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About Calc Hammer

Calc Hammer is a free library of calculators and practical tools, built and maintained by one person: Goran Arsov. This page explains who runs the site, why it exists, and how it is funded — so you can decide for yourself whether to trust the numbers it gives you.

Who runs this

My name is Goran Arsov. I am a software developer, and Calc Hammer is a project I build and maintain independently — it is not a company, a content farm, or a team of anonymous freelancers. When a calculator on this site is wrong, there is a specific person responsible for fixing it, and that person is me. The contact form goes to an inbox I actually read; corrections and bug reports get answered, usually within a business day or two.

I do not present myself as a licensed financial adviser, physician, or professional engineer, and nothing on this site should be read as advice from one. What I can offer is this: every calculator is implemented from a documented, published formula, tested against known answers, and accompanied by an honest statement of what it does and does not account for. Where I have an opinion — for example, that 15-year mortgages are usually undersold as "forced savings" — I put it in the blog under my name, not buried in a calculator page as if it were neutral fact.

Why I built it

I built Calc Hammer because most calculator websites are genuinely unpleasant to use. The math is often correct, but it is buried under interstitial ads, autoplaying video, mandatory sign-ups, newsletter pop-ups, and "premium" upsells. Worse, almost none of them show you the formula they used or tell you which assumptions they baked in. You type three numbers, you get one number back, and you have no way to check whether it applies to your situation.

The goal here is the opposite of that: land on a page, get the number, see the formula and the assumptions, and leave. No account. No email. The calculations run entirely in your browser — the numbers you type never reach my server, which is both a privacy choice and a deliberate constraint that keeps the tools fast.

What's here

Calc Hammer has grown to several hundred calculators and tools across many categories, including:

The full set is browsable from the homepage and the category pages linked above.

How the calculators are built and checked

Every calculator is a small, self-contained piece of code with its own automated test suite — tested against textbook worked examples, edge cases (zeros, very large and very small inputs, boundary conditions), and plausibility ranges. The full methodology — which formulas are used, where they come from, how accuracy is verified, the limits of each category, and how to report an error — is documented in detail on the Methodology page. If you are going to rely on a number from this site for a real decision, read that page first.

The calculators produce estimates for informational purposes, not professional advice. The Disclaimer states the limits in full. For anything load-bearing, regulated, or medical, the right move is always to confirm with a qualified professional.

How Calc Hammer is funded

Calc Hammer is free and is funded by advertising through Google AdSense. That is the entire business model — there is no paid tier, no data sale, no affiliate-driven calculator output. Advertisers have no influence over which calculators I build, which formulas I use, or which results they return. Ads are kept deliberately light and never block or interfere with a tool's functionality; if a calculator would work better without an ad in a particular spot, the ad does not go there.

Because the site shows ads, the Privacy Policy explains exactly what third-party advertising cookies do and how to opt out, and a consent banner lets you decline non-essential cookies with no loss of functionality.

Other projects

Calc Hammer is not the only thing I run. I also publish Fresh Jots, a separate site for notes and writing that doesn't fit the calculator-and-formula format. I mention it here for transparency — same person behind both, same editorial standards.

Contact and corrections

Found a calculator that returns a wrong number? Spotted a typo, a broken link, or an assumption that should be stated more clearly? Want a calculator that does not exist yet? Please get in touch. Include the page URL and, for a suspected error, the inputs you used and the answer you expected (with a source if you have one). Reported errors get investigated and fixed, and I am happy to credit the person who reported them.

Calc Hammer is built and maintained by Goran Arsov. Editorial standards and formula sources are documented on the Methodology page; last site-wide editorial review: May 14, 2026.