Calculator Methodology

Estimates, not decisions

A FinanceAvatar result is an educational estimate based on the numbers you enter and the assumptions listed on that page. It is not a quote from a lender, an official tax computation, or a recommendation. Two people can enter similar inputs and still face different real-world terms, fees, taxes, or eligibility rules.

Math separated from the interface

Calculator formulas will live in dedicated TypeScript modules, not mixed into buttons and layout code. That makes it easier to review a formula, reuse it across related tools, and describe it in writing. The page should then show the result, a breakdown, and an explanation of what the result means.

What a complete tool should include

When a substantial calculator is published, the page should include:

• A clear title and short introduction
• An accessible form and immediate results
• A summary and a more detailed breakdown
• A visualization or scenario comparison when it helps
• The formula, assumptions, and limitations
• Related calculators and, when rules are involved, source links
• An educational disclaimer and a last-reviewed date

Shared methods we expect to reuse

Several upcoming tools share the same core ideas. Mortgage, auto loan, and general loan calculators typically use a standard installment-loan (amortization) payment formula. Compound interest, savings goals, and retirement estimates typically use compound-growth math. Credit card and debt-snowball tools estimate payoff time from balances, rates, and payments. Paycheck estimates are more sensitive to public tax rules; we will not invent brackets or treat a withholding estimate as a filed return.

Inputs you provide

Many results depend on values only you know: interest rates, insurance, local taxes, extra payments, or a state withholding rate. Where a national rule is not enough, the calculator should ask you for the input instead of filling in a made-up default presented as a fact.

Review

Live calculators show when the method was last reviewed. Published tools include the Mortgage Calculator, Auto Loan Calculator, and Loan Calculator. Other tools appear in the directory as coming soon until they are built.