Home Equity Line of Credit Calculator
See how much equity you can tap, what your draw-phase payments will be, and — critically — how much your payment jumps at repayment.
About this tool
A HELOC gives you flexible access to your home equity, but its two-phase structure (interest-only draw, then full P&I repayment) means payments can jump significantly. This calculator shows the full picture.
How to use it
Quick steps to get the most out of this utility.
- 1
Enter your home details
Home value, existing mortgage balance, and lender CLTV cap.
- 2
Set HELOC terms
Interest rate, draw period length, and repayment period length.
- 3
Specify your draw plan
How much you intend to borrow and when.
- 4
See the full payment timeline
Draw-phase payments, repayment-phase payments, and total interest cost.
HELOC Credit Limit: How Lenders Calculate What You Can Borrow
Your maximum HELOC amount is determined by your Combined Loan-to-Value ratio. Most lenders cap at 80-85% CLTV. Subtract your existing mortgage from that maximum combined loan amount, and you have your credit limit. This calculator enforces the cap — you cannot model borrowing more than the lender will allow.
The Two-Phase Payment Structure
During the draw period (typically 10 years), you pay interest only on what you've borrowed. Payments are low and flexible — if you pay down principal, you free up credit again. When the draw period ends, your HELOC closes to new draws and converts to a full amortizing loan. The 'payment shock' — the jump from interest-only to P&I — is often 25-50% higher than what you were paying. Knowing this number in advance lets you plan ahead.
Frequently asked questions
What is CLTV and why does it matter?+
Combined Loan-to-Value (CLTV) is the ratio of all loans on your home to its appraised value. Lenders cap CLTV at 80-90% for HELOCs. If your home is worth $500k and your mortgage is $250k, an 85% CLTV cap means your maximum HELOC is $175k.
What happens to my HELOC if my home value drops?+
Lenders can reduce or freeze your HELOC if your home value drops significantly, your credit score declines, or the lender experiences financial stress. This is a key risk of HELOCs vs. home equity loans.
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