Show HN: I Got Tired of Calculator Sites, So I Built My Own | Hacker News Reader

Show HN: I Got Tired of Calculator Sites, So I Built My Own

58 pointscalculatehow40 comments

I’ve always found that online calculators tend to have bad UIs, especially on mobile. Most of the calculator websites I’ve come across use outdated and inconvenient ways of inputting data, or they format the results in confusing ways.

I’ve noticed that fraction calculators (especially mixed fractions) are terrible to use, even on desktop. I haven’t built one of those yet, but it’s something I’m planning to tackle soon.

This is a project I’ve always wanted to work on, but I’m relatively new to this space. So far, I’ve created a collection of simple calculators focused on math and finance.

I’d really appreciate any feedback on the UI/UX or anything else you think could be improved.

You can try it here: https://CalculateHow.com

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I don't like that the loan calculator caps out at 50%, because the people most likely to want and need a simplified web interface are the ones most at risk of taking out batshit crazy loans (e.g. https://www.bigpictureloans.com/loan-rates).

For instance, check out this amortization table for one of those predatory lenders: https://www.calculator.net/amortization-calculator.html?cloa...

I'm capable of finding a working amortization calculator or banging it out on my HP-42s. You're capable of doing the math. The kind of people who can't do the math themselves are the ones who most need to see those numbers in front of their own eyes.

Good point. I need to work on balancing out the maximum number and how to display the results on mobile.

The biggest thing I'd want from a calculator -- having to calculate numeric expressions involving units, and getting the result in a specific unit. This is something I've used the google search prompt for because it can do these things to some degree, but google isn't a calculator and it will refuse to give you an answer right away if it doesn't think you entered a valid numeric expression.

Most of the time I'm looking for an answer in questions like:

    4 weeks + 59*3 hours in days
    1/2 * 36g * (900 m/s)^2 in joules

Other times when I'm working with memory and want to get a specific finite representation in hexadecimal:

    1 megabyte as hex

This might be off-topic because you're building a suite of calculators that I'd have to switch between to perform these tasks, rather than a single calculator that can do all / most of these things, but this kinda raises a point - if you want to switch between the calculators, maybe the UI should allow going from one to the other without performing the navigation, I'm thinking something like a sidebar that you can click on to switch to a different calculator.

Ideally when you switch and switch back the state should be saved because you might need to copy multiple values between calculators. EDIT: I forgot browsers have tabs, but still.

But really for me personally, nothing would beat a single thing that can do units and bases

Try https://numbat.dev/ (https://github.com/sharkdp/numbat). It's my go-to for any engineering calculations. It can also run locally.

  >>> 4 weeks + 59*3 hours -> days
  4 week + 59 × 3 hour  day
      = 35.375 day    [Time]

  >>> 5V / 50ohm -> mA
    5 volt / 50 ohm  milliampere
        = 100 mA    [Current]

Full syntax: https://numbat.dev/doc/example-numbat_syntax.html

I like numbat, but wish it supported rpn

Try qalculate. It's great with units and I think will work for base conversions, though I haven't tried that

The old TI-89 handheld calculators are amazingly good at this stuff. (It does struggle with "bytes", though it handles hex quite nicely within its syntax.) I still have one on my desk, and this is the main reason why. I barely bother with it for anything that doesn't involve units, and it's still worth the literal desk space. There is a good Android emulator, though in recent years it seems to have grown the habit of sometimes registering taps as a large number of button presses. I'm not entirely sure why; this behavior is very annoying. It might be phone-dependent, or a problem caused by a too-new Android version.

Frink is also very good at units, but I struggle to use it for anything more complex than a simple conversion. I'm sure it can do the task, but I've never been able to learn to drive it well, and usually get pretty frustrated when I try. The documentation and my brain don't really get along, or maybe it's that I am often in a hurry when I am trying to do something with it.

No you raise a great point. It's something I'm trying to solve. In the past, I've also had annoying issues where calculators didn't allow for multiple input types or wanted the input in a weird format. Good to know that more people have this problem. Thanks for sharing!

This is one of my favorite features of my old HP-50. You can attach units to numbers, and even define conversions between units.

What you want is WolframAlpha.com. Your examples[0][1] work out of the box.

[0] https://www.wolframalpha.com/input?i=4+weeks+%2B+59*3+hours+...

[1] https://www.wolframalpha.com/input?i=1%2F2+*+36g+*+%28900+m%...

This one is basically my daily driver for similar tasks: https://app.heynote.com/ (full app at https://heynote.com/). And it seems to work almost out-of-box for your first two examples, once you switch the buffer from "Plain-text" into "Math" mode.

It also supports switching between different buffers and some kind of local storage.

What is it about traditional calculator UIs that you don't like on mobile? I think they work great, unsurprisingly, since the form factor is similar. I have several (paid) mobile apps that fully emulate a traditional calculator model and I regularly use them.

To give some positive feedback: I like your loan calculator. That's something that could really be useful for a lot of people. I think there's still more you can do there, eg let people figure out how much credit they can afford with a given monthly payment. Take a look at traditional financial calculators like the HP 12c, they're extremely versatile in that regard.

Personally, I don't see the need for separate calculators for things like percentage increase or rounding numbers. Most of those could be combined in 2-3 apps at most, imho, scientific, financial and unit conversion. The others are really separate apps that would need a lot more functionality than the pure calculation aspect to really be useful (eg time tracking).

This is a good project with a nice clean UI and of course the nice lack of ads that calculator sites love to paint everywhere.

