QuickCalci, or: I got tired of opening five tabs to do basic math

J Jaya Prakash — Mon, 20 Apr 2026 14:26:41 +0000

Hey all,

Been building something called QuickCalci and figured I'd share it here.

Honestly, it started out of pure frustration. Every time I needed to check a mortgage number or see what an SIP might return in ten years, I'd end up with three tabs open, none of them agreeing, and one of them usually wanting my email before showing me anything useful.

So I just put them in one place. 113 calculators, 14 categories. Free, no signup.

What's in it

The categories follow how I actually use the thing. Finance is the biggest bucket by a long way. SIP, EMI, mortgage, loan comparisons. Health is mostly BMI and calorie stuff. Education ended up bigger than I planned because I kept adding geometry and algebra formulas I couldn't remember from school. And there's a tax section, which I built mostly for myself around filing time when you just want a ballpark before you open Excel.

If browsing categories feels like too many clicks, there's a flat list of all 113 with topic chips on top. Type a name, filter, done.

A peek inside one

Most calculator sites give you a box and a number. That's the whole product. I wanted each tool to show its working a little, because usually when I'm doing this kind of math I'm also trying to understand something.

So every calculator has a few tabs instead of one form. There's a Formula tab that shows you the actual math and what each letter means. A Scenarios tab with presets you can load in one click (Home Loan 20yr, Car Loan 5yr, that kind of thing). A Try It Yourself tab with sliders and a live result, because filling in boxes is tiring. And a few more tabs for tips, examples and a deeper dive if you're curious.

The EMI one is where this clicks best. You slide the loan amount, change the rate, drag the tenure around, and the chart and summary update as you move. What I find weirdly satisfying is watching a 2-year bump in tenure quietly add a lakh or two to your total interest. That's the bit most people don't notice until they've already signed something.

Why I built it

Most calculator sites just annoyed me. Some are ad walls with a form hidden in the middle somewhere. Others look untouched since college websites still used Comic Sans. A couple have fine calculators but then paywall the "detailed" result behind a signup form.

I wanted something that doesn't make me squint on my phone at 11pm. Dark mode by default, works on mobile without me pinching to zoom, loads even when my connection is flaky. No signup. No popup asking if I want notifications.

Also, once the page loads, the math runs in your browser. So if your wifi cuts out mid-calculation (train tunnels, you know), it still works.

Stack, for the devs

Frontend is [React]. The math itself is plain JavaScript in the browser, so there's no server round-trip to multiply two numbers. For styling I didn't try to be clever. It's legible, you can tab through it with a keyboard, and it doesn't break on a small screen. I have an unreasonable grudge against sites that fall apart the moment you're not using a mouse.

What's next

I have a list of calculators I want to build, but I'd rather not guess. If there's one you keep googling every week that I don't have yet, drop it in the comments. Way more useful than whatever I'd come up with alone.

One ask: does it feel snappy on your phone? I've mostly tested on mine, so if it's crawling on yours I want to know.