Most “online scientific calculator” results are the same four-function-plus-trig widget wearing a different skin. The short answer: WideMath’s Scientific Calculator is the only free option here that covers all eight Casio fx-991ES PLUS calculation modes, including calculus, matrices, complex numbers, and base-N, in a single browser tab. That’s why it’s our top pick. Below is how it stacks up against six other calculators people actually search for.
Top picks at a glance
| Tool | Best for | Calculus | Matrices / Complex | Base-N | Offline (PWA) |
|---|---|---|---|---|---|
| WideMath Scientific Calculator | Best overall: full Casio fx-991ES PLUS replica | Yes | Yes | Yes | Yes |
| Desmos Scientific | Pairing with a graphing calculator | No | No | No | No |
| Google Calculator | Quick everyday math from the search bar | No | No | No | No |
| GeoGebra Classic | Geometry and visual algebra | Yes (CAS) | Partial | No | Partial |
| Symbolab | Step-by-step homework help | Yes | Partial | No | No |
| Wolfram Alpha | Verifying answers, deep computation | Yes | Yes | Limited | No |
| Microsoft Math Solver | Scanning handwritten problems | Yes | No | No | No |
Several of these tools are genuinely good at what they do. None of the other six try to be a full scientific calculator, though. They’re graphing tools, query engines, or homework helpers that happen to handle some scientific math on the side.
How we evaluated
We used the calculation modes a physical Casio fx-991ES PLUS covers as the checklist: basic computation, complex numbers (CMPLX), statistics with regression (STAT), base-N binary/octal/hex (BASE), matrices (MAT), vectors (VCT), equation solving (EQN), a table generator, and calculus (definite integration, differentiation, and summation). For each tool, we checked whether that mode exists at all, and if it does, whether it’s free or gated behind a paid tier. That’s a narrower bar than “can this tool do math.” Plenty of calculators handle trig and logs just fine. It’s a bar most of them don’t clear.
1. WideMath Scientific Calculator — Best overall
Overview. WideMath’s calculator is a browser-based rebuild of the Casio fx-991ES PLUS. Same button layout, and 403 functions spread across the same eight MODE-menu entries: COMP, CMPLX, STAT, BASE-N, EQN, MATRIX, TABLE and VECTOR, plus the calculus functions that live under SHIFT. Results come back exact by default, so a fraction stays a fraction and √8 returns 2√2 rather than 2.828, with S⇔D for the decimal.
What we like. It’s the only tool on this list where you can solve a cubic equation, invert a 3×3 matrix, convert a value from binary to hex with bitwise AND/OR/XOR, and run a definite integral without ever leaving the page or switching tools. SHIFT and ALPHA work exactly like the physical unit’s yellow and red key functions, so if you already know a Casio, there’s effectively no learning curve. It also installs as a PWA, meaning it keeps working with no internet connection once loaded. That’s the detail that matters most for anyone using it during an exam or on a flight.
Drawbacks. The display writes on a single line, so you see 19/24 rather than a stacked fraction the way the physical unit shows it. And it’s a calculator, not a grapher. There’s no coordinate plane or plotted curves, so if you need to see a function’s shape, you’ll still want something like Desmos alongside it. History and stored variables live in the browser’s local storage, so clearing your browser data wipes them since there’s no account system to sync them.
Pricing. Free, no sign-up.
Best for: students and engineers who want their physical scientific calculator’s exact function set, minus the physical calculator.
Note. It’s published by WideMath, a hub of free browser-based math tools. The calculator used to be served from calculator.appynox.com, which now redirects to its WideMath home. There’s a Chrome extension too, which puts the same calculator in the browser side panel so it stays open next to whatever you’re reading.
2. Desmos Scientific Calculator — Best for pairing with a graphing tool
Overview. Desmos’s dedicated Scientific Calculator is clean, fast, and genuinely pleasant to type into. It covers trig, logs, powers, roots, and basic statistics.
What we like. The input feels natural, and if you need to switch to plotting a function, Desmos’s separate Graphing Calculator is one tab away and is arguably the best free graphing tool online.
Drawbacks. The Scientific Calculator specifically doesn’t do complex numbers, matrices, equation solving, or calculus. For any of that, you’re switching to a different Desmos product, or a different site entirely.
Pricing. Free.
Best for: anyone whose math work is mostly graphing, with occasional scientific-calculator arithmetic on the side.
3. Google’s built-in calculator — Best for quick everyday math
Overview. Type “calculator” into Google search and a scientific calculator widget appears directly in the results: trig, logs, exponents, a memory function, a degree/radian toggle.
What we like. Nothing to open, nothing to load. It’s already where you’re searching.
Drawbacks. No calculus, no matrices, no complex numbers, no equation solver, no base-N conversion. It’s built for “what’s 15% of 340,” not engineering coursework.
Pricing. Free.
Best for: the two-second calculation you’d otherwise reach for your phone’s calculator app to do.
4. GeoGebra Classic — Best for geometry and visual algebra
Overview. GeoGebra Classic bundles a graphing calculator, a geometry tool, 3D graphing, and a CAS (computer algebra system) calculator that handles symbolic calculus and algebra reasonably well.
