Auto Loan Trade–In Equity Calculator
Determines auto loan trade-in equity from relevant inputs and returns a dedicated result for borrowing and repayment planning.
Input Parameters
Includes $4,000.00 positive equity applied
Analytical Summary
Mathematical Formula & Methodology
Underlying equations and mathematical logic governing this engine
Net Trade-In Equity (E_net)
E_net = V_trade - B_loanDifference between dealer trade-in market value and current loan payoff balance. Positive reduces loan; negative rolls debt.
Taxable Base Price (P_taxable)
P_taxable = max(0, P_new - V_trade)In most states, sales tax is assessed solely on difference between new vehicle purchase price and trade value.
Net Sales Tax Liability (T_net)
T_net = P_taxable * (Tax_rate / 100)Actual state sales tax owed after applying dealer trade-in tax credit.
Tax Dollars Saved via Credit (T_saved)
T_saved = min(P_new, V_trade) * (Tax_rate / 100)Direct sales tax dollars saved compared to purchasing without a trade-in credit.
Final Net Financed Principal (P_financed)
P_financed = (P_new + T_net) - E_net - D_cashTotal loan principal required to finance the purchase after factoring net equity, taxes, and down payment.
How to Use This Calculator
Enter Dealer Trade-In Market Value
Obtain current wholesale trade appraisal or fair market trade value quote.
Input Exact Auto Loan Payoff
Obtain official 10-day payoff balance from current auto lender.
Specify New Vehicle MSRP / Price
Input negotiated out-the-door vehicle price before local government taxes.
Apply Sales Tax & Cash Down
Set state tax rate and cash down payment to view exact financed principal.