HELOC calculator: estimate your line size and payments
To calculate your maximum HELOC line, take 85 percent of your home value, subtract your existing mortgage balance, and round to the nearest $1,000. That is your available equity at the program’s standard combined loan-to-value cap.
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How the calculator works
The calculator uses two inputs: your estimated home value and your current first mortgage balance.
The math is straightforward. For a primary residence, multiply your home value by 0.85 (the 85 percent CLTV cap). Subtract your first mortgage balance. The result is the estimated maximum HELOC line.
(Home value × 0.85) − first mortgage balance = available HELOC line (primary residence).
For investment property, replace 0.85 with 0.70.
Want the full mechanics behind the cap? See HELOC qualification.
What the calculator includes and what it does not
The calculator gives you a quick estimate of line size. It does not give you a rate quote, exact monthly payment, or final approval.
Includes: estimated line size at the standard CLTV cap.
Does not include: your specific rate, exact payment, qualification confirmation, property value confirmation, or income verification. Those require an actual application.
The next step after the calculator is a soft credit check. The pull returns your real rate, confirms eligibility, and validates the line size estimate against actual underwriting. No impact on your credit score. For definitions of CLTV, AVM, draw fee, and other technical terms used on this page, see the HELOC glossary.
How HELOC payments are calculated
Payment is based on your outstanding balance, not your line size.
During the draw period, payments are typically interest-only. The interest charge is your balance times your current rate, divided by 12. As your balance changes, your payment changes.
When the line enters repayment, the payment recalculates to include principal. It is now sized to pay off the remaining balance over the rest of the term.
Payment estimates are harder than line size estimates because the rate is borrower-specific. Your actual rate depends on your credit, line size, occupancy type, and the draw fee you select. For the full picture, see how HELOC rates work and how a HELOC works.
Common calculator scenarios
Three borrower scenarios anchored in real numbers. Each runs the formula end to end.
Home value $500,000. First mortgage $300,000.
$500,000 × 0.85 = $425,000 total allowed debt.
$425,000 − $300,000 = $125,000 available HELOC line.
Home value $750,000. First mortgage $100,000.
$750,000 × 0.85 = $637,500 total allowed debt.
$637,500 − $100,000 = $537,500 available equity, capped at $400,000 (current maximum line).
Home value $1,200,000. First mortgage $400,000.
$1,200,000 × 0.85 = $1,020,000 total allowed debt.
$1,020,000 − $400,000 = $620,000 available equity, capped at $400,000 (current maximum line).
Note: Lines above $400,000 are handled outside the standard digital program. We offer other HELOC programs above $400,000. Start with the form.
Like your number? See your real rate next.
A soft credit check returns your actual HELOC rate in minutes. No commitment to proceed.
No impact on your credit score to find out.
What to do with your estimate
Your calculator result puts you in one of three buckets.
Estimate above $25,000 and below $400,000. You are in the standard digital HELOC range. Start the soft credit check to get your real rate. See how to apply for a HELOC for the full step-by-step.
Estimate below $25,000. Available equity is too small for the current digital program. Options include waiting for home values to rise, paying down the first mortgage, or talking with a loan officer about other product paths.
Estimate above $400,000. We offer other HELOC programs above $400,000. Start with the form below.
Before drawing on any HELOC, understand the trade-offs. See HELOC risks and disclosures for the full risk framework. The HELOC sits in second position behind your first mortgage, so it preserves your low first mortgage rate. See keep your low mortgage rate for that framework.
When your estimate may differ from your actual approval
The calculator uses the numbers you enter. Actual approval uses the lender’s confirmed numbers. Four common reasons your estimate may differ from your approval:
- Property value. The lender uses an automated valuation (AVM) in most cases. The AVM value may differ from your estimate.
- Credit profile. Your FICO score affects pricing and, in edge cases, approval itself.
- Income and DTI. Verifiable income that supports the new payment is required. High DTI can reduce the approved line.
- State-specific overlays. Some states have additional underwriting requirements that affect the final approved line.
The calculator gets you in the ballpark. The application confirms the actual number. For the full underwriting rules, see HELOC qualification and HELOC rates, fees, and closing costs.
HELOC calculator, answered
Why does the calculator use 85 percent and not 100 percent of my home value?
Because 85 percent is the current combined loan-to-value cap for primary residences on the digital HELOC. The lender requires a 15 percent equity buffer to manage risk. Investment properties cap at 70 percent.
Is the calculator estimate the same as a pre-approval?
No. The calculator is a quick estimate based on equity math alone. Pre-approval requires a soft credit check, income verification, and full property review. The calculator tells you if you are in the ballpark. Pre-approval tells you for certain.
Can I trust the home value I entered?
The calculator uses whatever value you enter. For a more accurate estimate, use a recent appraisal value, a comparable home sale price, or a Zillow/Redfin estimate. The actual approval will use an automated valuation (AVM) or formal appraisal, which may differ from your estimate.
Why does the calculator not show me my exact monthly payment?
The actual payment depends on multiple variables we do not have yet: your credit-determined rate, your draw fee selection, your term length choice, and the current index value. The calculator shows your maximum line size, which is the variable most borrowers want first.
What if the calculator says I have negative equity available?
That means your existing mortgage balance exceeds 85 percent of your current home value. A HELOC is not possible at this point. Options include waiting for home values to rise, paying down the first mortgage, or considering other products. Talk with a loan officer about your situation.
The calculator says I qualify for more than $400,000. What now?
Lines above $400,000 are handled outside the standard digital program. We offer other HELOC programs above $400,000. Start with the form below to talk with a loan officer about your options.
See your real rate next
Soft credit check. Real numbers.
No impact on your credit score to find out.