HELOC calculator guide
A home equity line of credit is revolving debt secured by your home. The credit limit is commonly constrained by combined loan-to-value, while the payment depends on the amount actually drawn.
Many HELOCs have variable rates and interest-only draw periods followed by higher amortizing payments.
How to use the HELOC calculator
- Enter home value and mortgage: Use current reasonable figures.
- Enter lender CLTV limit: Use the offered maximum.
- Enter planned draw and rate: Model the amount actually needed.
- Compare both phases: Review draw and repayment payments.
Formula and variables
The calculator applies the entered housing, financing, and cost assumptions consistently.
Maximum line = home value × maximum CLTV − mortgage balance- CLTV — Combined loan-to-value
- Mortgage plus HELOC balance divided by home value.
- Draw — Amount borrowed
- Balance used to estimate payments.
Worked example: payment recast
A homeowner draws $50,000 during a 10-year interest-only period.
- Rate
- 8.5%
- Estimate interest-only payment.
- Keep principal unchanged.
- Amortize balance over repayment term.
Result: The repayment payment is higher
Variable-rate increases can raise both amounts.
Understanding your results
Available line
Equity capacity at the entered CLTV cap.
Payment increase
Difference between interest-only and amortizing phases.
Assumptions
- Rate stays constant for illustration.
- No additional draws or fees.
Limitations
- Actual valuation, margins, caps, and minimum draws vary.
- Tax deductibility is not calculated.
Common mistakes
- Budgeting only for the draw payment.
- Assuming the rate is fixed.
- Borrowing the full line because it is available.
Practical use cases
Compare housing scenarios
Change one assumption at a time to identify the factors driving the result.
Plan before committing
Use estimates to prepare questions and budgets, not as a guarantee.
Planning and decision guide
Model a higher variable rate
HELOC payments can rise with the index and contract margin.
Your home secures the debt
Failure to repay can put the property at risk.
Plan before the draw period ends
The payment may jump when principal amortization begins.
Frequently asked questions
How much HELOC can I get?
It depends on value, mortgage balance, lender CLTV limits, credit, income, and underwriting.
Are HELOC rates fixed?
Many are variable, though some products offer conversion features.
Does the draw payment reduce principal?
An interest-only minimum generally does not.
Is HELOC interest tax deductible?
Eligibility depends on use and tax rules; consult current IRS guidance.
Sources and review
- What you should know about HELOCs — Consumer Financial Protection Bureau. Accessed 2026-07-10.
Reviewed 2026-07-10.