The payment formula
Monthly payment = P × i / (1 − (1 + i)^−n), where P is the amount borrowed, i is the monthly interest rate (the annual rate divided by 12) and n is the number of months in the term. Because interest is charged on the outstanding balance, every payment is mostly interest in the early months and gradually shifts toward principal.
Total interest is the monthly payment multiplied by the number of payments, minus the amount borrowed. That single figure is where short and long terms differ most, and it is the number the schedule makes easy to see rather than hide.
Why the term matters more than the rate
Stretching a loan over more months lowers the payment but raises the total interest, because the balance stays outstanding for longer. On a $25,000 loan at 8%, a 5-year term costs roughly $5,400 in interest while a 7-year term costs around $7,700.
The rate still matters, so if you are comparing offers, compare the APR rather than the headline rate: fees change the effective cost and the APR calculator shows that difference. Each result is pinned to the inputs you type, so the trade between a smaller payment and a smaller total cost is spelled out in dollars.
What this tool does not include
There are no origination fees, late charges or insurance products in the model, and the rate is treated as fixed for the whole term. Variable-rate loans need a payment for each rate scenario instead, because a changing rate changes every later payment.
Payments are monthly and interest is charged monthly on the outstanding balance, which matches how most consumer loans are documented in the United States, Canada, the UK and Australia. The schedule runs from the start month you choose, so the rows line up with the real calendar of the loan.
Using the schedule to test a payoff plan
The schedule column nearest the back of the loan is the one that responds to extra payments. Paying a little extra principal each month shortens the term from the end and cuts the total-interest figure; the amortization and payoff calculators run the same loan with the extra built in.
The point of the schedule is that the trade is explicit: any plan that changes the payment or the term shows its effect as a different total, instead of a hand-waved claim that paying more is better. Compare a few scenarios side by side before you commit extra cash to the loan.
The four numbers a lender quotes, and the one that decides
Every offer arrives with four numbers: the amount, the rate, the term and the monthly payment. Only one of them is a decision — the payment you can still make in a bad month — and the other three exist to move it. A lender can lower the payment by stretching the term or by raising the amount, and both moves raise the total cost, so a lower payment is not automatically a better loan. This page prints the payment and the total side by side for exactly that reason: the pair is the decision, not either number on its own. A shorter term whose payment you can still survive in a bad month is, almost every time, the cheaper loan.
The classic trap is comparing two offers by rate. A $25,000 loan at 8% over five years costs about $5,400 in interest; the same $25,000 at 7.25% over seven years costs more than $6,700 even though the rate is lower, because the balance stays alive for 24 more months. Read the interest per $100 borrowed in the results — it puts both offers on one scale — then look at what the first payment is made of: at 8% over five years, roughly $167 of the first $507 is interest, and by the final year almost all of it is principal. That is also why the term is the lever a lender reaches for first: extending it lowers the payment without changing a single number in the rate column.
Danfio