About the Author: Wanli Lu

First-hand experience

Every calculator on this site was built to solve a problem I actually had — splitting a bill, checking whether an extra mortgage payment was worth it, converting a salary to an hourly rate, sanity-checking a tax estimate. I wrote the formulas, implemented them in code, and verified the output against hand calculations and independent references before publishing. The experience here is hands-on building, not borrowed content.

How I keep the math accurate

Each calculator is a small, pure function covered by automated tests. Before any page goes live — and again on every update — a test suite checks known inputs against known results (for example, a $300,000 loan at 6.5% over 30 years should return a monthly payment of $1,896.20). If a number is wrong, it's flagged as a bug and fixed, never shipped as "close enough."

This is the part I care about most: a calculator you can't trust is worse than no calculator.

What I cover

• Personal finance: loans, mortgages, EMI, amortization, savings, retirement, compound interest.
• Tax & business: income tax, sales tax, VAT/GST, profit margins, ROI and ROAS.
• Everyday tools: unit and currency conversion, BMI, TDEE, dates.
• Guides: plain-language explainers that walk through the formulas with worked examples.

How to reach me

If you spot an error, want a tool added, or have a correction, email [email protected]. I read every message and fix verified issues promptly. You can also use the contact page.

An honest disclaimer

I'm not a licensed financial adviser, tax professional, or physician. Calcuxa is a set of computational tools and educational explainers, not professional advice. For decisions that materially affect your money or health, confirm the result with a qualified professional. Every finance page states this clearly.