoft’s own Excel documentation, with the date it was read.

Where this page got its facts

Microsoft Support — Lock cells to protect them in Excel, including the note that cells are already locked before a sheet is protected and the advice to unlock editable cells first — support.microsoft.com, read 22 August 2026.

Written by Alberto Gulotta

Founder and editor of AI Tools Primer, writing from Palermo, Italy. Thirty-five years of taking computers apart, starting with a Commodore 64 — the long version is on the about page.

Something wrong on this page? Write to aitoolsprimer@gmail.com and it gets fixed.

Written on 22 August 2026.

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