Stock Calculator 2.0: rebuilt from the ground up

If stockcalculator.io looks sharper today, that’s because everything behind it is new. Version 2.0 is a complete rebuild — new engines, new pages, new content — while keeping every part people actually loved: the multi-trade position calculator, dark mode by default (“like Bloomberg Terminal”, as the old site put it), the b/s keyboard shortcuts, and shareable links. Old ?data= links keep working — they decode on arrival and quietly become new-format URLs.

What changed

The math is now exact. Most calculators compute in binary floating point, which is how tools end up claiming your cost basis is $110.50000000000001. Our engines keep every value as an exact ratio of integers and round exactly once, at display — currency amounts to each currency’s convention, percentages to the precision you pick with the spreadsheet-style .0← / .00→ buttons. A golden test suite locks the behavior on every change; one documented exception (CAGR’s irrational root) is spelled out on the about page.

Six intent tools join the flagship. The position calculator still anchors the homepage — trade rows you can add, clone, and flip with a keystroke; fees in $ or %; seven display currencies; an optional illustrative tax rate. Around it: stock profit, stock average with a target-average solver (tell it the average you want, it tells you the shares it takes), position size, risk/reward with break-even win rate, dividend/DRIP with a year-by-year table, CAGR that solves any of its four variables, and break-even plus the loss-recovery table.

It’s noticeably faster. Every page opens with a worked example already on screen — nothing to wait for before you start typing — and once a page has loaded, the calculator keeps working even if your connection drops.

Content that earns its place. A 15-question FAQ, rebuilt guides, and new research-cited articles — every empirical claim linked to peer-reviewed work by DOI, starting with the disposition effect and what trading costs do to returns. Educational throughout: nothing here is advice, and the about page says so precisely.

“Cool trade ideas” grew up. The scenario gallery is now Worked examples — the Buffett/AAPL position, the 2017→2021 bitcoin round trip, and the Tesla DCA sequence, re-encoded to the new link format, plus three pedagogical setups. Historical scenarios for exploring the math — not recommendations.

What didn’t change

Dark mode is still the default (light is one click away and remembered). b and s still flip a trade’s direction. Links still carry whole calculations. The math still runs entirely in your browser — no accounts, no market data, and your numbers never leave your device. And every old URL — locale pages included — redirects permanently to its successor in a single hop.

Found something off? The changelog will show fixes as they land — 2.0 is a foundation, and the article roster building on it is already scheduled.