HELOC Calculator

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Reviewed by: David Chen, CFA
David is a Chartered Financial Analyst specializing in consumer credit and home equity products. He has over 15 years of experience helping homeowners leverage their equity responsibly.

This 4-in-1 HELOC (Home Equity Line of Credit) calculator helps you model the amortized repayment phase. Enter any three variables—Loan Amount, Annual Rate, Term, or Monthly Payment—and we will solve for the fourth.

Loan Amount ($) (P)

Annual Rate (%) (R)

Loan Term (Years) (T)

Monthly Payment ($) (M)

HELOC Payment Formulas

Solve for Monthly Payment (M):
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]

Solve for Loan Amount (P):
P = M [ (1 + i)^n – 1 ] / [ i(1 + i)^n ]

Solve for Loan Term (T):
T = ln(M / (M – Pi)) / (n * ln(1 + i))

Solve for Rate (R):
Solved iteratively (no direct formula)

Formula Source: Investopedia

Formula Variables

(P) Loan Amount: The total amount you have drawn from your line of credit that you wish to amortize (repay with interest).
(R) Annual Rate: The annual interest rate (APR) for your HELOC’s repayment period.
(T) Loan Term: The number of years in your HELOC’s repayment period (e.g., 20 years).
(M) Monthly Payment: The fixed monthly payment (Principal & Interest) required to pay off the loan in the specified term.
(i) Monthly Rate: The annual rate divided by 12.
(n) Total Payments: The total number of payments (Term in years * 12).

Related Calculators

What is a HELOC Calculator?

A HELOC (Home Equity Line of Credit) Calculator is a tool designed to help homeowners understand the costs associated with their line of credit. A HELOC typically has two phases: the “draw period” (often 10 years) where you can withdraw funds, and the “repayment period” (often 20 years) where you must pay back the borrowed amount with interest.

This calculator focuses on the repayment period, helping you solve for any one variable (loan amount, interest rate, term, or monthly payment) if you know the other three. This is crucial for budgeting and understanding how much your payments will be once the draw period ends and amortization begins.

By entering any three values, you can instantly find the missing fourth. For example, you can determine the monthly payment required to pay off a $50,000 balance over 20 years at an 8% interest rate. Or, you can find out how long it will take to pay off your balance if you can only afford a certain monthly payment.

How to Calculate HELOC Payments (Example)

Identify Your Variables
Let’s say you are entering the repayment period with a HELOC balance (P) of $50,000. Your bank sets the amortizing Annual Rate (R) at 8.0%, and the Repayment Term (T) is 20 years. You want to find your Monthly Payment (M).
Convert Annual Rate to Monthly (i)
First, convert the annual rate to a monthly decimal: i = (8.0% / 100) / 12 = 0.08 / 12 = 0.006667
Calculate Total Number of Payments (n)
Next, find the total number of monthly payments: n = 20 Years * 12 Months/Year = 240 payments
Apply the Amortization Formula
Use the standard loan payment formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
M = 50,000 [ 0.006667 * (1 + 0.006667)^240 ] / [ (1 + 0.006667)^240 – 1 ]
M = 50,000 [ 0.006667 * (4.9268) ] / [ 4.9268 – 1 ]
M = 50,000 [ 0.032847 ] / [ 3.9268 ]
M = 50,000 * 0.008364
M = $418.22
Final Result
Your fixed monthly principal and interest payment for the 20-year repayment period will be $418.22.

Frequently Asked Questions (FAQ)

What’s the difference between a HELOC and a Home Equity Loan?

A Home Equity Loan (HEL) is a one-time lump sum loan with a fixed interest rate and fixed monthly payments. A HELOC (Home Equity Line of Credit) is a revolving line of credit, like a credit card, with a variable interest rate. A HELOC has a “draw period” (to borrow) and a “repayment period” (to pay back).

Why does this calculator use a fixed term and rate?

This calculator models the repayment period of a HELOC, which is when you are no longer drawing money and are paying down the principal and interest. While many HELOCs have variable rates, this tool allows you to model a “what-if” scenario using a fixed rate to budget for your payments.

How do I find my interest rate (R)?

If you know your loan amount, term, and monthly payment, you can use this calculator to solve for the interest rate. Just leave the “Annual Rate (%)” field empty, fill in the other three, and click “Calculate.” Can I solve for the loan term (T)?

Yes. If you know how much you borrowed, your interest rate, and how much you can afford to pay each month, this calculator can tell you how many years it will take to pay off your HELOC. Leave the “Loan Term (Years)” field empty and fill the other three.

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