Why FinCalcKit exists
Most online financial calculators answer one narrow question — "what's my monthly payment?" — and stop there. In practice, the decisions people actually face are more specific: should I refinance now or wait? Is paying off this card or that one first faster? When does PMI actually drop off my mortgage? FinCalcKit is built around those specific, real-life questions.
Who builds FinCalcKit
FinCalcKit is built by Philip Grant, who has spent his career in finance and financial analysis. With a background in business and economics, he started out in the financial markets trading U.S. equities, then spent years in financial analysis and planning at a large engineering and infrastructure company — building financial models, forecasting and managing multi-million-dollar budgets, analyzing cash flow, and evaluating the returns on capital investments worth billions before leadership signed off on them. Today he is the founder and CEO of his own company.
Years of running the numbers behind real financial decisions are why FinCalcKit's calculators are built around decisions rather than generic formulas — extra mortgage payments and PMI, trade-ins and rebates, tax-bracket-aware Roth conversions. They're the same "what actually happens if I do X?" questions he has spent his career answering, now free for anyone to use.
How the calculators are built
Every calculator uses standard, well-established financial formulas — amortization, compound interest, present and future value — combined with current public rules where they apply. For example, the income-tax and Roth conversion tools use published IRS federal tax brackets, and the mortgage tools apply the federal Homeowners Protection Act, which requires lenders to cancel PMI once the loan balance reaches 78% of the home's original value. The formulas and reference figures are reviewed periodically and updated as rules change.
Your privacy
Every calculator runs entirely in your browser using JavaScript. Nothing you type is sent to a server, stored in a database, or shared with anyone. Close the tab and everything you entered disappears — that's by design.
Accuracy and limitations
Every calculator produces an estimate based on the numbers and assumptions you provide — it isn't personalized financial, tax, or legal advice. For important decisions, confirm the details with a qualified professional. See our Terms of Use for more.
Questions or feedback
If you spot something that looks wrong, or have an idea for a calculator that would help you, visit the Contact page.
Last reviewed: June 2026 · Written by Philip Grant