HELOC Calculator

How Does a HELOC Work?

A HELOC (Home Equity Line of Credit) provides revolving access to your home equity, similar to a credit card secured by your property. Enter the credit line amount, drawn balance, interest rate, and repayment term in the calculator above. It shows the available credit remaining, the interest-only payment during the draw period, and the fully amortized payment during the repayment period. HELOCs offer flexible borrowing against equity you have built, but the variable rate and payment structure require careful management.

HELOC Structure: Draw Period and Repayment Period

Most HELOCs have two phases. Draw period (typically 5-10 years): borrow and repay freely up to the credit limit. Minimum payments are usually interest-only on the drawn balance. Repayment period (typically 10-20 years): no new draws allowed. The outstanding balance amortizes over the remaining term with principal-and-interest payments. A $100,000 HELOC at 8.5% with $60,000 drawn: draw-period IO payment $425/month. After the draw period ends, repayment over 15 years: $590/month (+$165). The transition from interest-only to amortized payments is the biggest financial risk - many borrowers are caught off guard by the payment increase when the draw period expires.

How Much Can You Borrow with a HELOC?

Lenders typically allow combined loan-to-value (CLTV) up to 80-85%. A $500,000 home with a $300,000 first mortgage: available equity at 85% CLTV = ($500,000 x 0.85) - $300,000 = $125,000. Some lenders allow 90% CLTV for excellent credit. A $400,000 home with a $200,000 mortgage: at 80% = $120,000. At 85% = $140,000. At 90% = $160,000. The credit limit is approved at opening, but you draw only what you need and pay interest only on the drawn amount. Having a $120,000 HELOC with $0 drawn costs nothing in interest (though some lenders charge annual fees of $50-$100 on open lines).

HELOC Interest Rates: Variable and Volatile

HELOC rates are almost always variable, tied to the prime rate plus a margin. Prime rate currently 8.50%: typical HELOC rate = prime + 0% to 2% = 8.50-10.50%. When the Fed raises rates, prime rises, and your HELOC rate and payment increase within one billing cycle. Rate history matters: prime was 3.25% in 2021 (HELOC rates 3.25-5.25%) and jumped to 8.50% by 2023 (HELOC rates 8.50-10.50%). A $60,000 balance at 4%: IO payment $200/month. At 8.5%: $425/month. The payment more than doubled with no change in the balance. Variable-rate risk is the primary disadvantage of HELOCs versus fixed-rate home equity loans.

HELOC vs Home Equity Loan

HELOC: revolving credit, variable rate, borrow as needed, interest-only option during draw period. Best for ongoing or uncertain expenses. Home equity loan: lump sum, fixed rate, predictable payments from day one. Best for one-time known expenses. A $50,000 home renovation: if the total cost is certain, a home equity loan at 8% fixed provides payment predictability. If the renovation is phased over 2 years with uncertain total cost, a HELOC allows drawing funds as needed. The HELOC may start with a lower rate but carries the risk of rate increases. The home equity loan rate is higher initially but never changes.

Tax Deductibility of HELOC Interest

HELOC interest is deductible only when the funds are used to buy, build, or substantially improve the home securing the line. A $60,000 HELOC draw for a kitchen renovation: interest is deductible (subject to the $750,000 combined mortgage limit). The same $60,000 used for debt consolidation or a vacation: interest is not deductible. If you use the HELOC for mixed purposes ($40,000 renovation + $20,000 debt consolidation), only the interest on the $40,000 home improvement portion is deductible. Maintain documentation of how HELOC funds are used to support the deduction if audited.

HELOC Freeze and Reduction Risks

Lenders can freeze or reduce your HELOC credit limit if home values decline significantly in your area, your creditworthiness deteriorates, or during economic downturns (as many lenders did in 2008-2009). A $100,000 HELOC frozen at $40,000 drawn: you cannot access the remaining $60,000 even though it was originally approved. This risk means you should not rely on a HELOC as your sole emergency fund or count on future draws that have not yet been made. If you know you need the full amount, draw it at opening and keep excess funds in a savings account. The interest cost on the extra drawn amount is the price of certainty.

HELOC Payoff Strategies

Making principal payments during the draw period accelerates payoff even though only interest is required. A $75,000 balance at 8.5%: IO minimum $531/month. Paying $800/month ($269 extra to principal): balance reduced to $58,900 after 5 years versus $75,000 with IO only. At repayment period start, the lower balance produces a lower amortized payment ($458 vs $590) and less total interest. The discipline to pay above the IO minimum is the difference between a HELOC being a useful financial tool and a long-term debt trap. Set automatic payments above the minimum to ensure principal reduction occurs every month regardless of spending temptation.

Frequently asked questions