Estimate your HELOC credit line and compare your interest-only draw payment against the higher repayment-period payment. Enter your home value, mortgage balance, and rate to see both phases of a home equity line of credit in 2026.
This calculator serves homeowners considering a flexible credit line secured by their home equity. You provide your home value, current mortgage balance, expected draw amount, interest rate, and the length of the draw and repayment periods, and it returns your available credit limit alongside two payments: the interest-only amount during the draw years and the principal-plus-interest amount afterward. A HELOC differs from a fixed home equity loan in two big ways — the rate is usually variable, and you borrow only what you need, when you need it. Lenders typically extend a line up to roughly 85% of your home value minus your mortgage, with the strongest rates requiring high credit and lower loan-to-value. Use it to plan a phased renovation, an emergency reserve, or ongoing expenses.
You can map out both payment phases in a couple of minutes. Here's the sequence:
Enter your home value.
A current appraisal or trusted estimate works best.
Add your mortgage balance.
Input what you still owe on your first mortgage.
Set your credit-limit cap.
Most lenders allow up to 85% combined loan-to-value; the tool calculates your line accordingly.
Enter your expected draw.
Type how much you actually plan to borrow, which may be less than your full limit.
Add the variable rate and periods.
HELOC rates sat near 7.25% in mid-2026; set your draw period (often 10 years) and repayment period (often 20).
Compare the two payments.
Review the interest-only draw payment against the higher repayment-phase payment.
Raise your draw amount and watch the repayment payment climb — that's the payment shock to plan for.
The calculator works in two stages that mirror how a HELOC actually behaves. First, it sets your credit line using the same equity math a lender uses:
Credit Limit = (Home Value × 85%) − Mortgage Balance
On a $500,000 home with a $300,000 mortgage, that's ($500,000 × 0.85) − $300,000 = $425,000 − $300,000 = $125,000 available. Then it prices the two phases. During the draw period, many HELOCs require interest only, so the payment is just the balance times the monthly rate:
Interest-Only Payment = (Balance × Annual Rate) ÷ 12
When the repayment period starts, the payment switches to full principal and interest amortized over the remaining years, which is where it spikes. Here's what that actually means: a $50,000 balance at 7.25% costs about $302 a month interest-only, but jumps to roughly $396 a month when it amortizes over 20 years — and far more on a shorter repayment term. Because the rate is variable, both numbers can rise if market rates climb, so the calculator's figures are a snapshot, not a lifetime guarantee.
The gap between your two payments is the single most important thing on the screen. That low interest-only figure during the draw period is comfortable, even tempting, but it doesn't reduce your balance at all — you're treading water. When repayment begins, the payment jumps to cover principal too, and many borrowers feel that shift hard. Think of it this way: the draw period is the easy stretch, and the repayment period is the bill coming due. Your credit limit is a ceiling, not a spending plan; drawing the full amount maximizes both payments and your risk. Because the rate floats, a rising-rate environment can push both payments higher than the calculator shows today, which is why a fixed home equity loan sometimes suits people who crave certainty. Use the result to ask whether you can comfortably afford the repayment-phase payment, not just the easy draw-period one. If only the interest-only number fits your budget, the HELOC may be riskier than it looks.
A HELOC's numbers shift with several moving parts:
HELOC rates rise and fall with the prime rate, so your payment isn't locked. A rate increase lifts both phases.
You're charged only on what you borrow, so a smaller draw means smaller payments in both periods.
A long draw period delays principal, but a short repayment period crams payoff into fewer years, spiking the payment.
The 85% limit minus your mortgage sets how large your line can be.
Borrowers above 740 generally land the best rates and the highest limits.
Some HELOCs allow principal payments during the draw period, which softens the later jump.
The Brooks family has a $520,000 home with a $310,000 mortgage. Their 85% line works out to ($520,000 × 0.85) − $310,000 = $132,000. They draw $40,000 in stages for a remodel. At a 7.25% variable rate, their interest-only draw payment is about $242 a month — easy on the budget. But once the 10-year draw period ends and repayment kicks in over 20 years, the payment rises to roughly $316. That increase is modest here only because they kept the draw small and the repayment term long.
Nina taps $100,000 of a HELOC on her $600,000 home, where she owes $250,000 (a line ceiling of $260,000). During the draw period at 7.25%, her interest-only payment is about $604 a month. When repayment begins on a 15-year schedule, the payment leaps to roughly $913 — a jump of over $300. That's payment shock in action: nothing went wrong, the loan simply started requiring principal. Planning for that higher number from day one is the whole point of running it now.
A HELOC rewards discipline and punishes wishful thinking. Keep these front of mind:
Budget for the repayment payment, not the draw payment. The easy interest-only figure ends; make sure the bigger one fits.
Pay down principal during the draw period. Chipping away early softens the eventual jump and saves interest.
Draw conservatively. Your limit isn't a target. Borrow only what a specific need requires.
Stress-test for higher rates. Because the rate floats, run the numbers a point or two higher to see if you'd still be comfortable.
Know your dates. Mark when the draw period ends so the repayment payment never surprises you.
Compare with a fixed option. If certainty matters more than flexibility, a fixed lump-sum loan may serve you better.
A HELOC calculator estimates your available credit line and shows two payments: a low interest-only payment during the draw period and a higher principal-and-interest payment during repayment. You enter your home value, mortgage balance, draw amount, and rate. It then reveals the payment jump between the two phases.
Lenders typically offer a line up to about 85% of your home's value minus your mortgage balance. On a $500,000 home with a $300,000 mortgage, that's around $125,000. Your credit score and income can reduce the limit you actually receive.
The draw period is the initial phase, often 10 years, when you can borrow from your line and usually pay interest only. Your balance doesn't shrink during this time unless you pay extra principal. When it ends, the repayment period begins and payments rise.
Your payment increases because the draw period's interest-only payments switch to full principal-and-interest payments when repayment begins. Suddenly you're paying down the balance, not just the interest. This payment shock can be significant on a large balance.
HELOC rates are usually variable, moving up and down with the prime rate, so your payment can change over time. In mid-2026 the average HELOC rate was around 7.25% to 7.47%. Some lenders offer fixed-rate conversion options on part of the balance.
A HELOC is a revolving, variable-rate credit line you draw on as needed, while a home equity loan is a fixed-rate lump sum with steady payments. Choose a HELOC for flexible or phased spending. Choose the loan for a one-time expense and predictable budgeting.
A HELOC makes sense if you need flexible access to funds over time and can comfortably afford the higher repayment-period payment. It's riskier if your budget only fits the interest-only payment or if rising rates would strain you. Because your home is collateral, treat it cautiously.
Brief disclaimer: This calculator provides estimates for educational and planning purposes only. Actual HELOC terms, rates, and limits depend on your lender, credit profile, and property appraisal. Rates referenced reflect mid-2026 data and change with market conditions. Results should be treated as planning guidance rather than financial or mortgage advice.