Auto loan calculator plus estimate your monthly car loan payment Shopping for the right auto loan before you visit the car lot can save you money. Use our auto loan calculator to estimate monthly payments and find the lowest rates available. That way, you can find the vehicle that fits your budget and negotiate the best deal. Enter a total loan amount into this auto loan calculator to estimate your monthly payment, or determine your loan amount by car price, trade-in value and other factors. Adjust the loan term, down payment amount and interest rate to see results based on the numbers you provide – and how any changes to those numbers may affect your payment. *This is a universal app that work for both iPhone and iPad.