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.

Hong Kong

HK Property Stamp Duty Calculator

Hong Kong ad valorem stamp duty on a residential property by the smoothed band scale.

HK Property Stamp Duty Calculator

Hong Kong Scale 2 residential stamp duty (eff 28 Feb 2024), $100 concession up to HK$4M, smoothed bands to a 4.25% top.

Property value (HK$)

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

Result

Stamp duty payable

HK$100.00

Effective rate 0.00%

Applicable band≤ HK$4,000,000 (HK$100 concession)

Scale 2 residential (effective 28 Feb 2024; BSD/SSD/NRSD abolished), flat HK$100 concession up to HK$4,000,000 (raised from HK$3M in the 2025-26 Budget), nominal rates 1.5%/2.25%/3%/3.75%/4.25% top, smoothed at band edges. Decision aid — confirm on gov.hk and check whether any special-duty surcharge applies before a real purchase.

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How to use this calculator

Enter the property value in HK$.
Read the stamp duty payable and the effective rate.
Check the applicable band to see which scale applies.

Bookmark HK Property Stamp Duty Calculator — it works offline once loaded. Figures are decision aids, not financial advice.