Loan Repayment Extra Payment Calculator

let repaymentSteps = “”; const currencySymbol = “$”, fixedCurrency = “USD”; function calculateLoanRepayment() { repaymentSteps = “”; const loanAmount = parseFloat(document.getElementById(“loanAmount”).value); const interestRate = parseFloat(document.getElementById(“interestRate”).value) / 100 / 12; const loanTerm = parseFloat(document.getElementById(“loanTerm”).value) * 12; const extraPayment = parseFloat(document.getElementById(“extraPayment”).value); if (isNaN(loanAmount) || isNaN(interestRate) || isNaN(loanTerm) || isNaN(extraPayment) || loanAmount <= 0 || interestRate <= 0 || loanTerm <= 0) { alert("Please enter valid positive values for all fields."); return; } const monthlyPayment = (loanAmount * interestRate) / (1 – Math.pow(1 + interestRate, -loanTerm)); const newLoanAmount = loanAmount – extraPayment; const totalInterest = (monthlyPayment * loanTerm) – loanAmount; document.getElementById("monthlyPayment").value = formatCurrency(monthlyPayment); document.getElementById("totalInterest").value = formatCurrency(totalInterest); repaymentSteps += `Inputs:
Loan Amount: ${formatCurrency(loanAmount)}
Interest Rate: ${(interestRate * 100).toFixed(2)}%
Loan Term: ${loanTerm / 12} years
Extra Payment: ${formatCurrency(extraPayment)}

`; repaymentSteps += `Formulas:
Monthly Payment = (Loan Amount × Interest Rate) ÷ (1 – (1 + Interest Rate)^(-Loan Term))
Total Interest = (Monthly Payment × Loan Term) – Loan Amount

`; repaymentSteps += `Results:
Monthly Payment: ${formatCurrency(monthlyPayment)}
Total Interest Paid: ${formatCurrency(totalInterest)}
`; repaymentSteps += `Tip: Extra payments reduce the amount of interest paid and shorten the loan term. Consider making extra payments if you want to pay off your loan faster.`; if (document.getElementById(“calculationStepsRepayment”).style.display === “block”) { document.getElementById(“calculationStepsRepayment”).innerHTML = repaymentSteps; } } function resetLoanRepayment() { document.querySelectorAll(“#loanRepaymentCalculator input”).forEach(el => el.value = “”); repaymentSteps = “”; document.getElementById(“calculationStepsRepayment”).innerHTML = “

Not calculated yet.

“; } function toggleLoanRepaymentSteps() { const s = document.getElementById(“calculationStepsRepayment”); const a = document.getElementById(“toggleArrowRepayment”); if (s.style.display === “none” || s.style.display === “”) { s.style.display = “block”; a.style.transform = “rotate(180deg)”; s.innerHTML = repaymentSteps || “

Not calculated yet.

“; } else { s.style.display = “none”; a.style.transform = “rotate(0deg)”; } } function formatCurrency(n) { return currencySymbol + n.toFixed(2) + ” ” + fixedCurrency; }