Loan Calculator
Monthly payment, total interest and a full amortization schedule.
Formula
About this calculator
A loan calculator turns three numbers — the amount you borrow (principal), the annual interest rate, and the loan term — into the one number you actually care about: your fixed monthly payment. It also reveals the number most lenders would rather you ignore: the total interest you will pay over the life of the loan.
The payment is derived from the standard amortizing-loan formula, where M is the monthly payment, P is the principal, r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments. Because the rate compounds monthly, a small change in the interest rate or term produces a surprisingly large change in total interest.
The amortization schedule breaks every payment into its interest and principal portions. Early payments are mostly interest; later payments are mostly principal. Seeing this split is the fastest way to understand why making even one extra payment a year can shorten a loan by months and save you real money — the extra amount goes straight to principal, so it stops accruing interest immediately.
Example: a $25,000 auto loan at 7.5% APR over 60 months costs about $501 per month and roughly $5,053 in total interest. Shortening the term to 48 months raises the payment to about $604 but cuts total interest to roughly $4,003 — you pay $103 more each month but save over $1,000 overall.
Frequently asked questions
How is my monthly loan payment calculated?
It uses the amortizing-loan formula, which spreads the principal plus compounding interest evenly across every month so your payment stays the same while the interest/principal split shifts over time.
Does paying extra actually save money?
Yes. Any amount above your required payment goes directly to principal, which reduces the balance that interest is charged on for every remaining month.
Is APR the same as interest rate?
Not always. The interest rate is the cost of borrowing the principal; APR also includes certain fees, so APR is usually slightly higher and is the better number for comparing offers.
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⚠️ Estimates are for general information only and do not include lender-specific fees, taxes or insurance. Confirm exact figures with your lender.