Estimate your monthly payments for both the Draw and Repayment periods.
Estimated Monthly Payments
Draw Period (Interest-Only):$0.00
Repayment Period (Principal + Interest):$0.00
Total Interest Paid (Repayment Phase):$0.00
Understanding Your HELOC Payments
A Home Equity Line of Credit (HELOC) is a unique financial tool that functions differently than a standard home equity loan. It typically consists of two distinct phases: the Draw Period and the Repayment Period. This calculator helps you navigate the transition between these two phases so you aren't caught off guard by "payment shock."
The Draw Period vs. Repayment Period
During the Draw Period (usually the first 10 years), you can borrow as needed up to your credit limit. Most HELOCs only require interest-only payments during this time. While this keeps monthly costs low, it means you aren't making progress on paying down the debt.
Once the Repayment Period begins (usually years 11–30), you can no longer withdraw funds. Your monthly payment will increase significantly because you must now pay back both the principal balance and the interest over the remaining term.
HELOC Calculation Example
Imagine you have a $50,000 balance on a HELOC with an 8.5% interest rate:
During Draw Period: Your monthly interest-only payment would be approximately $354.17 ($50,000 * 0.085 / 12).
During Repayment Period: If you have a 20-year repayment term, your payment would jump to approximately $433.91 per month to fully amortize the loan.
Factors That Affect Your HELOC Payment
Variable Interest Rates: Most HELOCs have variable rates tied to the Prime Rate. If market rates go up, your monthly payment will increase.
The Prime Rate: As the Federal Reserve adjusts rates, your HELOC cost will likely mirror those changes within one or two billing cycles.
Balloon Payments: Some HELOCs require the entire balance to be paid in full at the end of the draw period. Always check your loan agreement for balloon payment clauses.
How to Lower Your HELOC Costs
To avoid a massive increase in payments when the repayment period starts, consider making "Principal + Interest" payments even during the draw period. This reduces your total balance and minimizes the total interest paid over the life of the credit line.
function calculateHELOC() {
var balance = parseFloat(document.getElementById("helocBalance").value);
var annualRate = parseFloat(document.getElementById("helocRate").value);
var drawYears = parseFloat(document.getElementById("drawPeriod").value);
var repayYears = parseFloat(document.getElementById("repayPeriod").value);
if (isNaN(balance) || isNaN(annualRate) || isNaN(repayYears) || balance <= 0 || annualRate < 0 || repayYears <= 0) {
alert("Please enter valid positive numbers for balance, rate, and repayment years.");
return;
}
var monthlyRate = (annualRate / 100) / 12;
// 1. Interest Only Payment (Draw Period)
var interestOnlyPayment = balance * monthlyRate;
// 2. Principal + Interest Payment (Repayment Period)
// Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var totalMonthsRepay = repayYears * 12;
var repaymentPayment = 0;
if (monthlyRate === 0) {
repaymentPayment = balance / totalMonthsRepay;
} else {
var x = Math.pow(1 + monthlyRate, totalMonthsRepay);
repaymentPayment = (balance * x * monthlyRate) / (x – 1);
}
// 3. Total Interest in Repayment Phase
var totalInterestRepay = (repaymentPayment * totalMonthsRepay) – balance;
// Format results
document.getElementById("interestOnlyResult").innerText = "$" + interestOnlyPayment.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById("repaymentResult").innerText = "$" + repaymentPayment.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById("totalInterestResult").innerText = "$" + totalInterestRepay.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
// Show results section
document.getElementById("helocResults").style.display = "block";
}