A fixed-rate loan spreads a lump sum plus interest into equal monthly payments. Understanding how the rate and term drive that payment helps you compare offers and see the true cost of borrowing.
What sets your monthly payment
Three inputs determine a fixed payment: the amount borrowed, the annual interest rate, and the term. A longer term lowers the monthly payment but increases the total interest you pay, because the balance is outstanding for longer.
The calculator uses the standard amortization formula, the same math a bank uses, so the monthly figure you see matches a typical loan statement.
The cost of a longer term
Stretching a loan from three years to six roughly halves the monthly payment, which feels like relief — but total interest can more than double. Adjust the term above and watch the total interest figure to see the trade-off directly.
A worked example
Borrow $25,000 at 6.5% over five years — that's 60 monthly payments. The payment works out to about $489, and across the full term you repay roughly $29,350, of which about $4,350 is interest.
Keep everything the same but stretch the term to seven years and the payment falls to around $373 — easier on the monthly budget, but total interest climbs to about $6,300. You'd pay nearly $2,000 more to borrow the same amount, purely for the longer runway.
Why early payments barely move the balance
With a fixed loan, every payment is the same size but its split changes. Early on, most of each payment covers interest on a large balance, so the principal barely moves; later, with little interest left to charge, almost all of it goes to principal. That's the shape you see in the amortization chart above — a balance that falls slowly at first, then faster.
It's also why paying a little extra early is so powerful: an extra $100 in month one removes principal that would otherwise have accrued interest for the entire remaining term.
Tips for comparing loan offers
Compare the APR rather than the headline interest rate — APR folds in most fees, so it's the closer measure of true cost. Watch for prepayment penalties, which can cancel out the savings from paying ahead, and be cautious with very long terms on depreciating purchases, where you can end up owing more than the item is worth.