Complete Auto Calculator

No. Loan amount is floored at zero -- if your trade-in credit plus down payment would otherwise exceed the vehicle price plus sales tax, the calculator shows a $0 loan rather than a negative figure. It does not calculate or display any cash-back amount you might be owed beyond that point; it only models the financed portion.

No. Each of the five modes (buy, lease, total cost of ownership, road trip, EV comparison) computes entirely independent formulas from its own relevant inputs -- values you enter for one mode, like trip distance, have zero effect on another mode's outputs, like loan amount, even though they all live in the same calculator.

Vehicle price is the largest single term in the loan-amount formula (vehicle price plus sales tax, minus down payment and trade-in) and also carries this calculator's widest declared range, from $5,000 to $200,000. Both together make it move the loan amount more, in absolute terms, than any other single input in buy mode.

Yes, in this calculator's model, holding interest rate and loan amount fixed -- stretching payments over more months means more time for interest to accrue against the outstanding balance, even though it simultaneously lowers the monthly payment. That tradeoff between lower payments and higher total interest is inherent to amortized loans, not specific to this calculator.

Treat it as an approximation. This calculator applies sales tax to vehicle price after subtracting trade-in value, which matches how many US states structure trade-in tax credits -- but several states tax the full vehicle price regardless of trade-in, and rates and rules vary significantly by state and even by county, so verify against your local DMV or dealer figures before relying on this number.