HELOC Calculator
Created by: Emma Collins
Last updated:
Calculate your HELOC credit limit based on combined LTV, your draw-period interest-only payment, and the higher amortizing payment that begins at repayment — so you can plan for the payment increase before signing.
HELOC Calculator
FinanceCalculate your HELOC credit limit from combined LTV, then see the draw-period interest-only payment and the repayment-period amortizing payment — and plan for the payment increase.
What Is a HELOC?
A home equity line of credit (HELOC) lets you borrow against your home's equity as needed, up to a pre-approved limit.
It is structured in two phases: a draw period (typically 10 years) during which you can borrow and repay interest only, followed by a repayment period (typically 20 years) during which the outstanding balance amortizes fully.
HELOCs are popular for home improvement, debt consolidation, and education expenses because they provide flexible, low-cost access to capital secured by your largest asset.
But the variable rate and deferred principal repayment create real risks that require careful planning.
How HELOC Payments Are Calculated
Your credit limit is determined by your home's combined LTV — typically 80–85% of appraised value minus the outstanding first mortgage.
During the draw period, interest-only payment = balance × (draw rate / 12).
During the repayment period, the outstanding balance amortizes using the standard mortgage payment formula.
HELOC Payment Formulas
Credit limit = home value × combined LTV% − outstanding mortgage
Draw period payment (interest only) = balance × (annual rate / 12)
Repayment period payment = balance × r(1+r)^n / ((1+r)^n − 1)
Example Scenarios
Home Renovation Project
Home value: $450,000. Mortgage: $280,000. HELOC limit: $450,000 × 85% − $280,000 = $102,500. Draw: $60,000 at 8.5%. Draw period payment: $425/month. After 10 years, $60,000 repaid at 9% over 20 years: $540/month. Total interest: ~$61,000.
Debt Consolidation Use Case
HELOC draw: $25,000 at 7.5% to pay off $25,000 at 22% credit card debt. Monthly payment on HELOC draw period: $156 vs. $555 minimum on the card. Monthly savings: ~$400. Important caveat: the HELOC is secured by your home — the credit card is not.
How People Use This Calculator
- Homeowners planning multi-phase renovation projects who want to draw funds in stages.
- Parents using a HELOC as a flexible tuition payment source over 4 years.
- Homeowners evaluating HELOC vs home equity loan for a large one-time expense.
- Anyone modeling what happens to their HELOC payment if interest rates rise by 1–2%.
- Financial planners stress-testing HELOC costs for clients in retirement.
Tips for HELOC Planning
Don't borrow to your limit just because you can.
Lenders approve your credit limit based on maximum scenarios; your actual draw should match your actual needs.
Unused credit does not accrue interest, but it does count against your combined LTV if you try to refinance.
Always model the repayment-period payment before signing.
Many borrowers focus only on the low draw-period payment, then experience sticker shock when principal repayment begins.
If the repayment payment would strain your budget, reduce the draw amount now.
Frequently Asked Questions
What is a HELOC?
A HELOC (home equity line of credit) is a revolving credit line secured by your home's equity. Unlike a home equity loan that gives you a lump sum, a HELOC works like a credit card — you borrow as needed up to your limit during the draw period, paying interest only on what you use. After the draw period ends, you repay the principal plus interest over the repayment period.
How is a HELOC credit limit calculated?
Lenders typically allow a combined LTV (loan-to-value) of up to 85% of your home's appraised value. Your HELOC limit equals 85% of home value minus your outstanding mortgage balance. For a $400,000 home with a $250,000 mortgage: limit = $400,000 × 85% − $250,000 = $340,000 − $250,000 = $90,000.
What is the draw period?
The draw period is typically 5–10 years during which you can borrow from and repay the HELOC. During this time, most HELOCs require interest-only payments on your outstanding balance. Your rate is usually variable, tied to the prime rate plus a margin, so payments fluctuate with rates.
What happens after the draw period?
After the draw period ends, the HELOC enters its repayment period (usually 10–20 years). The line closes — no more borrowing — and any outstanding balance is amortized over the repayment term. Monthly payments increase significantly because they now include principal. Plan for this "payment shock" in your budget.
Is a HELOC better than a home equity loan?
It depends on how you plan to use the funds. HELOCs are better for ongoing or irregular expenses (home renovations over several years, tuition) where you draw as needed. Home equity loans are better for lump-sum, one-time expenses where a fixed rate and payment provide predictability. HELOCs typically start with lower payments but carry rate risk.
What is the risk of a HELOC?
The primary risks are: (1) rate risk — a variable rate can rise substantially, as many homeowners learned in 2022–2023, dramatically increasing draw period payments; (2) payment shock when repayment begins; and (3) the risk of overborrowing against your home, which is secured collateral. Missing payments can ultimately lead to foreclosure.
Sources and References
- Consumer Financial Protection Bureau (CFPB). Home Equity Loans and HELOCs. consumerfinance.gov.
- Federal Reserve Board. What You Should Know About Home Equity Lines of Credit.
- Freddie Mac. Home Equity Line of Credit Basics. freddiemac.com.