An NJ refinance calculator estimates a new monthly principal-and-interest payment from the loan amount, annual percentage rate (APR), and term you enter. It can also show total interest over the term; use a lender’s actual loan offer for the APR and amount, because this estimate does not look up New Jersey rates.
Formula
The calculator uses the standard fixed-rate amortizing-loan payment formula. It first converts the annual APR to a monthly rate, then calculates the level payment that pays interest and principal across the selected number of monthly payments:
Monthly payment = P × r ÷ [1 − (1 + r)−n]
- P is the new loan principal, in dollars.
- r is the monthly interest rate, calculated as APR ÷ 1,200. For example, 6.5% APR gives 0.065 ÷ 12, or about 0.0054167 per month.
- n is the number of monthly payments, calculated as years × 12.
The payment is rounded to the nearest cent. Total interest is then estimated as the rounded monthly payment multiplied by the number of payments, minus the principal: total interest = payment × n − P. This convention makes the displayed total follow the displayed payment; a lender’s final schedule may differ slightly because of its exact payment dates, rounding, and closing details.
Worked Example
Using the calculator’s default inputs—$300,000 principal, 6.5% APR, and a 30-year term:
- Monthly rate: 0.065 ÷ 12 = 0.0054166667.
- Number of payments: 30 × 12 = 360.
- Substitute into the payment formula: $300,000 × 0.0054166667 ÷ [1 − (1.0054166667)−360].
- The monthly principal-and-interest payment rounds to $1,896.20.
- Total interest using the rounded payment: $1,896.20 × 360 − $300,000 = $382,632.00.
Assumptions
- The interest rate is fixed for the entire selected term.
- Payments are equal, monthly payments made at the end of each period.
- Interest compounds monthly using APR ÷ 12.
- The calculation excludes lender fees, taxes, homeowners insurance, mortgage insurance, escrow, and other costs unless included in the loan amount you enter.
What the Estimate Means for a New Jersey Refinance
“Refinance rates in NJ calculator” can refer to two different things: a tool that estimates payments after you supply a rate, or a live rate comparison. This page does the first. It does not retrieve current offers or determine a rate for a particular borrower. Rates and costs depend on the details of a loan offer and borrower, so enter the APR and proposed amount shown in the lender’s written disclosure rather than treating the example defaults as market quotes.
The principal entered should represent the new mortgage balance being financed, not necessarily the home’s value or the balance on an old statement. A refinance may involve paying off the existing mortgage and financing permitted closing charges; if costs are paid separately, they are not part of the principal in this calculator. If costs are added to the new loan, include them in the amount entered to see their payment effect. The resulting estimate is not a payoff quote and does not establish the cash needed at closing.
How to Use the Calculator and Compare Offers
- Enter the proposed new loan amount. Use the principal the lender is evaluating, including any costs that are actually financed.
- Enter the quoted APR. Use the APR supplied for the offer and make sure you are comparing the same type of rate and loan structure.
- Enter the term in years. A shorter term generally means fewer payments and a different monthly payment; compare only terms that are actually offered.
- Review both outputs. The payment covers principal and interest only. Total interest is an arithmetic estimate for the full term, assuming every payment is made as scheduled.
For a fair comparison, calculate the proposed loan and the remaining existing loan separately using their respective balances, rates, and remaining terms. A lower monthly payment by itself does not show whether the transaction reduces total costs: a new longer term can spread repayment over more months. For a broader comparison, also obtain itemized closing costs and ask how points, prepaid items, and any financed fees are treated. Those figures are not included in this calculator’s total-interest output.
Costs, Limits, and Common Mistakes
The APR is not the same as the monthly rate. The calculator divides the annual percentage by 1,200; entering 0.065 when you mean 6.5% would make the assumed rate far too small. Enter 6.5 for 6.5% APR. Likewise, enter a term in years, not months: a 30-year term is 30, which the formula converts to 360 payments.
This calculation isolates scheduled principal and interest. It does not include property taxes, homeowners insurance, mortgage insurance, escrow deposits, lender charges, or changes in those costs. It also assumes a fixed rate, so it does not model an adjustable-rate loan, skipped or extra payments, a payoff before the end of the term, or a changing balance from other transactions. The total-interest figure is not the same as total cash paid to refinance, since it omits upfront and ongoing costs outside the loan payment.
Another common misunderstanding is that a calculator can tell you what rate you qualify for. It cannot: the APR is an input, not a result. Request the actual figures and payment schedule for the specific transaction, and check that the quoted amount, term, rate type, and included costs match the assumptions you want to evaluate.
Frequently Asked Questions
Does this calculator show current New Jersey refinance rates?
No. It calculates a payment from an APR you provide. Obtain a current, transaction-specific quote from a lender and use that disclosed APR as the input.
What rate should I enter?
Enter the APR in the written offer you are evaluating, expressed as a percentage—for example, enter 6.5 for 6.5%. The default is only a worked-example assumption, not a statement about available rates.
Does the monthly payment include taxes and insurance?
No. The output is principal and interest only. Taxes, homeowners insurance, mortgage insurance, escrow, and loan costs are not included unless you separately account for them outside this estimate.
Should I add closing costs to the loan amount?
Only if those costs are included in the proposed new principal. For costs paid separately, leave them out of the loan amount and consider them separately when comparing the transaction.
Why can a refinance lower the payment but increase total interest?
A longer repayment term can reduce the amount due each month while extending the time interest accrues. Compare the payment, remaining term, total interest estimate, and separately disclosed costs rather than relying on the payment alone.
This result is an estimate; the lender’s disclosure gives the exact figures.
Related
Formula used
in p | New loan amount | $ | 300000 | 1 | 100000000 in apr | Interest rate (APR) | % | 6.5 | 0.01 | 100 in yrs | Loan term | years | 30 | 0.0833 | 50 out pmt | Monthly principal-and-interest payment | $ | round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) | 2 out int | Total interest over term | $ | pmt * yrs * 12 - p | 2
Each line is one input (in, sel, list) or one result (out: label, unit, formula, decimals). How the calculators work
Method: the standard loan formula for this calculation, fixed rate and monthly compounding unless stated, rounded as each result states. Not financial advice; no lender, rate or product is recommended. See formulas and assumptions, the disclaimer or report an error.
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