Loan Repayment Calculator
Calculate the monthly payment, total interest, and total cost of a fixed-rate loan.
How loan payments are calculated
Fixed-rate loans use amortization: every payment is the same amount, but the mix changes over time. Early payments are mostly interest, since the balance is largest then; later payments are mostly principal, as the balance shrinks. This calculator uses the standard amortization formula to solve for the fixed monthly payment that pays off the loan exactly over the chosen term.
The chart shows the split between principal (the amount you originally borrowed) and total interest (the extra cost of borrowing). For the same loan amount, a longer term lowers the monthly payment but increases total interest paid, because the balance stays higher for longer and accrues interest for more months.
Comparing loan offers
When comparing two loan offers, the interest rate alone doesn't tell the whole story — always compare the total interest paid, not just the monthly payment or the rate. A lower monthly payment from a longer term can end up costing significantly more overall, even at a similar or lower rate. This calculator makes that trade-off visible in one number.
This tool works for personal loans, auto loans, and other fixed-rate installment debt. For a home loan specifically — which usually involves a down payment and additional monthly costs like taxes and insurance — use the dedicated Mortgage Calculator instead. If a large loan balance is affecting your overall financial position, check the Net Worth Calculator to see the full picture.
Frequently asked questions
Does this include fees like origination charges?
No — this calculates principal and interest only, based on the loan amount, rate, and term you enter. If your loan has an origination fee, subtract it from the amount you actually receive, or add it to the loan amount if it's financed into the balance.
Why does a longer term lower my payment but cost more overall?
A longer term spreads the same principal over more payments, so each one is smaller — but the balance stays higher for longer, and interest accrues on whatever balance remains each month. More months of interest on a larger average balance adds up to a higher total cost.
Is this the same math as a mortgage?
Yes, the underlying amortization formula is identical. The Mortgage Calculator adds a few home-specific details on top — a down payment and optional monthly taxes/insurance — but the core monthly payment calculation is the same.
What if my loan has a variable interest rate?
This calculator assumes a fixed rate for the full term. For a variable-rate loan, you can still use it to estimate payments at the current rate, but re-run it whenever the rate changes to see the updated payment.