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.

How do I convert metric to imperial units?

Pick the category, type your value, and choose the units on each side. Conversions go through the SI definition of each unit — 1 inch is exactly 2.54 cm, 1 pound exactly 0.45359237 kg — so 1 metre converts to 3.28084 feet and 1 kilometre to 0.621371 miles.

How is temperature converted?

Temperature scales have different zero points, so conversion is a shift and a scale, not a simple ratio: °F = °C × 1.8 + 32 (so 0 °C = 32 °F and 100 °C = 212 °F), and K = °C + 273.15. This page handles the offset correctly for Celsius, Fahrenheit and Kelvin.

Why do KB and KiB both exist?

Storage vendors use decimal prefixes (1 KB = 1000 bytes, 1 GB = 1000³ bytes) while operating systems often use binary prefixes (1 KiB = 1024 bytes, 1 GiB = 1024³ bytes). The data-size category offers both, so 1 GB converts to about 0.9313 GiB.

Can I convert in both directions?

Yes — the converter is bidirectional. Type on the left to convert left-to-right, or type in the right box to convert back the other way. The Copy button copies the right-hand result.

Does the unit converter need an internet connection?

No. Every conversion factor is a constant bundled in the page's JavaScript. Nothing is uploaded and nothing is fetched — it works offline once the page has loaded.

General

Unit Converter

Convert length, mass, temperature, speed, area, volume, and data-size units — live, bidirectional, offline.

Unit Converter

Physical units — length, mass, temperature, speed, area, volume, data size. Edit either side.

FromUnit

To (edit to convert back)Unit

1 m = 3.2808399 ft

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

How to use this calculator

Pick a category tab (length, mass, temperature, speed, area, volume, data size).
Type a value on the left and choose the units on both sides.
Edit either side to convert in the other direction; copy the result with one tap.

Bookmark Unit Converter — it works offline once loaded. Figures are decision aids, not financial advice.