Loan Calculator
Monthly payment and total interest for any fixed-rate loan — car, personal, student, or mortgage — with a year-by-year amortization table so you can see where the money goes.
Loan terms
First rows of the table show how early payments skew toward interest — that's amortization, not a lender trick, but it's why extra early payments are so powerful.
The formula, in plain terms
Fixed-rate loans use the standard amortization formula: payment = P × r ÷ (1 − (1 + r)−n), where P is the amount borrowed, r is the monthly rate (APR ÷ 12), and n is the number of monthly payments. The formula finds the one constant payment that exactly zeroes the balance on the last month, with each payment first covering that month's interest and the remainder reducing principal.
That structure has a consequence worth internalizing: early payments are mostly interest, late payments are mostly principal. On a 30-year mortgage the crossover — the month principal finally exceeds interest in your payment — can arrive past year 15. It isn't a trick; interest is simply charged on the balance, and the balance is biggest at the start. But it's why extra payments made early in a loan's life eliminate far more interest than the same dollars paid late.
Worked example
A $25,000 car loan at 8.5% for 5 years: the payment comes to about $513, and total interest to roughly $5,770 — the car really costs about $30,770. Stretch the same loan to 7 years and the payment drops to about $396, which sounds better until you see total interest climb past $8,200. The monthly payment measures affordability; total interest measures cost. Dealers negotiate on the first number for a reason.
Reading the amortization table
The year-by-year table shows three things worth checking before signing anything: how much interest the first year alone costs (this is what refinancing or early payoff saves you the most of), the year your balance falls below any threshold that matters to you (like 80% of a home's value, where PMI can be removed), and the total trajectory — a sanity check that the loan actually terminates when promised. For mortgage-specific decisions, the refinance calculator compares two loans head-to-head, and home affordability works the problem backwards from income to loan size.
Questions people ask
APR vs. interest rate — which do I enter?
APR, if you have it. APR folds mandatory fees into the rate, making it the more honest number and the right one for comparing offers. Note that for credit cards, "APR" works differently (interest compounds on daily balances) — for cards, use the debt payoff calculator instead.
How much do extra payments help?
On the example above, an extra $100/month pays the car off about 11 months early and saves around $1,100 in interest. The earlier in the term extra money arrives, the more it saves — see the minimum payment trap for the extreme version of this logic in reverse.
Why doesn't my lender's quote match exactly?
Real loans have funding-date quirks, odd first periods, and fees paid at closing rather than financed. Differences of a few dollars are normal; differences of $50+ mean the quote includes something you haven't been told about — ask.