About the founder

ListCalc is built and maintained by one person. This page is who that is, and how the numbers on this site get checked.

Hi — I'm Toukir Ahmed

I'm a web developer based in Bangladesh, and I build and run ListCalc on my own. There is no team behind this site. I'm a developer, not a licensed financial adviser or clinician — so ListCalc doesn't give advice. It applies published, citable formulas and shows its working, so you can check the result rather than take my word for it. If a number on this site is wrong, it's mine to fix, and I want to hear about it: hello@listcalc.com.

Today ListCalc has 249 calculators across 10 categories — finance, health, math, everyday, construction, electrical, business, conversion, gaming and more — alongside 59 explainer guides.

Why I built it

Calculator sites tend to make you choose: fast but shallow, or thorough but buried under pop-ups, cookie walls and "unlock your full results" prompts. I didn't think that trade was necessary. I wanted a calculator that opens instantly, computes as you type, shows the formula it used, and then gets out of the way.

The privacy part came from the same instinct. You shouldn't have to hand your salary, your weight or your loan balance to a stranger's server to divide two numbers.

How the site is built

ListCalc runs entirely on Cloudflare Workers with a key-value store. There is no origin server, no framework and no build step — pages are assembled at the edge and served from wherever you are.

Every calculation is plain JavaScript running inside your browser. Nothing you type is sent anywhere as you type it, because there is nowhere for it to go: no calculation ever makes a network request. That's an architectural fact you can verify in your browser's network tab, not a promise in a policy document.

It also means the site installs as an app and keeps working with no connection. The privacy policy spells out exactly what is and isn't stored.

How I check the numbers

Formulas come from published, citable sources — amortization mathematics for loans, WHO categories for BMI, published engineering references for construction and electrical work. Where a formula has known limits, the page says so rather than implying precision it doesn't have.

I'm currently building an automated test suite that runs every calculator against independently derived expected values, starting with the electrical and payroll tools where an error costs the most. The methodology page states plainly how far that coverage currently reaches — including where it doesn't yet.

What I'm not

I'm not a licensed financial adviser, accountant, electrician or clinician. ListCalc gives you estimates and shows its working so you can check it — for anything consequential, talk to a qualified professional. The disclaimer covers where the limits sit for each category.

Get in touch

Found a calculation that looks wrong? Want a calculator that doesn't exist yet? Email me directly at hello@listcalc.com or use the contact form. Verified corrections ship fast and get noted on the page.

Every calculator on ListCalc can also be embedded on your own site for free.