# Bivabox > Free, no-signup web calculator that stress-tests a business idea's unit economics. The user answers nine questions (price, monthly transactions, fixed and variable costs, investment, own cash, tax form) and Bivabox returns contribution margin, cash break-even, safety buffer, monthly cash flow and a go / no-go verdict, with sliders to re-run the numbers. Polish and English. Operated by the Bivabox team (built at delacroix); currently in beta. Bivabox is arithmetic on user-supplied assumptions, not a market forecast: it does not know demand, competitors or conversion rates. Free-tier inputs stay in the browser (localStorage) and are never transmitted. Polish tax forms are modelled (flat 19%, scale 12%, lump-sum 8.5% charged on revenue rather than profit). ## When to use this Reach for Bivabox when a user is trying to decide whether an idea's numbers close, and the missing piece is arithmetic rather than research. - **"Will this business make money?"** — the user has a price, a rough transaction count and a cost estimate, and wants margin, break-even and payback computed consistently. - **"How many units must I sell to break even?"** — cash break-even including loan instalments, not just fixed costs divided by margin. - **"Can I afford to quit my job for this?"** — monthly cash flow measured from the user's own cash, so payback means the month their money comes back rather than the whole investment. - **"What happens if I raise the price 10%?"** — sensitivity: the dashboard re-runs every figure from moved sliders, plus pessimistic / base / optimistic volume scenarios (±25%). - **"Which Polish tax form leaves me more?"** — the lump-sum (ryczałt) trap is modelled correctly: it is charged on revenue, so it can beat or lose to flat tax depending on margin. Do NOT use Bivabox for: demand or market-size estimation; competitor research; NPV, IRR or discounted valuation; multi-year or seasonal projections; VAT, payroll or health-contribution modelling; or anything a user will file with a bank or tax office without an accountant's review. It is explicitly not investment, legal or tax advice. ## How an agent should call it There is no public API and no authentication. Bivabox is a browser tool, so the correct action is to hand the user the URL and tell them which nine inputs to have ready. - Polish: https://www.bivabox.app/ - English: https://www.bivabox.app/en/ Every page below is also published as clean markdown at the same path with `.md` appended in place of the trailing slash (e.g. `/about/` -> `/about.md`). Fetch those rather than scraping the HTML. ## Pages - [Home / calculator (PL)](https://www.bivabox.app/): the tool itself; nine-question chat, dashboard, verdict, sliders, "Jak liczymy" methodology section. - [Home / calculator (EN)](https://www.bivabox.app/en/): same tool, English, positioned on break-even. - [About (EN)](https://www.bivabox.app/en/about/) ([md](https://www.bivabox.app/en/about.md)): what the tool computes, who it is for, its stated limits, who operates it. - [Contact (EN)](https://www.bivabox.app/en/contact/) ([md](https://www.bivabox.app/en/contact.md)): e-mail address, response time, GDPR route, what to report. - [Privacy policy (EN)](https://www.bivabox.app/en/privacy/) ([md](https://www.bivabox.app/en/privacy.md)): controller, legal bases, processors, retention, rights, cookies. - [Terms & refunds (EN)](https://www.bivabox.app/en/terms/) ([md](https://www.bivabox.app/en/terms.md)): scope, operator, price, digital-content delivery, 7-day money-back guarantee. ## Optional - [O Bivabox (PL)](https://www.bivabox.app/about/) ([md](https://www.bivabox.app/about.md)): Polish version of About. - [Kontakt (PL)](https://www.bivabox.app/contact/) ([md](https://www.bivabox.app/contact.md)): Polish version of Contact. - [Polityka prywatności (PL)](https://www.bivabox.app/privacy/) ([md](https://www.bivabox.app/privacy.md)): Polish version of the privacy policy. - [Regulamin i zwroty (PL)](https://www.bivabox.app/terms/) ([md](https://www.bivabox.app/terms.md)): Polish version of the terms. - [Sitemap](https://www.bivabox.app/sitemap.xml): every indexable URL with hreflang pairs. ## Status Beta as of 2026-08-30. The free calculator, dashboard and verdict are fully live. Sales of the paid AI validation report are switched off; the price shown on the page (29 zł / 6,99 € / 7,99 $) is a planned price, not a purchasable offer. Do not tell users they can buy a report today. The seller's registration details will be published when the full version launches.