The basic formula for a HELOC payment

A HELOC payment is calculated by multiplying your current balance by your interest rate, then dividing by 12 (for a monthly payment). The formula is: (Balance × Interest Rate) ÷ 12 = Monthly Payment.

This calculation applies during the draw period — the time when you can borrow money from your HELOC. Most HELOCs have a draw period of 5 to 10 years. During this time, you typically pay interest only, not principal. That means your payment covers only the cost of borrowing, not the amount you owe.

Here is a concrete example: if your HELOC balance is $25,000 and your interest rate is 8 percent per year, your monthly payment would be ($25,000 × 0.08) ÷ 12 = $166.67. That payment covers interest only and does not reduce what you owe.

Key Takeaways

  • During the draw period, your HELOC payment is calculated by multiplying your balance by your annual interest rate and dividing by 12 for a monthly amount.
  • Interest rates on HELOCs are variable, meaning they change when the market rate changes, so your payment will fluctuate throughout the year.
  • When the draw period ends, your HELOC moves into a repayment period where you must pay both principal and interest, and your payment will increase significantly.
  • Your lender provides a statement each month showing your current balance, interest rate, and minimum payment due.
  • Paying more than the minimum during the draw period reduces your balance and lowers future payments.

Why your HELOC rate changes and what that means for your payment

Unlike a fixed-rate mortgage or loan, a HELOC interest rate is variable. This means it moves up and down based on a market rate called the prime rate, which is set by the Federal Reserve. Your lender adds a margin (usually 0.5 to 2 percent) to the prime rate to get your actual rate.

When the prime rate rises, your interest rate rises, and your monthly payment goes up. When the prime rate falls, your rate and payment fall. This is why a HELOC payment is not fixed — you cannot predict exactly what you will owe six months from now.

Your lender is required to send you a statement each month showing your current balance, current interest rate, and the minimum payment due. This statement is the most accurate way to know what you owe that month. Do not rely on last month's payment as a guide.

What happens when your draw period ends

After the draw period (typically 5 to 10 years), your HELOC enters a repayment period, usually lasting 10 to 20 years. During repayment, you can no longer borrow new money, and your payment changes dramatically.

Instead of paying interest only, you now pay both principal and interest. Your lender calculates a new payment using an amortization schedule — the same method used for mortgages. This payment is much higher than your draw-period payment because you are paying down the balance over a fixed number of years.

For example, if you still owe $25,000 when repayment begins, and your rate is 8 percent, and you have 10 years to repay, your new monthly payment might be around $300 — nearly double what you were paying before. This is why many people are surprised by the jump: they have been paying $166 a month and suddenly owe $300.

How to calculate what you will owe in the repayment period

To estimate your repayment-period payment, you need three numbers: your remaining balance when repayment starts, your interest rate at that time, and the length of the repayment period (usually stated in your HELOC agreement).

The easiest method is to use an online amortization calculator — search "amortization calculator" and enter your balance, rate, and loan term in years. The calculator will show you the monthly payment. If you prefer to calculate by hand, the formula is more complex and involves logarithms, so a calculator is practical.

Keep in mind that your interest rate may change between now and when repayment begins, so this is an estimate, not a may provide. Your lender will send you a notice before the repayment period starts, telling you the exact payment amount.

How to find your current payment on your statement

Your HELOC statement lists your minimum payment due. This is the amount your lender requires you to pay each month. During the draw period, this is usually the interest-only amount calculated using the formula above.

Look for a line item labeled "Minimum Payment Due" or "Payment Due." Your statement also shows your current balance and current interest rate — the two numbers you need to verify the payment calculation yourself.

If you do not receive a statement, contact your lender directly. They can tell you your current balance, rate, and minimum payment. You can also log into your online account if your lender offers one.

What happens if you pay more than the minimum

During the draw period, you are not required to pay down your balance — only the interest. But you can pay more than the minimum at any time without penalty. Any amount above the minimum goes directly toward reducing your balance.

Paying extra during the draw period has two benefits: it lowers the amount you owe when repayment begins, and it reduces your future payments. If you pay $500 a month instead of the $166 minimum, you are paying $334 toward principal, which shrinks your balance faster.

Some people use this strategy to prepare for the payment shock that comes when the draw period ends. By paying principal during the draw period, they reduce the balance that will be amortized during repayment, keeping the repayment payment manageable.

The difference between your HELOC and a home equity loan

A home equity loan is different from a HELOC, and the payment calculation is simpler. A home equity loan has a fixed interest rate and a fixed payment from day one. You borrow a lump sum and repay it over a set number of years (usually 5 to 15).

With a home equity loan, you calculate the payment once using an amortization calculator, and that payment stays the same for the entire loan. There is no draw period, no variable rate, and no payment shock at the end.

A HELOC is more flexible — you borrow only what you need, when you need it — but the trade-off is that your payment changes with interest rates and jumps significantly when repayment begins. Understanding which product you have is the first step to calculating your payment correctly.

Frequently Asked Questions

Why is my HELOC payment different this month than last month?

Your interest rate changed. HELOCs have variable rates tied to the prime rate, which moves throughout the year. When the prime rate changes, your rate and your monthly payment change too. Check your statement to see your new rate.

Can I pay off my HELOC early without a penalty?

Most HELOCs allow you to pay off the balance at any time without penalty. Check your loan agreement or call your lender to confirm. Paying off early stops the interest from accruing and ends your obligation.

What if I cannot afford my payment when the draw period ends?

Contact your lender before the repayment period begins. Some lenders offer options like extending the repayment period (which lowers the payment but costs more in interest) or converting to a fixed-rate loan. Do not wait until you miss a payment.

Is the interest on my HELOC tax-deductible?

HELOC interest may be deductible if you used the borrowed money to improve your home. Interest used for other purposes is generally not deductible. Consult a tax professional about your specific situation.

How do I know if my lender calculated my payment correctly?

Use the formula (Balance × Interest Rate) ÷ 12 and compare it to your statement. If the numbers do not match, call your lender and ask them to explain the difference. Some lenders round or explore fees that change the amount slightly.