HELOC Calculator

A HELOC is a revolving credit line secured by your home, similar in mechanics to a credit card but with the home as collateral. You're approved for a maximum credit limit based on your home's appraised value minus your existing mortgage balance, capped by a combined loan-to-value ratio (CLTV) the lender chooses — typically 80–90%.

A HELOC has two phases. The draw period (usually 10 years) lets you borrow and repay as needed, with most lenders requiring only interest-only payments on the outstanding balance. The repayment period (usually 10–20 years) closes the line to new draws and amortizes the remaining balance into principal+interest payments.

Rates are almost always variable, indexed to the Wall Street Journal Prime Rate plus a margin set by the lender. When the Fed raises short-term rates, your HELOC rate moves with them — typically the next billing cycle. A 2-percentage-point rate increase on a $50,000 balance adds about $1,000 a year in interest with no change in your behavior.

HELOC: variable rate, revolving, interest-only during the draw period, no closing costs at most banks. Best for ongoing or unpredictable expenses (a multi-phase remodel, college tuition spread over four years, a small-business cash-flow buffer).

Cash-out refinance: fixed rate, replaces the existing mortgage, full closing costs (~2–5% of the new loan). Best when you can lock in a lower rate than your existing mortgage and need a single large lump sum. Bad idea when your existing mortgage rate is below current market — you'd be raising the rate on the entire balance.

Home equity loan: fixed rate, lump sum, second lien behind the existing mortgage. Best for a single known expense (a roof replacement, a defined renovation) when you want predictable payments and don't need ongoing access to funds.

The home is collateral. Missing HELOC payments can trigger foreclosure on a house you've otherwise paid down for years. Don't use a HELOC to fund anything where the income to repay isn't already locked in.

Payment shock at the end of the draw period is the most common HELOC mistake. A $100,000 balance at 8% as interest-only is $667/month; the same balance amortized over 15 years is about $955/month — a $288/month jump that arrives all at once. Run the repayment-period number before you draw the line, and treat it as the real monthly cost.

Lenders can freeze or reduce a HELOC if your home's value drops or your credit profile changes. The 2008–2010 cycle saw widespread HELOC freezes; lenders are within their rights to do this. Treating an open HELOC as a permanent emergency fund is fragile — keep some cash savings independent of the line.

Home improvements that increase the property's value, especially kitchens, bathrooms, and energy-efficiency upgrades that typically recoup 60–75% of cost at sale. Using a HELOC here also preserves the mortgage-interest deduction under post-2017 tax rules, since the funds 'substantially improve' the securing residence.

Bridge financing while selling one home and buying another, where the timing gap is measured in months and a HELOC drawn against the departing home is cheaper than a hard-money bridge loan. Close the HELOC at sale and the total interest cost is usually a fraction of bridge-loan origination fees.

Higher-rate debt consolidation, where the math is favorable: paying off a $25,000 credit-card balance at 22% APR with a HELOC at 9% saves about $3,250/year in interest. The catch is behavioral — about half of consolidators rebuild credit-card balances within two years, ending up with both debts.

Small-business working capital for established owners with a defined receivable cycle. A HELOC drawn for 60 days to bridge a delivered-but-unpaid invoice is dramatically cheaper than merchant cash advances or short-term business loans. Repay aggressively, treat the HELOC as transactional capital, and never carry the balance into the next quarter.

Credit score of 680+ for the best rates, 620+ minimum at most banks. FICO scores below 700 typically add 0.5–1.5 percentage points to the margin over Prime.

Debt-to-income ratio under 43% including the new HELOC payment, calculated using the lender's assumed fully-drawn balance — not your expected actual draw. This is the line that surprises borrowers most: even if you only plan to use $20,000, the lender qualifies you against the full approved limit.

Current appraisal or AVM (automated valuation model) within the lender's tolerance. Banks have become more cautious post-2022 housing slowdown; budget 2–4 weeks for the appraisal and don't assume Zillow's estimate will match.

Documentation typically requested: two recent pay stubs, two years of W-2s or tax returns (self-employed: three years), current mortgage statement, homeowner's insurance declaration, and government ID. Most banks close a HELOC in 30–45 days.

Start with the maximum line. At an 85% CLTV cap, the lender lets the combined debt reach $450,000 × 0.85 = $382,500. Subtract the $220,000 first mortgage and the maximum HELOC line is $162,500. Most borrowers don't draw the full amount — assume you draw $50,000 to remodel a kitchen.

During the 10-year draw period at a Prime + 0.5% rate of 8.5%, the interest-only payment is $50,000 × 8.5% ÷ 12 = $354/month. That's the manageable number borrowers fixate on. Over the full 10-year draw period, you'll have paid about $42,500 in interest with the $50,000 principal still owed.

When the line enters the 20-year repayment period, the payment recalculates to fully amortize the $50,000 balance at 8.5%. That payment jumps to roughly $434/month — a 22% increase on this balance. On a $100,000 balance the same math jumps the payment from $708 to $867. Total cost over the life of the line: ~$42,500 interest-only + ~$104,160 amortized = about $146,660, meaning $96,660 of interest on a $50,000 draw. The lesson: budget for the repayment-period payment from day one, not the comfortable interest-only number.