HELOC Cost: Estimate Payments, Interest and Fees

A HELOC’s cost depends on how much you borrow, the interest rate, how long you carry a balance, and any lender fees. This calculator estimates a fixed-rate monthly payment and total interest for a chosen balance and term; enter the figures supplied by a lender to see the arithmetic, not a quote for an actual HELOC.

Formula

The calculator uses the standard level-payment loan formula. It assumes the balance is repaid in equal monthly payments at a fixed annual percentage rate:

• Monthly payment = round[ P × r / (1 − (1 + r)⁻ⁿ), 2 ]
• Total interest = monthly payment × n − P
• r = APR ÷ 1,200, the monthly interest rate as a decimal.
• P is the amount borrowed in dollars; n is the number of monthly payments, calculated as years × 12.

The payment is rounded to the nearest cent before total interest is calculated. Actual HELOCs may have changing rates, changing balances, different payment rules, and fees, so this is a simplified comparison of principal-and-interest arithmetic.

Worked Example

Using the calculator’s defaults—$20,000 borrowed, 8% APR, and five years—the monthly rate is 8 ÷ 1,200 = 0.0066667, and the term is 5 × 12 = 60 monthly payments.

1. Payment = $20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻⁶⁰].
2. The unrounded result is about $405.53; rounded to cents, the monthly payment is $405.53.
3. Total of payments = $405.53 × 60 = $24,331.80.
4. Total interest = $24,331.80 − $20,000 = $4,331.80.

Assumptions

• The interest rate stays fixed throughout the repayment term.
• Payments are made monthly, with the first payment one month after borrowing.
• Interest compounds monthly at APR divided by 12.
• The estimate excludes lender fees, taxes, insurance, PMI, escrow, and any costs not entered into the calculator.

What Determines HELOC Cost?

A home equity line of credit (HELOC) is a revolving credit line secured by a home. Rather than receiving all the money at once, a borrower can draw funds as needed, subject to the line’s terms. That means the cost is not simply the amount of credit offered: it depends on how much is actually drawn and for how long it remains outstanding.

• Balance and timing: Interest generally accrues on amounts borrowed, not the unused portion of a credit line. Drawing money earlier or keeping it outstanding longer can increase interest.
• Rate structure: Many HELOCs have variable rates, which can change over time. The calculator holds APR constant, so it cannot predict the cost of a changing rate.
• Payment rules: Payment amounts can differ during a draw period and a repayment period. A required payment during a draw period may not pay off principal in the way this level-payment example does.
• Fees: Application, valuation, annual, transaction, or closing-related charges may apply, depending on the lender and agreement. Ask for an itemized list and when each charge is due.

For instance, a $20,000 balance at 8% held for a year would accrue roughly $1,600 in simple interest if the balance and rate stayed unchanged and no payments reduced principal. This is an illustration only: actual interest calculation and payment timing depend on the agreement. It also shows why a payment estimate for a five-year payoff is not the same thing as the cost of carrying a balance during a HELOC’s draw period.

How to Estimate Your Own Cost

Use the balance you expect to draw, rather than the maximum credit line, and obtain the actual APR and payment period from the lender’s disclosures. If the rate is variable, model more than one rate scenario instead of treating one estimate as certain. Add known fees separately; this calculator does not include them.

• Enter an estimated outstanding balance, not an undrawn limit.
• Use the APR and repayment term shown in the lender’s documents.
• Compare the estimate with the stated minimum payment and payment schedule.
• For a variable rate or multiple draws, calculate separate scenarios or request a transaction-specific estimate from the lender.

Do not treat “total interest” as the total cost of the credit line. It excludes fees and assumes a fixed balance is fully amortized on a fixed schedule. A lender’s disclosure should show the applicable rates, charges, and payment terms for that account.

HELOC Cost Compared With Other Borrowing

A HELOC differs from a home equity loan, which generally advances a lump sum rather than allowing repeated draws, and from an unsecured personal loan, which is not secured by the home. Each product can have different rate structures, fees, and repayment rules. A useful comparison looks at the same amount borrowed over the same period and includes fees—not just a quoted interest rate or monthly payment.

Because a HELOC is secured by the home, missed payments can have serious consequences under the loan agreement. The line’s available credit is not the same as cash already borrowed, and a lender may impose conditions affecting access. Read the agreement carefully and check the lender’s current figures; this calculator does not model access restrictions or consequences of missed payments.

Frequently Asked Questions

How much does a $20,000 HELOC cost per month?
With the calculator’s example assumptions of 8% APR and a five-year fixed repayment, the estimated payment is $405.53 a month. A real HELOC’s payment may differ because its rate, fees, balance, and payment terms may differ.

Does a HELOC charge interest on the full credit limit?
Interest is generally based on the borrowed balance, not simply the amount of credit offered. Check the lender’s agreement for how interest accrues and whether other account charges apply.

Are HELOC payments fixed?
Not necessarily. Rates may vary, and payment requirements can change with the balance, rate, and phase of the credit line. The calculator assumes a fixed rate and equal payments.

What fees can add to a HELOC’s cost?
Possible charges include application, property valuation, annual, transaction, or closing-related fees. Which charges apply and their amounts depend on the lender and agreement, so request an itemized disclosure.

Is a HELOC calculator’s total interest the full cost?
No. This estimate excludes fees and assumes a fixed-rate, fully amortizing balance. It also cannot model variable-rate changes or a schedule involving multiple draws.

This result is an estimate for educational purposes; the lender’s disclosure gives the exact figures.

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in p | HELOC balance | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Repayment term | years | 5 | 0.0833 | 50
out pmt | Monthly payment | $ | round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2