Bankrate’s Auto Loan Calculator

let stepsLog = “”; const currencySymbol = “$”, fixedCurrency = “USD”; function n(v){return isNaN(v)||v{ if(el.type===”number”||el.type===”text”) el.value=””; }); document.getElementById(“resultPayment”).value=””; document.getElementById(“resultInterest”).value=””; document.getElementById(“resultTotal”).value=””; document.getElementById(“resultTerm”).value=””; stepsLog=””; document.getElementById(“calculationSteps”).innerHTML=”

Not calculated yet.

“; } function toggleSteps(){ const s=document.getElementById(“calculationSteps”); const a=document.getElementById(“toggleArrow”); if(s.style.display===”none”||s.style.display===””){ s.style.display=”block”; a.style.transform=”rotate(180deg)”; s.innerHTML = stepsLog || “

Not calculated yet.

“; }else{ s.style.display=”none”; a.style.transform=”rotate(0deg)”; } } function calculateAutoLoan(){ stepsLog=””; const P_input = n(document.getElementById(“loanAmount”).value); const APR = n(document.getElementById(“apr”).value)/100; const y = n(document.getElementById(“termYears”).value); const m = n(document.getElementById(“termMonths”).value); const down = n(document.getElementById(“downPayment”).value); const tradeIn = n(document.getElementById(“tradeIn”).value); const taxPct = n(document.getElementById(“salesTax”).value)/100; const fees = n(document.getElementById(“fees”).value); const extra = n(document.getElementById(“extraPayment”).value); if(P_input<=0 || APR0.01 && monthCount<maxLoop){ const interest = (r===0)?0:balance*r; let principalPay = payment – interest; if(principalPaybalance){ principalPay = balance; } balance -= principalPay; totalInterest += interest; monthCount++; if(monthCount>1000 && r===0) break; } const payoffMonths = monthCount; const totalPaid = P + totalInterest; document.getElementById(“resultPayment”).value = fmt(scheduledPayment + extra); document.getElementById(“resultInterest”).value = fmt(totalInterest); document.getElementById(“resultTotal”).value = fmt(totalPaid); document.getElementById(“resultTerm”).value = `${payoffMonths} months (${(payoffMonths/12).toFixed(2)} yrs)`; stepsLog += `Inputs
Vehicle Price/Loan Amount: ${fmt(P_input)}
APR: ${(APR*100).toFixed(3)}% | Term: ${term} months
Down: ${fmt(down)} | Trade-In: ${fmt(tradeIn)} | Fees: ${fmt(fees)} | Tax: ${(taxPct*100).toFixed(2)}%
Extra Monthly: ${fmt(extra)}

`; stepsLog += `Pre-Finance Math
Taxable Base = max(0, Price − Down − Trade-In) = ${fmt(taxableBase)}
Sales Tax = Base × Tax% = ${fmt(tax)}
Financed Principal P = Base + Tax + Fees = ${fmt(P)}

`; stepsLog += `Payment Formula
For r = APR/12 and n = months:
Payment = P × r × (1+r)ⁿ / ((1+r)ⁿ − 1)${r===0?” (r=0 ⇒ Payment = P/n)”:””}

`; stepsLog += `Results
Monthly Payment: ${fmt(scheduledPayment + extra)}
Total Interest: ${fmt(totalInterest)}
Total Cost (Principal + Interest): ${fmt(totalPaid)}
Expected Payoff: ${payoffMonths} months
Tip: Even a small extra payment can shave months off the term and reduce interest substantially. `; if(document.getElementById(“calculationSteps”).style.display===”block”){ document.getElementById(“calculationSteps”).innerHTML = stepsLog; } }