CalcFi

CalcFi is a free web-based collection of financial calculators that helps you understand how different parts of your finances connect. You can calculate things like mortgage payments, paycheck take-home amounts, debt payoff timelines, and retirement savings. The unique part is that CalcFi cross-checks these numbers against each other. For example, if you increase your mortgage payment, it will show you how that change might push back your planned retirement date. This gives you a more complete picture of your financial health, rather than looking at each calculation in isolation.

All the math happens directly in your web browser. Your personal financial data is never sent to CalcFi's servers; it stays on your device. The tool sources its formulas and live data—like tax brackets and interest rates—directly from official U.S. government agencies like the IRS, the Federal Reserve, and the Bureau of Labor Statistics. You can save your calculations locally, and when the underlying federal data updates, your saved numbers will reflect those changes so you can see what's moved.

This tool is useful for anyone making significant financial decisions, such as someone buying a home who wants to see the long-term impact on their budget, a freelancer estimating quarterly taxes, or a family planning to pay off credit card debt while saving for retirement. Because it's free, private, and based on authoritative data, it's a practical first step for financial planning before consulting a professional advisor.