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A home equity line of credit (HELOC) lets you borrow against the equity in your home using a revolving credit line. During the draw period, typically 5 to 10 years, you pay only interest on the amount you have drawn. When the draw period ends, the repayment period begins and you must repay the full balance with principal and interest over 10 to 20 years. This HELOC calculator estimates your maximum credit line based on your home value, mortgage balance, and lender CLTV limit, then calculates the interest-only payment during the draw period and the higher payment required during repayment. Because HELOC rates are variable, actual payments may differ from these estimates.
Your maximum HELOC credit line depends on your home value, current mortgage balance, and the lender's maximum combined loan-to-value (CLTV) ratio.
Maximum Available Credit Line
$70,000.00
(Home value × 80% − mortgage balance)
Enter your drawn amount and terms to see interest-only draw payments and the repayment-period payment. HELOC rates are variable and may change over time; this calculator uses a fixed rate for estimation purposes.
Making extra payments toward principal during the draw or repayment period reduces your balance faster, lowering total interest and shortening the payoff timeline.
Interest-Only Payment (Draw Period)
$354.17/mo
for 120 months (10 years)
Repayment Payment (Principal + Interest)
$433.91/mo
for 240 months (20 years)
Payment Jump at End of Draw Period
Your monthly payment increases from $354.17 to $433.91 (+$79.74). This is a 23% increase.
Total Interest
$96,638.80
Total Cost
$146,638.80
Draw-Period Interest
$42,500.40
Important: HELOCs use variable interest rates tied to the prime rate. The calculations above assume a fixed rate for the entire term. Actual payments will vary as the rate adjusts. This estimate is for planning purposes only and does not constitute a loan offer.
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During the draw period of a home equity line of credit, most borrowers make interest-only payments. This means your monthly obligation is simply the drawn balance multiplied by the monthly rate. The formula is straightforward: monthly interest payment equals the HELOC balance times the annual percentage rate divided by 12.
For a $50,000 balance at 8.5% APR, the interest-only payment is approximately $354.17 per month. If rates rise to 9.5%, the same balance costs $395.83 per month, an increase of about $42. Because HELOC rates are variable, your payment can change from month to month as the underlying index moves. The calculator above uses the rate you enter, so you can model different rate scenarios by adjusting the rate slider.
During the interest-only period, your principal balance does not decrease unless you voluntarily make extra payments. This means the full drawn amount must still be repaid once the repayment period begins. Understanding this is essential for budgeting, because the transition from interest-only to amortizing payments is the single largest source of payment shock for HELOC borrowers.
A HELOC has two distinct phases. The draw period, usually 5 to 10 years, is when you can access funds from the credit line up to your approved limit. During this phase, the minimum required payment is typically interest only on the outstanding balance. Some lenders require a small principal payment (often 1% to 2% of the balance), but the standard structure is interest-only.
The repayment period, typically 10 to 20 years, begins immediately after the draw period closes. At that point, you can no longer withdraw additional funds, and your payment jumps to a fully amortizing level that covers both principal and interest. The new payment is calculated using the standard loan amortization formula applied to the remaining balance over the repayment term.
Worked Example: $50,000 HELOC at 8.5%, 10-Year Draw, 20-Year Repayment
Draw period (120 months): Interest-only payment of approximately $354.17/month. Total interest paid during the draw: $42,500. Repayment period (240 months): Monthly payment jumps to approximately $433.62/month (principal + interest). Total repayment cost: $104,069. Payment jump: from $354.17 to $433.62, an increase of $79.45 per month (about 22%). Total interest over both periods: roughly $96,569 on a $50,000 draw. These figures assume a constant rate and are for illustration only.
The draw and repayment structure means a HELOC is not comparable to a standard fixed-rate home equity loan. With a home equity loan, you receive a lump sum and begin repaying immediately with a predictable payment. A HELOC offers flexibility during the draw period but introduces uncertainty about the eventual repayment cost because of variable rates and the deferred principal obligation.
