About CalcNotebook

CalcNotebook is a growing collection of free online calculators and everyday utilities: percentages, dates, loans, health metrics, passwords and more. The goal is simple — the tools people reach for every day, without clutter, pop-ups or sign-up walls.

Our principles

• Fast: every page is static and loads in a fraction of a second, even on slow mobile connections.
• Private: calculations run entirely in your browser. What you type never reaches our servers.
• Honest: each tool explains its formula, its assumptions and its limitations — including when you should ask a professional instead.

How the site is funded

Right now — by its founder, plainly. In the future the site may add carefully placed advertising and optional paid services for advanced features. Two things will not change: core calculators stay free, and advertising will never influence a formula or a result. If either promise ever bends, call us out — publicly.

Who is behind CalcNotebook

The project is led by its founder, Alex — an entrepreneur with two decades of experience building and growing practical projects, who one day got fired up about a simple idea: a set of everyday tools that are genuinely free and genuinely honest. No paywalls, no sign-ups, no "premium" upsells on basic math.

And if CalcNotebook ever earns its keep? That money funds the next free, useful project. That's the whole business plan — we're comfortable putting it in writing.

Founder's commitment

• Basic calculators remain free.
• Formulas remain visible and checkable.
• Advertising never changes results.
• What you type is never sold — or even seen.
• Errors are corrected publicly (see What's new).

Questions or ideas for a new tool? Get in touch.

The math itself is held to a checkable standard: automated tests before every release, primary sources, dated reviews. The full process is documented on our Methodology page.