The Best Scientific Calculator Chrome Extensions in 2026, and the Permissions the Store Never Shows You

Every "best Chrome calculator" list ranks the same way: user count, star rating, a screenshot. None of them tell you the one thing that actually matters for something you install into your browser, which is what the extension is allowed to touch. That is not laziness on their part. The Chrome Web Store does not publish permissions on a listing page at all, not even on its Privacy tab. So we read the packaged manifest.json of all thirteen instead.

The short answer

For most people: Scientific Calculator by raad.dev. It has 100,000 users, 4.3 stars from 95 ratings, it is open source, it was updated in April 2026, and its manifest requests only contextMenus and system.display. It asks for access to no website whatsoever. It also carries both of the store's quality badges. Nothing else in this set combines that scale with that restraint.

If you want a side panel rather than a popup: Sidebar Calc requests exactly one permission, sidePanel, and nothing else.

If you need matrices, vectors or complex numbers: nothing in the popular tier does them. That is a genuine gap in this market rather than a sales line, and it is the reason our own extension exists. You can also just use a browser-based scientific calculator with no install at all, which is what the last section is about.

The one to avoid: Floating Scientific Calculator. Details in the red flags section, and they are not a matter of taste.

How we checked

This matters, because the numbers below are only worth reading if you know where they came from.

• Listing data (rating, user count, version, last updated, size, developer, privacy policy link) was read directly off each Chrome Web Store listing page on 6 September 2026.
• Permissions are not on the listing page, so they came from the packaged manifest.json mirrored by chrome-stats.com, cross checked against crxsoso.com. Both agreed on all thirteen. For the two open source extensions the mirrored manifest matched the GitHub source exactly.
• Developer links and privacy policies were fetched with curl following redirects, and DNS was checked against 1.1.1.1.
• We did not download or run any extension package. That means we cannot tell you whether any of these wraps someone else's calculator in an iframe, and we have not claimed it.

Where the store does not display a field, the table says "not shown" rather than a guess.

All thirteen compared, plus ours

Sorted by user count. "Host access" is the important column: it is what the extension can reach on the pages you browse.

All thirteen are Manifest V3. None declares optional permissions. The two headline numbers to sit with: the most popular extension in the category asks for nothing, and the third most popular asks for everything.

The permission red flags

Access to every website you visit, plus your cookies

Floating Scientific Calculator, 10,000 users, 4.7 stars, carrying a Featured badge. Its manifest declares "host_permissions": ["*://*/*"], the cookies permission, and a content script matching <all_urls> injected at document_start in all frames.

Read plainly, that is read and write access to every site you open and to the cookies on those sites. Cookies are session tokens. No calculator feature requires them. A floating window over the page needs a content script, which is a fair reason to be on the page, but it does not need cookies and it does not need write access to every origin.

Two facts compound it, both checked on 6 September 2026. The developer website printed on the listing, floatingcalc.com, does not resolve: DNS returns NXDOMAIN. And the extension was last updated 21 February 2024, which is more than two and a half years ago. An extension holding permissions over every website, with a dead developer domain and no security updates for that long, is the exact profile worth removing.

We are describing what the manifest declares and what DNS returns. We are not alleging that anything has been done with that access.

A clean permission list that understates the reach

Advanced Calculator, 8,000 users, declares only "permissions": ["storage"]. That looks like restraint. But its content script matches http://*/* and https://*/*, so its code runs inside every page you load, and that grant does not appear in the permissions array at all.

This one is worth explaining rather than condemning. It is a floating calculator that sits on the page, so it needs to be on the page, the developer replies to reviews, and it shipped an update on 3 September 2026. The lesson is about reading manifests: a short permissions array does not mean limited access, because content script matches are granted separately.

Tab access a calculator does not need

Scientific Calculator by ran198, 179 users, declares "permissions": ["storage", "contextMenus", "system.display", "tabs"]. The tabs permission exposes the URL, title and favicon of every open tab. Nothing in a calculator needs that. The same listing calls itself "Google Scientific Calculator" in its tagline and "Scientific Calculator Pro" throughout its description, and its privacy policy is a Notion page rather than a document on a domain the developer owns.

