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Loan Calculator
Enter a loan amount, annual interest rate, and term. The monthly payment, total interest, total cost, and payoff date update instantly, with a year-by-year amortization table and an optional extra monthly payment to see how fast it shortens the loan. Estimates only: they exclude fees, taxes, insurance, and variable-rate changes.
How it works
An amortizing loan is paid off in equal monthly payments that cover that month’s interest first, with the rest reducing the balance — so early payments are mostly interest and later ones mostly principal. The monthly payment is M = P · i(1+i)n / ((1+i)n − 1), where P is the amount borrowed, i the monthly rate (annual rate ÷ 12), and n the number of payments. Worked example: $200,000 at 6% over 30 years (360 payments): i = 0.005, so M = 200,000 × 0.005 × 1.005360 / (1.005360 − 1) = $1,199.10/month. Over the full term you pay $431,676.38 total, of which $231,676.38 is interest — more than the amount borrowed. Adding $200/month extra cuts the term to 21 years (252 payments) and saves $79,800.51 in interest (exact figures update live above). The payoff date counts forward from today.
Frequently asked questions
Why is so much of my early payment interest?
Interest is charged on the current balance. With a large balance early on, most of the fixed payment is eaten by interest; as the balance falls, the same payment covers more principal. That is why extra payments early in a loan save the most.
Does an extra payment really save that much?
Yes — extra money goes straight to principal, which shrinks every future interest charge. On the worked example, $200/month extra saves $79,800.51 and 9 years (360 → 252 payments). The calculator shows your exact saving for any extra amount.
What is not included?
Fees, closing costs, taxes, insurance (escrow), PMI, and any rate changes on adjustable loans. For a mortgage, the true monthly outlay is usually higher than the principal-and-interest figure here — see the mortgage calculator for the full picture.
What if the rate is 0%?
Then the payment is simply the amount divided by the number of payments: $200,000 over 360 months = $555.56/month, with no interest at all.
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