Free Car Payment with Trade In calculator with clear step-by-step results.
The number that matters on a trade-in is net equity, not the appraisal. Subtracting the outstanding loan from the appraised value can leave a negative figure, which then gets added to the new loan rather than reducing it - this calculator handles that case explicitly.
Net equity
Equity = trade-in appraisal - remaining loan payoff
Monthly payment
Payment = financed amount x r / (1 - (1 + r)^-n)
The negative equity rolls into the new loan, so the amount financed exceeds the vehicle price. The calculator shows negative net equity and a correspondingly larger financed amount.
Negotiate them separately. Dealers can quietly move value between the two and still hit the payment you asked for while making more on the deal.