Financial Calculators

Which financial calculator do you need?

Borrowing money. Start with the Mortgage Calculator when house hunting — it turns a home price, down payment, rate, and term into a monthly principal-and-interest payment, so you know what you can afford before you talk to a lender. The Loan Calculator does the same job for any loan: personal, student, or business. Buying a car? The Auto Loan Calculator factors in the sticker price, your down payment, and any trade-in value to estimate the monthly payment. And when you want the full picture, the Amortization Calculator lays out the year-by-year payoff schedule, showing how each payment splits between interest and principal — and how extra monthly payments can shave years off the term.

Growing money. The Compound Interest Calculator shows how savings snowball when interest earns interest, with optional monthly contributions and different compounding frequencies. The Savings Calculator is built around a goal: enter what you have, what you can deposit each month, and see when you will reach your target. The Future Value Calculator projects a lump sum forward — handy for asking "what will this investment be worth in 20 years?"

Comparing and solving. Money today is worth more than the same money later, and the Present Value Calculator discounts a future sum back to today's dollars so you can compare offers fairly. The ROI Calculator expresses any gain as a percentage of cost, the standard way to compare investments of different sizes. And the Interest Rate Calculator works backward: given where you are and where you want to be, it solves for the annual rate you need.

The core formulas behind these tools

Every tool here is built on a small set of transparent formulas. Loan payments use the amortization formula: monthly payment = P·r(1+r)^n / ((1+r)^n − 1), where P is the loan amount, r the monthly rate, and n the number of payments. That is why a $300,000 loan at 6.5% for 30 years costs $1,896.20 a month — most of the early payments go to interest, not principal. Compound growth uses A = P(1+r/n)^(nt): $10,000 at 7% compounded monthly for 10 years becomes $20,096.61, more than double, because each month's interest starts earning its own interest. Present and future value are two sides of one coin: FV = PV(1+r)^n going forward, PV = FV/(1+r)^n going back — so $100,000 ten years from now at 6% is worth only $55,839.48 today. And ROI is the simplest of all: (gain − cost) ÷ cost, expressed as a percent. Knowing these lets you sanity-check any result in seconds.

Tips for better numbers

Compare APR, not just the interest rate, when shopping for loans — APR folds in most fees and is the truer cost. Run the same scenario at two or three different rates; even half a percentage point moves a 30-year mortgage by tens of thousands of dollars. For savings, the boring truth is that time and regular contributions beat clever timing — start with what you can and let compounding do the heavy lifting. Double-check anything these tools tell you against your lender's or advisor's figures before signing, since real loans include taxes, insurance, and fees these estimates do not model. And keep perspective: these calculators are planning aids, not financial advice.