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

kstrauser · 2 months ago

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.

calculatehow · 2 months ago

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

flysand7 · 2 months ago

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

Ao7bei3s · 2 months ago

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

paradox460 · 2 months ago

I like numbat, but wish it supported rpn

tjelen · 2 months ago

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.

onedognight · 2 months ago

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%...

exmadscientist · 2 months ago

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.

calculatehow · 2 months ago

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!

paradox460 · 2 months ago

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

ttshaw1 · 2 months ago

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

t_mann · 2 months ago

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).

Workaccount2 · 2 months ago

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.

CamperBob2 · 2 months ago

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.

calculatehow · 2 months ago

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.

FerkiHN · 2 months ago

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.

calculatehow · 2 months ago

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.

FerkiHN · 2 months ago

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.

lukaslukas · 2 months ago

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

zahirbmirza · 2 months ago

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.

calculatehow · 2 months ago

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