Estimated Monthly Interest-Only Payment (at full draw):$0.00
How to Use the HELOC Calculator
A Home Equity Line of Credit (HELOC) functions like a credit card secured by your home. This calculator helps you determine how much of your home's value you can actually tap into. To get started, you need to know three key figures:
Current Home Value: What your home would likely sell for in today's market.
CLTV (Combined Loan-to-Value) Ratio: Most lenders allow you to borrow up to 80% or 85% of your home's total value, including your existing mortgage.
Mortgage Balance: The total amount you still owe on your primary mortgage.
The HELOC Formula
Lenders use a specific calculation to find your maximum credit limit. Here is the math behind this tool:
(Home Value × Max CLTV %) – Mortgage Balance = HELOC Limit
Example Calculation
Let's say your home is worth $500,000 and you owe $300,000 on your mortgage. If your lender allows an 80% CLTV:
$500,000 × 0.80 = $400,000 (Maximum total debt allowed)
Unlike standard home equity loans, HELOCs typically have variable interest rates. This means your monthly interest-only payments can fluctuate based on market conditions. During the "draw period" (usually the first 10 years), you often have the choice to pay only the interest, though paying down the principal is recommended to avoid a "payment shock" when the repayment period begins.
Pro Tip: Your credit score significantly impacts the CLTV ratio a lender will offer. A higher score (740+) often unlocks higher limits and lower interest rates.
function calculateHELOC() {
var homeValue = parseFloat(document.getElementById('homeValue').value);
var cltvLimit = parseFloat(document.getElementById('cltvLimit').value) / 100;
var mortgageBalance = parseFloat(document.getElementById('mortgageBalance').value);
var interestRate = parseFloat(document.getElementById('interestRate').value) / 100;
if (isNaN(homeValue) || isNaN(cltvLimit) || isNaN(mortgageBalance)) {
alert("Please enter valid numerical values.");
return;
}
// Calculation Logic
var maxTotalDebt = homeValue * cltvLimit;
var rawCreditLimit = maxTotalDebt – mortgageBalance;
var creditLimit = rawCreditLimit > 0 ? rawCreditLimit : 0;
var homeEquity = homeValue – mortgageBalance;
var actualCLTV = ((mortgageBalance + creditLimit) / homeValue) * 100;
// Monthly interest-only payment logic: (Limit * Annual Rate) / 12
var monthlyInt = (creditLimit * interestRate) / 12;
// Formatting Results
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
});
document.getElementById('creditLimit').innerText = formatter.format(creditLimit);
document.getElementById('totalEquity').innerText = formatter.format(homeEquity);
document.getElementById('finalCLTV').innerText = actualCLTV.toFixed(2) + "%";
document.getElementById('monthlyPayment').innerText = formatter.format(monthlyInt);
// Display result box
var resultDiv = document.getElementById('helocResult');
resultDiv.style.display = 'block';
// Smooth scroll to result
resultDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}