HELOC Amortization Table Calculator and Payment Guide

A HELOC amortization table calculator estimates the monthly payment, total interest, and remaining balance for a home equity line of credit when you enter a balance, APR, and repayment term. This calculator models a fully drawn balance repaid through equal monthly payments; its schedule is an estimate, not a lender’s official payment plan.

Formula

The calculator uses the standard fixed-rate, fully amortizing payment formula, with the monthly payment rounded to the nearest cent:

Payment = round(P × r ÷ [1 − (1 + r)⁻ⁿ], 2)

• P is the HELOC balance being repaid, in dollars.
• r is the monthly interest rate, calculated as APR ÷ 1,200. APR is entered as a percentage per year.
• n is the repayment term in months, calculated as years × 12.
• Payment is the estimated monthly principal-and-interest payment, in dollars.

Total interest is estimated as the rounded monthly payment multiplied by the number of months, minus the starting balance: Interest = Payment × n − P. The final-balance formula applies monthly interest and subtracts each level payment. The displayed ending balance is floored at zero to prevent a small negative value caused by rounding.

Worked Example

Using the calculator’s default inputs: balance P = $20,000, APR = 8%, and term = 5 years.

1. Convert the annual percentage rate to a monthly decimal rate: r = 8 ÷ 1,200 = 0.0066666667.
2. Convert the repayment term to months: n = 5 × 12 = 60.
3. Calculate the level payment: round[$20,000 × 0.0066666667 ÷ (1 − (1.0066666667)⁻⁶⁰), 2] = $405.53 per month.
4. Calculate total interest using the rounded payment: $405.53 × 60 − $20,000 = $4,331.80.
5. After 60 scheduled payments, the calculated remaining balance is approximately zero; the displayed result is $0.00.

The example assumes that the balance and rate stay unchanged and that the same payment is made on schedule. A real account may use different payment rules, a changing rate, or a different balance each month.

Assumptions

• The interest rate is fixed for the entire modeled repayment term.
• Payments are equal, made monthly at the end of each monthly period, and include principal and interest.
• Interest compounds monthly at APR ÷ 12.
• The model excludes fees, taxes, insurance, PMI, escrow, new borrowing, and lender-specific payment adjustments.

How to Read a HELOC Amortization Table

An amortization table lists each payment period and shows how the payment is divided between interest and principal. A typical row includes the starting balance, payment, interest charged for that period, principal repaid, and ending balance. To create a row, multiply the starting balance by the monthly rate to estimate interest; subtract that interest from the payment to find principal repaid; then subtract principal from the starting balance.

For example, at the default 8% APR, the first month’s interest on $20,000 is about $133.33 ($20,000 × 0.0066666667). Of the $405.53 payment, about $272.20 therefore reduces principal, leaving a balance of about $19,727.80. As the balance declines, the interest portion generally shrinks and more of a level payment goes toward principal.

This page calculates summary results rather than printing every monthly row. For a detailed schedule, apply the row-by-row method to the actual balance, payment dates, and rate rules. Cent rounding can create a small difference in the last payment, so a lender’s final installment may be adjusted.

HELOC Draw and Repayment Periods

A home equity line of credit is revolving credit secured by home equity. Many HELOCs distinguish between a draw period, when the borrower may access available credit under the account’s terms, and a repayment period, when outstanding principal must be repaid. The length and mechanics of these periods are contract-specific; use the lender’s documents to identify the relevant dates, balance, and payment calculation.

This calculator applies an amortizing repayment schedule to the balance entered. It does not model new advances, withdrawals, a draw-period payment that covers only interest, or a transition from one phase to another. If a balance changes during the period, the original table no longer describes the account: interest and payments need to be recalculated using the updated balance and applicable terms.

Choosing Inputs and Understanding Limits

Enter the amount currently owed, not the full credit limit, unless the entire line has actually been drawn. Enter the APR that applies to the balance and the number of years over which that balance is scheduled to be repaid. Obtain the actual rate, payment terms, and any rate-change rules from the lender’s disclosure or account documents. The default values are examples, not quoted terms.

• Variable APR: If the rate changes, a fixed-rate estimate cannot forecast later payments or total interest accurately. Recalculate with a rate that applies to a particular period, or use the lender’s method for changing-rate balances.
• Changing balance: Further borrowing or payments larger than the modeled amount change the schedule. The calculator assumes no additional advances and a constant payment.
• Interest-only payments: An interest-only amount is not the same as a payment that amortizes principal over a defined term. This calculator uses equal principal-and-interest payments.
• Rounding and timing: Lenders may calculate interest using daily balances or other contract terms. Payment dates, rounding, and fees can make actual figures differ.

The calculator is useful for understanding the arithmetic of repaying a fixed balance, comparing hypothetical terms, and seeing how an amortizing payment changes the balance over time. It cannot determine account eligibility, available credit, a lender’s required payment, or what a particular borrower can afford.

Frequently Asked Questions

Can I use an amortization calculator for a HELOC?
Yes, for an estimate if you enter the balance, applicable APR, and repayment term. The result is most representative when the balance and rate stay fixed and the payments are level.

Does a HELOC amortization table include the draw period?
Not in this calculator. It models repayment of the entered balance and does not simulate draws, new borrowing, or draw-period payment rules.

Why does my lender’s payment differ from this estimate?
The lender may use a variable rate, daily interest calculations, fees, a different payment term, or contract-specific rounding and payment rules. Check the account disclosure for the method that applies.

Can I make extra payments?
This calculator does not include extra payments. An additional principal payment can change the remaining balance and interest, but its treatment and any applicable conditions depend on the account terms.

What happens if the HELOC rate changes?
A changed rate changes the interest charged and may change the required payment or payoff time. This fixed-rate calculation does not predict those adjustments; consult the lender’s stated method.

This result is an estimate for education, and the lender’s disclosure gives the exact figures.

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in bal | 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 | Estimated monthly payment | $ | round(bal * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) | 2
out int | Total interest | $ | pmt * yrs * 12 - bal | 2
out end | Balance after final payment | $ | max(0, bal * (1 + apr / 1200) ^ (yrs * 12) - pmt * ((1 + apr / 1200) ^ (yrs * 12) - 1) / (apr / 1200)) | 2