Equity Loan Interest: Calculate Payments and Total Cost

An equity loan’s interest is the cost of borrowing against the equity in an asset, commonly a home; the exact amount depends on the loan balance, annual rate, and repayment schedule. Use this calculator to estimate a fixed-rate loan’s monthly payment and total interest: enter the amount borrowed, APR, and term.

Formula

The calculator treats the loan as a fixed-rate balance repaid through equal monthly payments. It first calculates the payment using the standard amortizing-loan formula, rounds that payment to the nearest cent, and then subtracts the amount borrowed from all scheduled payments to estimate total interest.

• Monthly payment: M = round[P × r ÷ (1 − (1 + r)⁻ⁿ), 2]
• Total interest: I = M × n − P
• Monthly rate: r = APR ÷ 1,200

Here, P is the principal, or loan amount, in dollars; APR is the annual percentage rate entered as a percentage; r is the monthly rate as a decimal; n is the number of monthly payments (term in years × 12); M is the monthly payment in dollars; and I is estimated total interest in dollars. The APR is divided by 1,200 to convert a percentage per year to a monthly decimal rate. The formula assumes no additional fees are financed into the balance.

Worked Example

Using the calculator’s defaults—$20,000 borrowed, 8% APR, and a five-year term:

1. Convert the annual rate to a monthly decimal: r = 8 ÷ 1,200 = 0.0066667.
2. Convert the term to payments: n = 5 × 12 = 60 months.
3. Calculate the payment: M = round[20,000 × 0.0066667 ÷ (1 − (1 + 0.0066667)⁻⁶⁰), 2] = $405.53 per month.
4. Calculate total interest using the rounded payment: I = $405.53 × 60 − $20,000 = $4,331.80.

These amounts are estimates from the stated formula. The final payment on a real loan can differ because of the lender’s rounding and payment schedule.

Assumptions

• The interest rate is fixed for the full term.
• Payments are equal, made monthly, and begin one month after the loan is issued.
• Interest is modelled monthly at APR ÷ 12.
• Fees, taxes, insurance, property costs, and any escrow or mortgage-insurance amounts are not included.

What Equity Loan Interest Means

Equity is the value of an asset minus the debt secured by it. In a home-equity loan, for example, the home is collateral and the loan is generally a separate amount borrowed against available home equity. The calculator does not estimate how much equity a person has or how much a lender might offer; those figures depend on information and terms that must be obtained from the relevant lender.

Interest is the charge for borrowing the principal. At the start of a typical amortizing loan, part of each payment covers interest accrued on the outstanding balance, and the rest reduces principal. As the balance falls, the interest portion generally declines and more of each level payment goes toward principal. This is why multiplying the original principal by the APR and term is not an accurate way to find the interest on a normally amortizing loan.

“Equity loan” can refer to different products. A lump-sum home-equity loan commonly has a repayment schedule, while a home-equity line of credit allows borrowing and repayment under a revolving arrangement and may have a variable rate. This calculator models neither changing rates nor changing withdrawals: it is for a single advance repaid in equal monthly instalments at a fixed rate.

How to Use and Interpret the Estimate

Enter the amount actually borrowed, the APR quoted for that loan, and the repayment term. The APR and term should correspond to the same offer. If fees are added to the loan balance, include them in the principal only if you want to estimate payments on that larger balance; the calculator cannot separate principal from financed charges.

The monthly-payment result is the scheduled amount under the model. Total interest is that rounded payment multiplied by the number of scheduled months, minus the original loan amount. It is not the total amount paid: the estimated total of payments is principal plus interest. For the example, that is $24,331.80 before any charges excluded by the assumptions.

Changing the inputs helps show how loan structure affects the arithmetic. For a fixed principal and rate, a longer term usually lowers the scheduled monthly payment but increases the number of payments, which can increase total interest. A higher rate generally increases both the payment and the interest cost. These are mathematical effects, not a prediction of any lender’s offer or a recommendation about which loan to take.

Common Sources of Differences

• Confusing APR with a monthly rate: Enter the annual APR as a percentage, such as 8, not 0.08 or 8 divided by 12. The formula performs the conversion.
• Ignoring payment rounding: This calculator rounds the monthly payment to cents before calculating total interest. A lender may adjust the final payment to clear a remaining balance.
• Leaving out charges: Fees, insurance, taxes, and other costs are not represented. A quoted payment can therefore be different from this estimate.
• Assuming a variable rate stays fixed: If a rate changes, the payment or payoff path may change too. A single fixed APR cannot reproduce that schedule.
• Using a line of credit like a lump-sum loan: Draws, repayments, and rate changes can vary over time, so this amortization calculation does not model a revolving balance.

Frequently Asked Questions

How do you calculate interest on an equity loan?
For a fixed-rate amortizing loan, calculate the monthly payment from the principal, monthly rate, and number of payments. Multiply that payment by the number of payments and subtract the principal to estimate total interest, as this calculator does.

Is equity loan interest the same as the APR?
No. APR is an annual rate used to express borrowing costs under the loan’s terms; total interest is the dollar amount accumulated across repayment. This calculator uses the entered APR as its interest-rate input but does not add fees or other costs to the result.

Does a longer term reduce equity-loan interest?
A longer term usually spreads repayment over more months and can reduce the monthly payment, but it may increase total interest because the balance is repaid over a longer period. The calculator compares only the inputs entered and does not assess an offer.

Does this calculator work for a home-equity line of credit?
Not accurately when the balance, rate, or payments vary. It assumes one initial loan amount, a fixed APR, and equal monthly payments throughout the term.

Why does a lender’s payment differ from this estimate?
The lender may use a different rate, term, balance, payment date, rounding convention, or treatment of fees. Check the lender’s loan disclosure for the figures and schedule that apply to the specific loan.

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

Related

• Personal Loan Refinance Calculator: Compare Payments
• Personal Loan Refinance Calculator and Rate Guide
• Loan Refinance vs. Consolidation: Key Differences

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