HELOC Calculator

A Home Equity Line of Credit (HELOC) lets homeowners borrow against the equity they have built in their home. Unlike a fixed loan, a HELOC is a revolving credit line, closer to a credit card than to a mortgage, with a variable interest rate and a limit set by how much equity you hold.

How the credit limit is calculated: Home Equity = Current Home Value − Outstanding Mortgage Balance Maximum HELOC = (Home Value × CLTV Limit) − Mortgage Balance

The limit that matters is Combined Loan-to-Value (CLTV): your mortgage plus the new line, measured against the appraised value. Most lenders cap it at 80–85%. A few will go to 90% for borrowers with excellent credit, low debt-to-income and a well-documented income, which is why the credit tier in the calculator changes the CLTV it applies. Treat 90% as the best case a strong file might get offered, not as the norm.

Worked example:

• Home value: $420,000
• Remaining mortgage: $240,000
• Lender’s LTV limit: 85%

Maximum combined debt = $420,000 × 0.85 = $357,000 Maximum HELOC = $357,000 − $240,000 = $117,000

Monthly interest payment during draw period: Monthly Interest = (Balance × Annual Rate) / 12

On a $50,000 draw at 8.5% APR: Monthly interest = ($50,000 × 0.085) / 12 = $354.17/month

Two phases of a HELOC:

1. Draw period (typically 10 years): You borrow as needed, pay interest only
2. Repayment period (typically 10–20 years): No more draws; pay principal + interest

Key risks:

• HELOC rates are variable and tied to the prime rate, so the payment rises the moment the Fed does
• Your home is the collateral, and default can end in foreclosure
• Many HELOCs carry annual fees, inactivity fees, or early closure penalties that only appear in the fine print
• The payment shock at the end of the draw period is the one that catches people. Interest-only on $50,000 at 8.5% is $354 a month; once principal repayment starts over 15 years the same balance costs about $492 a month, and nothing about your spending changed to cause it.

HELOCs work best for ongoing, staged expenses like a renovation you pay for in phases. For a single lump sum, a fixed-rate home equity loan is usually the better instrument, because you are not exposed to rate moves for the next decade.

What the calculator does not know

It sizes the line from equity alone. Real underwriting also looks at your debt-to-income ratio, credit score, income documentation and the property type, and any one of them can shrink the number below what the equity supports. Second homes and investment properties are typically held to a lower CLTV than a primary residence. Read this as a ceiling, not as an approval.