An empty permission list and a hijacked new tab

Calculator Extension, 2,000 users, 2.1 stars, declares "permissions": []. Genuinely empty. It nevertheless sets "chrome_url_overrides": {"newtab": "./src/main.html"}, replacing your new tab page, and its own listing states that it "includes a search function that uses the Microsoft Bing search engine". Redirecting a new tab page into a chosen search engine is a monetisation pattern, and no permission string discloses it. Its developer domain, mysimplecalculator.com, fails DNS, so its privacy policy cannot be read. Five of its seven reviews say it does not work.

Abandoned, broken and unreachable

Separate from permissions, a good deal of this category is simply not maintained.

• Free Scientific Calculator, 2,000 users, 4.1 stars, Featured. Last updated 24 October 2022. Its privacy policy points at charactercounttool.io, an unrelated website. Four separate reviews report that division and basic arithmetic return wrong answers.
• Scientific Calculator by yoosfuhl, 463 users, version literally "1", last touched September 2022.
• Scientific Calculator Free, 24 users, has 8 five star reviews all posted inside a 48 hour window, one from a reviewer sharing the developer's surname. Read that pattern for what it is.

Note how little a Featured badge tells you. Two of the three above carry one, Free Scientific Calculator and the yoosfuhl listing, and so does Floating Scientific Calculator from the previous section.

How to check any extension yourself

Four steps, none of which need any tooling.

1. Read the manifest before you install. The item id is the long string in the listing URL. Paste it into a mirror such as chrome-stats.com and open the manifest. Look at permissions, host_permissions and, critically, content_scripts.matches. Every id we used is in the list at the end.
2. Check the last updated date on the listing. Anything holding host permissions and older than about a year deserves suspicion.
3. Click the developer website and the privacy policy. If either fails to load, or the policy lives on an unrelated domain, a Notion page or a Google Doc, that tells you how seriously the project is run.
4. Read the one and two star reviews first, and check whether the five star ones are clustered in a few days.

And test the arithmetic. Type 0.1+0.2, and in degree mode type sin(180). A calculator that answers 0.30000000000000004 and 1.2246e-16 is exposing raw floating point rather than handling it. We wrote a fuller version of that test battery in our guide to what makes a calculator truly scientific.

Our own extension, honestly

WideMath Scientific Calculator, item id fcajfilajkffipdjeafhnggdjniofjie. We are not going to call it the best, because 102 users cannot support that claim.

What is genuinely good. It declares one permission, sidePanel, with no host permissions and no content scripts, which is the joint cleanest in this set alongside Sidebar Calc. It cannot read the pages you visit. It is the only extension here with matrix, vector and complex number modes. It is 275KiB against 5.36MiB for Floating Scientific Calculator, it was updated on 18 August 2026, and it declares Trader status with a real postal address, which nine of the thirteen competitors do not.

What is weak, and you should weigh it.

• Our six reviews are clustered and connected to us. All six are dated 13 to 17 August 2026, and several of the names are the developer's own name or share his surname. That is the same pattern we flagged on Scientific Calculator Free above, and it would be dishonest to run that criticism and hide this. Treat our 5.0 as unproven, not as evidence.
• Four of those six reviews describe the website rather than the extension, which weakens them further.
• 102 users, against 100,000 for the leader. No Featured badge and no store badges at all.
• English only. So are six of the thirteen competitors here, including both of the largest, so this is a smaller disadvantage than it sounds. The other seven ship 5 to 54 languages and get store surface in non-English locales that we do not.
• It does not currently appear in the Chrome Web Store's own search results for "scientific calculator", so today it is discoverable by name only.

The narrow claim we will stand behind: it asks for one permission, cannot read any page you visit, is the only extension in this comparison with matrix, vector and complex number modes, and was updated last month. Every clause there is checkable from the listing and the manifest.

When you do not need an extension at all

This is worth saying even though it costs us installs. For most people a browser page is the better answer.

A web page cannot read your other tabs, cannot touch your cookies and cannot run on other sites, because the browser's origin model forbids it. That is a stronger guarantee than any permission list, and you get it without auditing anything. Install a calculator page to your home screen or desktop and it works offline too.

An extension earns its keep in exactly one case: you want the calculator pinned in a side panel or floating over the page you are reading, always a keystroke away. If that is not you, open a scientific calculator in a tab and skip this entire risk category.

Frequently asked questions

Every extension, with its item id

So that nothing here has to be taken on trust. Each id links to its Chrome Web Store listing. Listing data was read on 6 September 2026 and will drift; permissions came from the packaged manifest mirrored by chrome-stats.com, cross checked against crxsoso.com.