HELOC Amortization Table: Estimate Payments and Balance

A HELOC amortization table shows how each scheduled payment is split between interest and principal, and how the balance changes over time. This calculator estimates a fixed-rate, fully amortizing payment and total interest from the amount borrowed, APR, and repayment term; it does not model the changing draw and repayment rules of every HELOC.

Formula

The calculator uses the standard level-payment amortization formula. It first finds a monthly payment that would repay the entered principal over the selected number of months at a constant monthly rate:

Payment = P × r ÷ [1 − (1 + r)⁻ⁿ]

• P is the borrowed amount in dollars.
• r is the monthly interest rate, calculated as APR ÷ 1,200 when APR is entered as a percentage per year.
• n is the number of monthly payments, calculated as years × 12.
• Payment is the monthly dollar amount, rounded to the nearest cent.

Estimated total interest is (rounded monthly payment × n) − P. Because the payment is rounded to cents, this total can differ slightly from a calculation that retains fractions of a cent throughout. The calculator’s result is an estimate, not a lender’s payment schedule.

Worked Example

Using the calculator’s defaults—$20,000 borrowed, 8% APR, and five years—the monthly rate is 0.08 ÷ 12, or 0.0066667, and the term is 5 × 12 = 60 payments.

Substitute those values into the payment formula:

$20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻⁶⁰] = $405.53 per month, rounded to cents.

Using the rounded payment, estimated total paid is $405.53 × 60 = $24,331.80. Estimated total interest is $24,331.80 − $20,000 = $4,331.80.

How to Read a HELOC Amortization Table

A full amortization table has one row for each payment period. Typical columns show the payment number or date, starting balance, payment, interest charged, principal repaid, and ending balance. For a simple fixed-rate monthly calculation:

• Monthly interest is the starting balance multiplied by the monthly rate.
• Principal repaid is the payment minus that month’s interest.
• The ending balance is the starting balance minus principal repaid.

With the example’s first payment, monthly interest is about $133.33 ($20,000 × 0.0066667). Of the $405.53 payment, about $272.20 reduces principal, leaving an estimated $19,727.80 balance. Later payments generally contain less interest and more principal because interest is calculated on a declining balance. Minor cent-rounding differences may affect the final payment.

This page calculates the level payment and total interest, not every row of the table. A lender’s statement or schedule can include payment dates, rounding conventions, fees, and changing rates that this estimate does not reproduce.

Why HELOC Payments Can Differ

A home equity line of credit is revolving credit secured by home equity. Unlike a typical installment loan, it may have a period when the borrower can draw funds, followed by a repayment period. The terms vary by agreement, so an amortization table for a HELOC should be based on the actual balance, rate, payment method, and remaining repayment term—not simply the maximum line amount.

During a draw period, a required payment may be calculated differently from a fully amortizing payment. If a contract permits interest-only payments during that phase, those payments do not reduce principal. The balance can remain unchanged if no principal is paid and no additional borrowing or charges occur. When the repayment phase begins, payment requirements may change; a fully amortizing schedule can produce a larger payment than an interest-only calculation. Variable rates or further draws can also change the schedule.

For a useful estimate, enter the amount actually outstanding or expected to be repaid, not the unused credit limit. If the rate can change, a single APR is only a snapshot assumption. Recalculate with another rate or term to see how the estimated payment changes, while treating each result as a separate hypothetical rather than a prediction.

Inputs, Uses, and Limits

Enter the principal in dollars, the annual percentage rate as a percentage (for example, enter 8 for 8%), and the term in years. The APR and term must reflect the repayment period being modeled. If a lender provides a monthly rate instead, convert it to an annual percentage input consistently before using this calculator; do not enter a monthly percentage as though it were an annual APR.

This estimate can help explain the mechanics of paying down a fixed balance or compare hypothetical terms. It does not establish the actual amount due on a HELOC. The contract and current account information determine applicable rates, payment rules, timing, and charges. Obtain those figures from the lender or account documents.

Common sources of mismatch include using a credit limit instead of the drawn balance, confusing APR with a monthly rate, assuming the draw period is the amortization term, and overlooking that a variable rate can change. Do not infer a future payment from a table that assumes a fixed rate if the actual agreement allows the rate to move.

Assumptions

• The interest rate is fixed for the modeled term.
• Payments are made monthly at the end of each period.
• Interest is compounded monthly using APR ÷ 12 as the monthly rate.
• The full balance is repaid through equal monthly payments; no new draws or extra payments are made.
• Fees, taxes, insurance, and other charges are not included.

Frequently Asked Questions

What does a HELOC amortization table show?
It lays out each payment period’s starting balance, interest, principal paid, payment amount, and ending balance. A lender’s table may reflect terms and rate changes not represented by a basic estimate.

Are HELOC payments always fully amortizing?
No. Payment rules depend on the agreement and phase of the line. Some arrangements calculate draw-period payments differently from repayment-period payments, so check the account terms rather than assuming a level principal-and-interest payment throughout.

Why does my HELOC payment differ from this estimate?
The actual balance, variable rate, payment calculation, repayment term, payment dates, fees, and rounding can all differ from the calculator’s assumptions. Compare the inputs with your current statement and lender disclosures.

Does an interest-only payment reduce the HELOC balance?
Not if the payment covers only the interest charged and there are no other principal payments. New draws or charges can increase the balance; the exact treatment depends on the agreement.

Can I use the HELOC credit limit as the loan amount?
Only if the full limit is actually borrowed and outstanding. For an estimate of repayment on an existing balance, use the amount owed, not unused available credit.

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

Related

• Amortization Table Example: Monthly Loan Breakdown
• Amortization Table in Excel: Formula and Example
• Quarterly Amortization Table Calculator and Formula

in p | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan 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