HELOC Calculator
Estimate your maximum home equity line of credit from your LTV, plus interest-only draw payments and full repayment payments.
Enter your home value, mortgage balance, and the lender's maximum loan-to-value ratio to find your available credit line. Then model a draw amount across a draw period with interest-only payments and a repayment period with fully amortizing payments, so you see the true cost of borrowing against your equity.
How to use this calculator
- Enter your current home value and remaining mortgage balance.
- Set the lender's maximum LTV (80% is typical) to find your available credit line.
- Enter the amount you plan to draw, the interest rate, and the draw and repayment periods.
- Click Calculate to see interest-only draw payments and amortizing repayment payments.
- Compare the payment jump between phases before committing.
The formula
Max line = (home value × max LTV%) − mortgage balance; interest-only payment = drawn balance × monthly rate.
Worked example
A $500,000 home with a $300,000 mortgage at an 80% LTV cap supports a $100,000 line. Drawing $50,000 at 8% costs $333.33 per month interest-only during a 10-year draw period, then $418.22 per month over a 20-year repayment period.
Frequently Asked Questions
How is my HELOC credit limit calculated?
Most lenders cap the combined loan-to-value (CLTV) at 80%, meaning your mortgage balance plus your HELOC line cannot exceed 80% of the home's value. Your maximum line is 80% of the home value minus your current mortgage balance. Some lenders allow up to 85-90% CLTV, usually at higher rates.
What happens during the draw period versus the repayment period?
During the draw period, typically 10 years, you can borrow against the line and usually make interest-only payments on what you have drawn. Once the draw period ends, the repayment period begins, typically 15-20 years, during which you can no longer draw and must make fully amortizing principal-and-interest payments. Payments often jump substantially at that transition.
Is HELOC interest tax deductible?
HELOC interest may be deductible if the borrowed funds are used to buy, build, or substantially improve the home securing the loan, subject to IRS limits on mortgage debt. Interest on funds used for other purposes, like paying off credit cards or buying a car, is generally not deductible. Tax rules change, so confirm with a tax professional.
HELOC vs home equity loan: which is better?
A HELOC is a revolving line with a variable rate, ideal when you need flexibility or will borrow in stages, such as a phased renovation. A home equity loan gives a lump sum at a fixed rate with predictable payments, better for a single known expense. Compare the rate risk of the HELOC against the certainty of the fixed loan.
What are the risks of a HELOC?
Your home secures the debt, so missed payments can lead to foreclosure. Variable rates mean payments can rise, and the payment shock when the interest-only draw period ends catches many borrowers off guard. Borrow only what you need, have a plan for the repayment phase, and keep an emergency buffer.