Almost every "best online calculator" list is a set of opinions about tools the author opened once. This one has a method, and it is stated below so you can disagree with it. The short version: the word "scientific" is doing almost no work in this market. Of the eleven calculators that rank for these queries, most cover trigonometry and logarithms and then stop, which is the feature set of a school calculator from 1985.
WideMath makes one of the eleven. It is in the table on the same terms as everything else, including the tests it fails and the things it does worse than the others. If you would rather ignore our entry, the recommendations below name a different tool for four of the six jobs.
On this page
How this was measured
On 6 September 2026 we pulled the live Google and Bing results for scientific calculator, scientific calculator online, casio calculator online, fx-991es plus calculator online and scientific calculator casio online with shift solve, then took every distinct tool that appeared. That is the eleven below. It is a list of what people actually reach, not a list of what we like.
For each one we opened the tool and checked, by using it, whether the mode exists at all. "No" in the table means we could not find the feature, not that we disliked it. Then we ran the same six-test accuracy battery on each, described in our guide to spotting a broken online calculator.
Two honest limits. Client-rendered tools like Desmos and GeoGebra ship almost nothing to a page fetcher, so their feature checks were done by hand in a browser rather than from source. And several of these sites change weekly, so treat the table as a snapshot dated above, not a permanent fact.
Best tool for each job
There is no single winner, and any list that names one is not paying attention. Pick by what you are doing.
| If you are doing this | Use | Why |
|---|---|---|
| Plotting or exploring a function | Desmos or GeoGebra | Genuinely excellent graphing. Neither does matrices, complex numbers or base-N in its scientific calculator. |
| Algebra with worked steps | Symbolab | Shows the working. The step by step output is largely paywalled, so budget for that. |
| A quick sum in a hurry | Your OS calculator, or calculator.net | Opens instantly. calculator.net is a 144-word page with a keypad and no ceremony. |
| Practising on a Casio keypad for an exam | A full mode engine such as ours, calculator.now or mathda | You need MODE, SHIFT and ALPHA to behave like the hardware, which the graphing tools do not attempt. |
| Matrices, complex numbers or base-N | Ours, mathda or calculator.now | Most of this list simply does not have these modes. |
| Scanning a handwritten problem | mathda | It has an OCR scanner. Nothing else here does, ours included. |
What each one can actually do
The columns are the modes a physical Casio fx-991ES PLUS has. This is the table that separates the category, and it is the one nobody publishes.
| Calculator | Trig & logs | Calculus | Matrices | Complex | Base-N | Equations | Stats |
|---|---|---|---|---|---|---|---|
| WideMath (ours) | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| mathda (CalcES) | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| calculator.now Casio | Yes | Partial | Yes | Yes | Yes | Yes | Yes |
| Symbolab | Yes | Yes | Yes | Yes | No | Yes | Yes |
| calculory Casio-style | Yes | Partial | No | No | No | Partial | Partial |
| Desmos scientific | Yes | No | No | No | No | No | Partial |
| GeoGebra scientific | Yes | No | No | No | No | No | Partial |
| calculator.net | Yes | No | No | No | No | No | No |
| scicalc.org | Yes | No | No | No | No | No | No |
| scientificcalculator.dev | Yes | No | No | No | No | No | No |
| morecalculators Casio | Yes | No | No | No | No | No | No |
Six of the eleven do trigonometry and logarithms and nothing else on this list. That includes two of the three tools Google puts at the very top for "scientific calculator". If your work involves a matrix, a complex number or a hex conversion, most of the first page of results cannot help you at all.
The accuracy tests
Feature lists are easy to write and hard to verify. Arithmetic is the opposite. These are the tests from our broken calculator guide, and you can run them on anything in about thirty seconds.
| Type this, in degree mode | A careful calculator shows | A careless one shows |
|---|---|---|
sin(180) | 0 | 1.224646799e-16 |
cos(90) | 0 | 6.123233996e-17 |
tan(90) | Math ERROR | 1.633123935e+16 |
70! | Math ERROR | 1.19785717e+100 |
171! | Math ERROR | Infinity |
| Look for a mode indicator | A visible D, R or G | Nothing at all |
The last one is the most practical and the most skipped. A calculator that will not tell you whether it is in degrees or radians will eventually hand you a confidently wrong answer with no way to notice.
Our own results on all six, plus the one test where we differ from a physical Casio, are published in full in that guide. We had two failures ourselves until this week and say so there.
