Car Refinance Calculator - Auto Loan Savings

The car refinance calculator compares an existing auto loan with a proposed refinance. It estimates the current remaining payment, the new payment, monthly savings, total interest savings, and break-even months after refinance fees. This is useful when rates fall, credit improves, a borrower wants a shorter payoff path, or a lower payment is needed for cash-flow reasons. The calculation amortizes the current balance over the remaining term at the current APR, then amortizes the balance plus refinance fees over the new term at the new APR. The formula is: monthly savings = current amortized payment - new amortized payment on balance plus fees; interest savings = remaining current interest - new interest including refinance fees. Break-even months divide upfront refinance fees by monthly savings when savings are positive. Use the calculator to distinguish payment relief from true savings. A refinance can lower the monthly payment by extending the term even when total interest rises. Conversely, a shorter term at a lower APR may save interest but increase the monthly payment. The result card shows both monthly and total-interest effects so users can choose based on budget and payoff goals rather than the payment alone. The estimate assumes fixed-rate amortizing loans and does not include title fees, prepayment penalties, lender-specific add-ons, credit score changes, or vehicle value constraints unless entered as refinance fees. Before refinancing, compare the output with the lender quote, verify that the car is eligible, and check whether extending the loan could increase negative equity risk. For best results, keep all inputs on the same time basis and currency basis, then save the assumptions beside the output. That practice makes the estimate easier to audit later and prevents a common spreadsheet error: mixing monthly values with annual values or combining before-tax and after-tax figures. Re-run the scenario with conservative and optimistic assumptions before using the result in a budget, filing decision, trade review, or transaction memo.