HELOC Calculator
Estimate your maximum HELOC credit line from home value, mortgage balance, and LTV limit.
See available home equity and estimated monthly interest cost.
A Home Equity Line of Credit (HELOC) lets homeowners borrow against the equity they’ve built in their home. Unlike a fixed loan, a HELOC is a revolving credit line — similar to a credit card — with a variable interest rate and a set credit limit determined by your equity.
How the credit limit is calculated: Home Equity = Current Home Value − Outstanding Mortgage Balance Maximum HELOC = (Home Value × LTV Limit) − Mortgage Balance
Most lenders allow a combined Loan-to-Value (LTV) ratio of 80–85%, meaning total debt (mortgage + HELOC) cannot exceed 80–85% of the home’s appraised value.
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:
- Draw period (typically 10 years): You borrow as needed, pay interest only
- Repayment period (typically 10–20 years): No more draws; pay principal + interest
Key risks:
- HELOC rates are variable — tied to the prime rate — so payments rise when rates rise
- Your home is the collateral; default can result in foreclosure
- Some HELOCs have annual fees, inactivity fees, or early closure penalties
HELOCs work best for ongoing expenses like home renovations, not lump-sum needs (use a home equity loan instead for those).
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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