That being said, I do a lot of maths at my day job (and side job) and have found that now that I can ask my phone (gemini) math problems directly in an unsimplified form, its totally made online calculators irrelevant.

"Hey google, calculate the power loss of a 20 ohm resistor if it is R1 of an RC circuit with a 1u cap, an input frequency of 25kHz, and a rms voltage of 1.2V. Then make me an applet that shows the power loss with a slider for the input voltage from 1V to 12V, and a frequency slider for 25kHz to 250kHz."

I really cannot emphasize how helpful this is, and basically removed the need to seek out online calculators for common electronics calculations (which can now be folded into single custom calculations), which replaced the need to manually write out and solve the equations.

Thanks! You bring up a good point of new alternatives to calculators. Certain people don't need these calculator websites because assistants and even google can figure it out in the search engine results. I think calculators can play a role in helping the user understand what goes behind in a calculation.

Be careful doing that -- it's a great help (and I use LLMs for EE stuff too) but one thing LLMs still suck at is unit conversion. If you ever need to mix angular frequency (omega) and hertz, for instance, you'll need to tread VERY carefully. Same with anything involving gas laws, nuclear radiation, or vacuum tech, where there seem to be 20 different ways to express every quantity.

As for calculators, nothing I've found beats Jupyter QtConsole. It launches at startup and I have a hotkey mapped to bring up the window.

Very great calculator, good design, but it has too many functions. I advise you to add a "search" to find points, I also personally like the intuitive interfaces that are easy to understand even for beginners newbie.

Therefore, it may be necessary to add documentation.

In conclusion, the project is not bad, but I wanted the interface to be more user-friendly for beginners.

Thanks so much for the feedback! I'll definitely add a search bar in the future. I think the best UI's don't need documentation. Not saying mine is the best, but if you feel like I need documentation then I'm doing something wrong.

Yes bro, maybe I just misunderstood the interface a little, it's still great, but I wanted a simpler interface, it will attract more community to the site because it will be easier for people to understand what and how.

I hope your project turns out great and the community loves it.

I really like it. Good job! Please keep it ad-free/tracking-free. It's very rare in recent years ... for the same reason I built stringify.cc in recent weeks - https://news.ycombinator.com/item?id=44386194

So clever. I gave a UI idea to think about... What about instead of having to click to choose a calculator, have some of the most popular ones load automatically at the top are of the site, so users can directly perform those calculations without having to navigate to another page.

When and if the project gets more popular I'll definitely do something like this. Thanks for the suggestion!

You should check out this calculator here:

https://www.calculator.net/time-calculator.html

I use this at work all the time, but then I built my own customized calculator too.

On Firefox for Android on my phone, with the native keyboard the button to hide the keyboard is usually replacing the back button. With your own keyboard, the button to hide the keyboard is on the top right, but my muscles memory goes to hit the back button (which brings me back to the previous page rather than hiding the keyboard).

I'm not sure if that would be worth it to add an history element so that the back button can hide the keyboard, but for me that would make things more natural.

Thanks for the feedback! Yeah I wanted to create a custom keyboard because I felt that the native keyboards were missing some buttons that were useful like the +/- button. I don't want to take away from the native experience so thanks for letting me know.

Usability is a tough challenge and I especially like your clear explanations of how the calculations are done.

Having tried it on iPhone, a specific UI feedback I would have is making the page scrollable even when the numpad is displayed. I found myself typing the input, wondering where the output was, and not being able to scroll until I closed the numpad.

The UI is still wrong.

The perfect calculator is an LLM that calculates it for you.

/Jk (but really tho, like a nice Wolfram alpha)

No but I want to see a normal calculator immediately. Maybe some tabs that allow me to change functions.

Thanks! Can you elaborate more? Like a calculator that just has +, -, /, and x? What would the functions be?

The input UX is broken. There's no cursor.

Good catch. I need to add a cursor to the input box on mobile. Thanks!

Wow, that site is fast. Granted, I have a decent computer and fast internet, but I don't usually get that kind of speed. And the site is not super-lightweight either (it is React, not hand-crafted vanilla JS).

Must be some good optimization, good hosting, and little if any crap like trackers, ads, etc...

Thanks! I'm hoping to keep the website fast. I think it's important for the experience.

Can you add support for duplex numbers? (duplexnumbers.com)

I'm unfamiliar. Are duplex numbers specifically used in quantum computing?

Looks good. It's like a swiss knife. I love it.

As FerkiHN says, a search function sounds really powerful. I find timezone converter is really helpful. I work with 5 different timezones, and ask "when is 9AM <some timezone> in my timezone?" a lot. That would be a good idea for your next time calc.

Please checkout my work as well! https://news.ycombinator.com/item?id=44492131

Wow bro, this is just great, your project really deserves a star and I gave it, I also really liked that the utility is available locally.

By the way, I'm also a programmer and I create interesting things (my project is not ready yet) but I wanted to tell you about my PIT project.

This is a project for viewing photos directly in the terminal, it's very cool (I repeat, it's not ready yet), but could you please take a look at my repository, and if you want to award it a star just for assistance.

https://github.com/Ferki-git-creator/phono-in-terminal-image...

Just starred. Amazing work! As a side note, I think as a user, I'd love to see what would be the example of image view. The cli command definition looks good tho.

Bro, I've almost finished developing it, literally, because in 1 day I'll post the utility and show demo examples. Believe me, it's really worth a star, I'm shocked at what happened.

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