Compare from today, not from the purchase date
Enter today's outstanding principal and the payments remaining. Already-paid interest is excluded because both choices start now. The new loan refinances exactly that principal. Include origination charges and any early-settlement penalty in upfront fees; this version does not add those fees to the new loan balance.
The headline saving is the old remaining payments minus all new payments and upfront fees. A negative number means refinancing costs more over the full chosen term. Extending the term can reduce the monthly payment while raising total future spending.
Why the lender's quote can differ
Both loans are fixed-rate, fully amortizing and paid monthly, without a balloon or missed payments. Daily interest, settlement-date interest, fees financed into the loan and contract rounding require the lender's payoff quote. Interest inputs are nominal annual rates, not fee-inclusive APR estimates. The CFPB's loan comparison guidance also distinguishes the rate, term and amount financed. The result is a comparison, not credit approval.
Keep the term unchanged first to isolate the interest-rate effect. Then test a different term and inspect the total. Use the balloon calculator if a final lump sum is part of your contract, or extra payments to explore repaying faster without refinancing.