Equity Loan Payment Calculator Formula and Example

An equity loan payment calculator estimates the fixed monthly payment and total interest on a loan using the amount borrowed, annual percentage rate (APR), and repayment term. Enter those three figures to see the estimated payment and interest; this standard formula does not calculate a home equity line of credit (HELOC), whose balance and payments can change.

Formula

For a fixed-rate loan paid in equal monthly installments, the monthly payment is the loan principal multiplied by the monthly interest rate, divided by one minus the factor (one plus the monthly rate) raised to the negative number of payments:

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

• PMT is the monthly payment in dollars.
• P is the starting principal, or amount borrowed, in dollars.
• r is the monthly interest rate as a decimal: APR ÷ 1200 when APR is entered as a percentage per year.
• n is the number of monthly payments: loan term in years × 12.

The calculator rounds the payment to cents, then estimates total interest as PMT × n − P. Using the rounded payment in that calculation makes the displayed total consistent with the monthly amount shown. Actual final payments can differ slightly if a lender adjusts the last installment or uses different rounding.

Worked Example

With the calculator’s default inputs—$20,000 principal, 8% APR, and a 5-year term—the calculation is:

1. Convert APR to a monthly decimal rate: 8 ÷ 1200 = 0.0066667.
2. Count the payments: 5 × 12 = 60.
3. Substitute into the payment formula: $20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻⁶⁰].
4. Round the calculated installment to cents: $405.53 per month.
5. Multiply that rounded payment by 60: $405.53 × 60 = $24,331.80 in scheduled payments.
6. Subtract the original principal: $24,331.80 − $20,000 = $4,331.80 estimated total interest.

Assumptions

• The interest rate is fixed for the whole repayment term.
• Payments are equal, made monthly, and paid at the end of each monthly period.
• Interest compounds monthly at APR divided by 12.
• The estimate excludes fees, taxes, insurance, PMI, escrow, and any charges not entered as inputs.

How Equity Loan Payments Work

A home equity loan generally means borrowing a set amount against home equity and repaying it through scheduled installments. In the basic fixed-payment model, each payment covers interest accrued since the prior payment and reduces principal. Early installments include a larger interest share; as the balance falls, the interest portion generally shrinks and more of each level payment goes toward principal.

“Equity loan” is sometimes used loosely. A closed-end home equity loan with a fixed balance can be estimated with the formula above. A HELOC is revolving credit: the borrower may draw funds over time, the balance can change, and its rate or payment structure may vary. A single fixed-payment calculation cannot fully represent those moving parts. Use the loan’s disclosed payment terms for a more specific estimate.

How to Use and Interpret the Calculator

• Loan amount: Enter the amount actually borrowed, not the home’s value or available equity. If financed charges are included in the principal, use the resulting loan amount.
• APR: Enter the annual percentage rate as a percentage, such as 8 for 8%, rather than 0.08. The formula converts it to a monthly rate.
• Term: Enter the repayment period in years. The calculator converts years to monthly installments.

The first result is the estimated monthly principal-and-interest payment. The second is estimated interest paid across all scheduled installments, assuming the payment is made as calculated and the loan runs to the end of its term. It does not mean the full monthly housing cost: other bills or charges may apply independently. A longer term usually spreads principal repayment across more installments, while a changed APR or principal changes the calculated payment; the calculator does not determine whether a loan is suitable or whether an applicant qualifies.

Common Errors and Formula Limits

A frequent mistake is dividing APR by 100 but forgetting to divide by 12 as well. The formula needs a monthly decimal rate, so an 8% APR becomes 0.08 ÷ 12, or 0.0066667. Another mistake is entering a term in months in a field that expects years: entering 60 here would mean 60 years, not 60 monthly payments.

The calculation is an estimate rather than a full loan statement. It assumes regular monthly periods and a constant rate; it does not model variable rates, irregular payment dates, skipped payments, extra principal payments, draw periods, or payoff fees. It also does not establish the actual APR or fees. Obtain the applicable rate, payment schedule, and charges from the lender’s disclosure, then use the figures that match the loan being considered. This is educational estimate arithmetic, not financial advice.

Frequently Asked Questions

How do I calculate the monthly payment on an equity loan?
Convert APR to a monthly decimal by dividing the percentage by 1200, convert years to months, and apply PMT = P × r ÷ [1 − (1 + r)⁻ⁿ]. Round the result to cents for an estimate.

Is an equity loan payment the same as a HELOC payment?
Not necessarily. This formula assumes a fixed starting balance, fixed rate, and level monthly payments. A HELOC can have changing draws, balances, rates, or payment terms, so its actual payment calculation may differ.

Does the monthly payment include taxes and insurance?
No. The calculator estimates principal and interest only. It does not include taxes, insurance, escrow, PMI, or lender charges unless those costs are separately included in the amount being analyzed.

Why is the calculator’s total interest based on a rounded payment?
Payments are normally expressed in cents. Multiplying the displayed cent-rounded payment by the number of installments keeps the estimated total payments and interest aligned with the payment shown, though a lender’s final installment may differ.

Can I use this formula for a variable-rate equity loan?
It can estimate payments for one assumed rate and term, but it cannot forecast a rate that changes. Recalculate with a new rate for a simplified scenario, and consult the lender’s payment terms for the actual method.

The result is an estimate, and the lender’s disclosure gives the exact figures.

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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