The amount you can borrow through a HELOC is governed by your combined loan-to-value (CLTV) ratio. CLTV is the total of all mortgage debt on the property (your first mortgage plus the HELOC) divided by the home's appraised value, expressed as a percentage. Most lenders set a maximum CLTV between 80% and 90%.
The borrowing limit formula is: maximum HELOC equals (home value multiplied by CLTV percentage) minus your current mortgage balance. For a $400,000 home with a $250,000 first mortgage, an 80% CLTV cap yields a maximum HELOC of $70,000 ($400,000 multiplied by 0.80 minus $250,000). The same home at 85% CLTV would allow up to $90,000, and at 90% CLTV, up to $110,000.
Lenders also evaluate your credit score, debt-to-income ratio, payment history, and the amount of equity you have built. Borrowers with higher credit scores and lower DTI ratios tend to qualify for higher CLTV limits and better rates. Most lenders require at least 15% to 20% equity before approving a HELOC. If your home value has appreciated since purchase, a new appraisal may increase your available credit line. The calculator above computes the maximum based on the CLTV you enter, so you can see how different CLTV levels affect your borrowing capacity.
Making extra payments toward your HELOC balance is one of the most effective ways to reduce total interest and shorten your repayment timeline. Because most HELOCs have no prepayment penalty, you can apply extra funds at any time. The impact depends on whether you pay extra during the draw period or the repayment period.
During the draw period, extra payments reduce the outstanding principal. Since interest accrues on the daily balance, every dollar of principal reduction lowers your interest charge going forward. A $200/month extra payment on a $50,000 HELOC at 8.5% during a 10-year draw period reduces the balance by approximately $24,000 in principal (before interest savings are factored), which means the repayment-period starting balance is substantially lower and the required amortizing payment drops accordingly.
During the repayment period, extra payments accelerate the amortization schedule. The same $200/month extra on a 20-year repayment schedule can shave roughly 3 to 4 years off the payoff timeline and save thousands in interest. The calculator above models both scenarios. Select "Draw Period" or "Repayment Period" in the extra payments section to compare the impact.
A $50,000 HELOC is a common draw amount for home improvements, debt consolidation, or major expenses. The monthly payment depends on the rate, the draw period length, and whether you are in the draw or repayment phase. Below is a breakdown at several rate levels, assuming a 10-year draw and 20-year repayment.
$50,000 HELOC Monthly Payments at Various Rates (10-Year Draw, 20-Year Repayment)
At 7.0%: Interest-only draw payment $291.67/month. Repayment payment $387.65/month. Payment jump: +$95.98 (33% increase). At 8.5%: Interest-only draw payment $354.17/month. Repayment payment $433.62/month. Payment jump: +$79.45 (22% increase). At 10.0%: Interest-only draw payment $416.67/month. Repayment payment $482.51/month. Payment jump: +$65.84 (16% increase). These are estimates based on a constant rate. Variable rates may produce different results.
One important pattern is that the percentage payment jump actually decreases at higher rates, even though the dollar amounts increase. This happens because the interest-only payment is proportionally larger at higher rates, leaving a smaller gap to the amortizing payment. However, the total cost of the HELOC rises significantly at higher rates. At 8.5%, total interest over the full 30-year span is roughly $96,569. At 10.0%, total interest jumps to roughly $116,101, an increase of nearly $20,000 on the same $50,000 draw.
When planning a $50,000 draw, consider both the monthly payment you can afford during repayment and the total interest cost. Shorter repayment periods reduce total interest but raise the monthly payment. Use the calculator above to experiment with different term combinations and find a structure that fits your budget while minimizing total cost.
Browse all tools on the Home Buying Calculators hub. Use the PMI Calculator to estimate private mortgage insurance costs, or the Refinance Break-Even Calculator to evaluate whether refinancing your first mortgage saves money overall. The DTI Calculator can help you check whether adding a HELOC payment keeps your total debt-to-income ratio within lender limits, and the Debt Payoff Calculator is useful if you plan to use HELOC proceeds for debt consolidation.