Why we built WideMath, a true scientific calculator for your browser

My name is Anuj Paudel. I am a final-year computer engineering student at Pulchowk Campus in Kathmandu, and with my friends Ashish Pandey and Jhalak Prasad Pandey I build WideMath, a free scientific calculator that runs in any browser. People sometimes ask why we made another calculator when the internet already has hundreds of them. This post is my answer.

The calculator on the exam desk

In the engineering exams I sit, only one thing on the desk can compute: a handheld scientific calculator. No phone. No laptop. So students practise with that calculator the same way they practise formulas. You learn which key opens the equation solver. You learn that SHIFT gives the yellow functions and ALPHA gives the red ones. After a year or so, your fingers know the key sequence before your brain does.

The problem is that the calculator is not always with you. Maybe it is in the hostel. Maybe you are revising on a laptop at night and just want to check one answer. So you open a calculator in the browser, and it does not behave like the one you will use in the exam.

What goes wrong with most online calculators

When we looked closely at the free calculators online, the same problems came up again and again.

• Fractions turn into decimals. Type 3/8 + 5/12 and most of them show 0.7916666667. The answer your teacher wants is 19/24.
• Edge cases leak through. In degree mode, sin(180) should be exactly 0. Many web calculators show 1.224646799e-16, a leftover from the way computers store π. We wrote a whole guide on tests that expose a broken calculator.
• The exam topics are missing. Equation solving, matrices, complex numbers, binary and hex, regression, integration. Most "scientific" calculators online stop at sin, cos, log and square root.
• Ads. Moving banners and pop-ups on a page where you are trying to think.

None of this matters much for a quick sum. It matters a lot the night before an exam, when you are checking your working and the tool itself adds doubt.

What "true scientific" means to us

So we set a few rules for WideMath. We still check every change against them.

1. Exact answers first. Fractions stay fractions and surds stay surds. √8 gives 2√2, and 0.1 + 0.2 gives 3/10. Press S⇔D when you want the decimal.
2. All the modes, not only trigonometry. There are eight: COMP, CMPLX, STAT, BASE-N, EQN, MATRIX, TABLE and VECTOR. Between them they cover integration, derivatives, summation, matrices up to 3×3, vectors, complex numbers, statistics with regression, and quadratic, cubic and simultaneous equations.
3. The same keypad logic as a handheld. MODE, SHIFT and ALPHA work the way they do on the calculator in your bag, so the key sequence you practise here is the one you use in the exam hall.
4. Correct edge cases. sin(180) is 0. tan(90) is a Math ERROR, not a huge number.
5. Free, with no account and no ads.

How we built it, and the bugs we found in our own work

The first commits went in on 19 June 2026. Jhalak made the first concept design, and Ashish worked through a handheld calculator's user guide page by page: the keypad, the memory keys, the functions, keyboard input. I worked on the design, and later on the pages you are reading now, the guides and the translations.

The whole calculator is one web page. The heavy arithmetic uses math.js, an open source maths library, and everything happens on your own device. We count visits and a few button clicks with Google Analytics, but what you type into the calculator is never sent anywhere.

Then came the slow part, which was testing. In September we checked our answers against the documented behaviour of a handheld and found real bugs in our own calculator. In degree mode, sin(180) returned 1.224646799e-16 instead of 0, the exact mistake we were criticising in other tools. And 6÷2(1+2) returned 9, while the calculation order in the handheld manual we follow gives 1, because a multiplication written without its × sign is done before ÷. We fixed both and added automatic tests, 84 checks at the time of writing, so neither can quietly come back.

After that, the smaller things. The calculator works offline: once the page has loaded one time, your browser keeps a copy, so it opens even without internet. It is available in 14 languages besides English. And there is a Chrome extension that keeps the calculator open in the side panel while you read a PDF or watch a lecture.

Why it is free, and why there are no ads

A calculator page is a place where you are thinking. Ads that move, pop up or push the keypad down break that, so there are none. There is also no sign-up, because nobody should need an account to find a square root.

It does take our time. If WideMath saves you some of yours, there is a small Buy me a momo button on the calculator page. Momo is the dumpling most of Nepal runs on, so it felt like the right thing to ask for. That is the whole business model for now.

What comes next

WideMath is meant to grow into a set of free maths tools, and the scientific calculator is the first one. For now, most of our work goes into making this one calculator more correct, because a calculator that is right 99 times out of 100 is not good enough when the hundredth time is your exam.

If you find an answer that does not match your handheld, please write to [email protected] with the exact keys you pressed. That is the most useful message we can get.

Questions people ask us