A spreadsheet often holds the things you least want exposed or broken — salary data, customer lists, the formulas a whole report depends on. Protecting it isn’t one switch; it’s layers: who can open the file, who can edit it, and what specifically they can change. Excel and Google Sheets each offer these layers, but in different ways, and the most important one isn’t a password at all. This covers both platforms, from controlling access down to locking individual cells, plus the security habits that matter more than any single feature.
The first line: control who has access
Before any cell-level locking, the biggest security decision is who can reach the file at all — and at what level. This single control prevents more problems than everything else combined.
| Access level | What they can do |
|---|---|
| View | Read only — no edits; can be restricted from copying or downloading |
| Comment | Read and leave comments, but not change the data |
| Edit | Change anything that isn’t separately protected |
In Google Sheets, the Share button lets you grant each person view, comment, or edit access, and restrict the file to named people instead of “anyone with the link.” In Excel, access is governed by where the file lives — OneDrive/SharePoint sharing, or who can reach the network folder. Get this right and most threats vanish: someone who can only view can’t break a formula or leak edit rights. Default to the least access each person actually needs — view for stakeholders, edit only for contributors — which is also the foundation of collaborating without chaos. Two settings are worth turning on for sensitive view-only files: disable “Editors can change permissions and share” so a viewer can’t quietly re-share the file, and disable downloading/copying/printing for viewers so the data can’t walk out as easily. Neither is bulletproof — a determined viewer can screenshot — but together they raise the bar from “anyone can grab everything” to “casual leaking is blocked.”
Lock cells and protect the sheet in Excel
Excel’s cell protection has a quirk that confuses everyone: every cell is “locked” by default, but the lock does nothing until you protect the sheet. The real workflow is the reverse of what people expect.
- Select the cells people should edit, open Format Cells (Ctrl+1) → Protection, and uncheck Locked.
- Go to Review → Protect Sheet.
- Now the locked cells (everything you left alone — formulas, headers) are read-only, while your unlocked input cells stay editable.
So you don’t lock the cells you want to protect — they’re already locked; you unlock the few you want open, then protect the sheet to enforce it. This is exactly how a shared template should work: people fill in the input cells and physically can’t touch the formulas. You can add a password to the protection, but even without one it stops accidental edits, which is the most common cause of broken shared sheets. Be clear-eyed about what that password is, though: sheet-protection passwords (as opposed to file encryption) are notoriously weak and easily stripped by anyone determined, so treat them as a “keep honest people honest” guardrail, not real security. The genuine protection against a malicious actor is access control — not letting them open the file in the first place — while sheet protection is about preventing well-meaning collaborators from breaking your formulas by accident.
Protect ranges in Google Sheets
Google Sheets does the same job through Protected ranges, with finer control over who’s exempt.
- Select the cells or sheet to lock, then Data → Protect sheets and ranges.
- Choose “Restrict who can edit” and pick who’s allowed — only you, your domain, or named people.
- Or set it to “Show a warning” for a softer guardrail that warns before an edit but allows it.
The warning option is underrated: it lets trusted collaborators edit a protected range after confirming a prompt, which catches accidental edits without locking people out entirely. Google’s guide to protecting sheets and ranges covers the permission choices. This is the Sheets equivalent of locking formulas while leaving input cells open — the same principle behind the protection layer of collaboration tools.
Lock the file itself with a password
Range and sheet protection stop edits, but they don’t stop someone from opening the file. For that, Excel can encrypt the whole workbook.
Encryption is the right tool for a workbook leaving your control — emailed to a client, stored on a shared drive — where sharing permissions don’t reach. For a file that stays in Google Drive or OneDrive, the access controls already cover you, and a file password just adds a thing to lose. Match the tool to where the file actually travels.
Protect the formulas and structure
Beyond who can edit, you can protect the integrity of the sheet — keeping formulas intact and inputs clean.
In Excel, combining Locked with the Hidden attribute (in Format Cells → Protection) hides a formula from the formula bar once the sheet is protected, so people see results without your logic. On both platforms, data validation protects integrity from the other side — it stops bad values entering the cells people can edit. Together, protection (nobody breaks the formulas) and validation (nobody enters garbage) keep a sheet trustworthy as it’s used. Integrity is a kind of security too: a formula silently overwritten does as much damage as data leaked.
The habits that matter most
- ✓ Grant the least access each person needs, and revoke it when the project ends
- ✓ Send passwords out-of-band — never in the same email as the file
- ✓ Don’t store true secrets (passwords, full card numbers) in a spreadsheet at all
- ✓ Lean on version history as your recovery net if data is changed or deleted
Features protect a spreadsheet; habits protect your data. The biggest real-world risks aren’t crackers breaking encryption — they’re a share link left open after a project ends, a sensitive file emailed to the wrong person, or edit access handed out when view would have done. Review who has access periodically, close the door when an engagement wraps, and keep genuinely sensitive secrets out of spreadsheets entirely. Combine sensible sharing, the right locking for your platform, protected formulas, and these habits, and your spreadsheet data stays both safe and intact — which, for most people, is exactly the balance they need.