What we like. The CAS can solve equations and integrate symbolically, and the geometry tools have no real equivalent on this list. If you’re teaching or learning visual math, GeoGebra is hard to beat.
Drawbacks. Complex numbers and matrix operations exist but live in a less obvious part of the interface than a dedicated MODE key would give you. There’s no base-N or bitwise arithmetic, and the interface targets classroom visualization over compact keypad-style entry.
Pricing. Free, with optional paid GeoGebra Classroom features for teachers.
Best for: geometry coursework, or anyone who thinks better in pictures than in equations.
5. Symbolab — Best for step-by-step homework help
Overview. Symbolab takes an equation and shows the working, not just the answer. That’s useful when the goal is understanding a method rather than just getting a number.
What we like. For algebra, calculus, and trig problems, the step-by-step breakdowns are genuinely good at explaining why, which none of the other tools here attempt.
Drawbacks. The free tier gives you the final answer only; the full step-by-step walkthrough sits behind a subscription. Base-N conversion and full matrix/vector operations aren’t part of the toolset at all.
Pricing. Free answers; steps require Symbolab Pro.
Best for: checking homework methodology, not replacing a calculator for quick computation.
6. Wolfram Alpha — Best for verifying answers and deep computation
Overview. Wolfram Alpha is less a calculator than a computational knowledge engine. Type a math expression, a physics formula, or even a chemistry question, and it computes an answer from Wolfram’s underlying engine.
What we like. For symbolic calculus, matrix operations, and complex numbers, the underlying math engine is arguably the most capable of anything on this list. It’s a good second opinion when you want to double-check a result.
Drawbacks. You’re typing math notation into a search box, not pressing calculator keys. There’s no MODE menu, no natural textbook input, no offline use. Detailed step-by-step solutions and extended computation time are gated behind Wolfram|Alpha Pro.
Pricing. Free for basic queries; Pro required for steps and larger computations.
Best for: verifying a result you got somewhere else, or exploring math beyond what a calculator interface is built for.
7. Microsoft Math Solver — Best for scanning handwritten problems
Overview. Microsoft Math Solver lets you type, write, or photograph a problem, including handwritten homework, and get a worked solution.
What we like. The OCR (photo-to-problem) feature is the best on this list. Point your phone camera at a textbook page and it recognizes the equation.
Drawbacks. It’s built around solving a specific problem you feed it, not general-purpose scientific computation. No base-N, no vectors, no MODE-style workflow for repeated calculation.
Pricing. Free.
Best for: homework where the problem is already written down somewhere and you need it solved and explained.
Honorable mentions
- Calculator.net Scientific Calculator: covers the basics competently but stops well short of matrices, complex numbers, or calculus.
- Casio’s own ClassWiz emulator: official, but it’s a marketing demo with a locked feature set, not a full working calculator.
- NumWorks web calculator: a nice emulator for NumWorks’ own hardware, though it mirrors that device’s more limited, non-natural-display function set rather than a fx-991ES PLUS-class one.
None of these three cleared enough of the ten-mode checklist to make the main list.
How to choose the right online scientific calculator
Ask yourself these before picking one:
- Do you need to plot a function, or just compute a value? If it’s plotting, start with Desmos or GeoGebra. If it’s computing (arithmetic, equations, matrices, calculus at a point), a full scientific calculator like WideMath’s will cover more ground.
- Are you replacing a physical calculator for an exam or coursework? Match the mode set to what your course actually requires (STAT? MATRIX? BASE-N?) rather than assuming any “scientific calculator” search result has it.
- Do you need it offline? Only a PWA-installable tool keeps working without a connection. Most of the tools above are online-only.
- Do you want the answer, or the method? Symbolab and Microsoft Math Solver are built to explain steps. A calculator is built to compute fast. Different jobs.
FAQ
Is a free online scientific calculator actually as capable as a real Casio fx-991ES PLUS? The closest match here is WideMath’s calculator, which replicates the same 403 functions across the same eight modes, including calculus, matrices, and base-N: the areas where most “scientific calculator” web tools stop short.
Can I use one of these calculators without an internet connection? Only if it’s installable as a PWA. WideMath’s calculator works offline once loaded; the rest require a live connection since they’re standard web pages or search-integrated widgets.
Do any of these require an account or payment? No. Every tool on the main list is free to use without signing up. Symbolab and Wolfram Alpha gate their step-by-step explanations behind paid tiers, but their basic answer output is free.
Which one handles complex numbers and matrices? WideMath, GeoGebra’s CAS calculator, and Wolfram Alpha all handle both. Desmos Scientific, Google’s calculator, and Symbolab’s free tier don’t.
Is there a calculator that converts between binary, octal, and hex with bitwise operations? Of the tools compared, only WideMath’s BASE-N mode does, with AND, OR, XOR, XNOR, and NOT included.
Do these work on mobile phones? Yes, all seven are responsive web tools that work in a mobile browser. WideMath and Microsoft Math Solver additionally support PWA installation for a more app-like experience.
This comparison reflects each tool’s published feature set as of mid-2026. Free calculators change their offerings occasionally, so if you spot something out of date, it’s worth a re-check before relying on it for an exam. For the full function reference and mode-by-mode walkthrough of our top pick, see WideMath’s calculator guides and documentation.