What "truly scientific" means
Search for "scientific calculator" and most of what you get, including some very large names, is a four-function calculator with trigonometry and logarithm keys added. That was the definition in about 1975. A calculator that deserves the word today does all of this:
| Capability | Basic "scientific" calculators | A genuinely scientific one |
|---|---|---|
| Trigonometry, logarithms, powers, roots | Yes | Yes |
| Exact fractions and surds (√8 gives 2√2) | Rarely | Yes |
| Definite integration and differentiation | No | Yes |
| Summation of series | No | Yes |
| Matrices and vectors | No | Yes |
| Complex numbers, rectangular and polar | No | Yes |
| Equation solving, quadratic to simultaneous | No | Yes |
| Statistics with regression | No | Yes |
| Base-N and bitwise operators | No | Yes |
Exact results deserve a line of their own, because it is the difference you notice first. On a tool that keeps results exact, 1÷2+1÷3 returns 5/6 rather than 0.8333333333, and √8 stays 2√2. Once a value collapses to a decimal you cannot get the exact form back, and errors compound quietly from there.
Notes on each calculator
Desmos
The best free graphing tool on the web, and its scientific calculator is clean and fast. It has no matrices, no complex numbers, no base-N and no equation solver. Use it to see a function, not to sit an exam.
GeoGebra
Similar shape to Desmos, with an unusually deep classroom ecosystem and 71 language versions. Same limits on the scientific calculator itself.
calculator.net
A 1998 domain and a 144-word page. It loads instantly, does the basics correctly, and makes no attempt at the advanced modes. For a quick sum it is genuinely hard to beat.
Symbolab
The strongest algebra engine here, and the only one that shows real worked steps. Those steps are largely behind a subscription, which is the honest catch. Available in thirteen languages.
mathda (CalcES)
The closest thing to a direct rival for Casio-style work: full mode engine, a natural textbook display, and an OCR scanner for photographing a problem, which nothing else here has. Ships nine locale versions.
calculator.now
A full mode engine inside an enormous network of single-purpose tools, and twenty-six language versions. Carries advertising.
calculory
A Casio-style simulator on a domain registered in March 2026, and the most carefully built page in this set: a worked example, a model comparison against the TI-84, a methodology block with a visible review date. Its mode coverage is thinner than its presentation suggests.
scicalc.org, scientificcalculator.dev, morecalculators
Three lean, fast, ad-supported calculators that cover the basics well. None attempts the advanced modes. scientificcalculator.dev is worth noting as the tool Google puts first for several Casio queries despite having no structured data at all.
WideMath, ours
Eight modes, exact results, no advertising, no account, and it works offline once loaded. What it does not have: an OCR scanner, graphing, step by step algebra, or any language but English and Spanish. It is also by far the youngest domain here, so it has no track record to point at.
If you need graphing, use Desmos. If you need worked steps, use Symbolab and expect to pay. If you need a Casio keypad with matrices, complex numbers and base-N, you are choosing between about three tools on this whole list, and you should run the six accuracy tests before trusting any of them, including ours.
Frequently asked questions
What is the best free online scientific calculator?
It depends on the job. Graphing: Desmos or GeoGebra. Worked steps: Symbolab, though they are largely paywalled. Casio-style exam practice with matrices, complex numbers and base-N: a full mode engine, which most popular results do not have. Judge any candidate on whether those modes exist at all, then on whether sin(180) returns 0.
What makes a calculator truly scientific?
Trigonometry and logarithms are the entry bar, not the definition. Add calculus, summation, matrices and vectors, complex numbers, equation solving, statistics with regression, and base-N with bitwise operators. Six of the eleven tools here stop at the entry bar.
Is Desmos a scientific calculator?
It is an excellent graphing calculator and a competent scientific one, but it has no matrices, complex numbers, base-N or equation solver. Right tool for visualising a function, wrong one for exam-style calculation.
Which online calculators are accurate?
Test rather than trust. In degree mode sin(180) and cos(90) should both be 0, tan(90) should error, and 70! should be out of range on a Casio-style tool. An answer of 1.224646799e-16 means raw floating point is reaching the display.
Do I have to pay for a good one?
No. Every calculator here is free to use. The paid parts are step-by-step solutions on the algebra solvers, and Casio's own ClassWiz emulator on ClassPad.net. Casio offers no free browser emulator of the fx-991ES PLUS, and its older free service keisan.casio.com closed on 20 September 2023.
Run the tests on ours first
Eight modes, exact results, no account. Start with the test most calculators fail.
Open the calculator with sin(180) loaded →