Are my financial numbers uploaded to a server?

No. CalcTools is 100% client-side. Every calculation — mortgage, loan, compound interest, tax — runs in your browser as plain JavaScript. There is no backend and no /api route. The site's Content-Security-Policy (connect-src 'self') even restricts which hosts the page may contact, so the privacy guarantee is enforced by the browser itself.

Are the calculations accurate?

Yes — each calculator uses the standard, published formula for its problem (the loan PMT formula, compound-interest future value, marginal tax bands, the HKMA stress-test rule, and so on). The verify suite hand-checks reference values against the implemented math before every build. Still, these are decision aids, not financial advice; confirm with a professional for a binding decision.

How is the currency converter's exchange rate sourced?

The converter ships with a build-time snapshot of exchange rates (taken from a public, no-key exchange-rate API at build time) bundled same-origin — it never makes a runtime request to any server in this MVP build. So currency conversion works offline and exposes no browsing data to a third party.

Do the Hong Kong calculators reflect the current year?

They use the published 2024/25 HK rates: Salaries Tax progressive bands (2%/6%/10%/14%/17%) and 15% standard rate with a $132,000 basic allowance; property Stamp Duty on the smoothed ad valorem band scale; MPF at 5% employee + 5% employer capped at the $30,000 monthly relevant-income limit. Always confirm the current figures on gov.hk before relying on a number for a real filing or purchase.

Does it work offline?

Yes. After the first load the app shell is cached, so every calculator works with no internet connection. Install CalcTools as a PWA and it opens and runs offline.

Business

Break-Even Calculator

How many units you must sell to cover fixed and variable costs — the break-even point.

Break-Even Calculator

How many units you must sell to cover your fixed and variable costs.

Fixed costs

Price per unit

Variable cost / unit

Your numbers never leave your device — all math runs in your browser.

Result

Break-even point

500 units

Revenue at break-even$25,000.00

Contribution margin / unit$20.00

Break-even units = fixed costs ÷ (price − variable cost). Below this volume you operate at a loss.

Printable PDF report, saved scenarios & compare are Pro features.

One-time unlock, no subscription. Unlock CalcTools Pro →

How to use this calculator

Enter your fixed costs (rent, salaries, etc.).
Enter the price per unit and the variable cost per unit.
Read the units you must sell to break even and the revenue at that point.

Bookmark Break-Even Calculator — it works offline once loaded. Figures are decision aids, not financial advice.