15-Year Fixed Refinance Rates and Payment Calculator

A 15-year fixed refinance rate is the annual interest rate a lender offers for replacing an existing mortgage with a new loan repaid over 15 years, with the rate held constant during the loan term. Use the calculator below to estimate principal-and-interest payments from a loan amount and APR; it does not look up live refinance rates or include closing costs.

Formula

The calculator uses the standard fixed-payment amortization formula. Monthly payment = principal × monthly rate ÷ [1 − (1 + monthly rate)^{−number of payments}]. In symbols: M = P × r / [1 − (1 + r)⁻ⁿ].

• P is the new mortgage principal, in dollars.
• APR is the annual percentage rate entered as a percent per year.
• r is the monthly rate, calculated as APR ÷ 1,200.
• n is the number of monthly payments: loan term in years × 12.
• M is the estimated monthly principal-and-interest payment, in dollars.

Total interest is calculated as the rounded monthly payment multiplied by the number of payments, minus the original principal. The APR is an input, not a rate quote. Ask a lender for the rate and loan terms that apply to a specific application.

Worked Example

Using the defaults—$200,000 principal, 6.5% APR, and 15 years—the monthly rate is 0.065 ÷ 12 = 0.005416667, and the number of payments is 15 × 12 = 180.

Monthly payment = 200,000 × 0.005416667 ÷ [1 − (1.005416667)⁻¹⁸⁰] = $1,742.21 when rounded to cents. Total of payments = $1,742.21 × 180 = $313,597.80. Estimated total interest = $313,597.80 − $200,000 = $113,597.80.

Assumptions

• The interest rate remains fixed for the entire term.
• Payments are level monthly payments, made at the end of each monthly period.
• Interest is modelled monthly using APR ÷ 12.
• The estimate excludes lender fees, closing costs, taxes, homeowners insurance, mortgage insurance, and escrow.

What a 15-Year Fixed Refinance Rate Means

Refinancing replaces an existing mortgage with a new mortgage. The new loan may have a different balance, interest rate, term, or payment structure. With a fixed-rate 15-year loan, the scheduled principal-and-interest payment is generally level for the loan’s life, assuming the borrower makes payments as scheduled and there are no changes to the loan balance or terms.

A 15-year term means 180 scheduled monthly payments. Compared with a longer term at the same rate and principal, the shorter term generally produces a higher monthly principal-and-interest payment because the balance is repaid in fewer months. It can also produce less total interest under those same assumptions. Actual comparisons require the offered rates, fees, new principal, and remaining time on the current loan; none can be inferred from the term alone.

How to Interpret the Estimate

The payment shown is not the full housing payment. A mortgage bill may also include property taxes, insurance, mortgage insurance, or escrowed amounts, depending on the loan and billing arrangement. The estimate also does not say how much cash may be needed at closing or whether costs are paid upfront or added to the new balance.

For a meaningful comparison, gather the same details for both the current mortgage and the proposed refinance:

• Current principal balance and remaining term.
• Proposed new loan amount, including any costs rolled into the balance.
• Quoted APR and whether the rate is fixed for the full term.
• Itemized lender and third-party charges, plus any credits.
• Estimated monthly principal, interest, taxes, insurance, and mortgage insurance where applicable.

APR and interest rate are related but not interchangeable in every quote. APR may reflect certain finance charges as well as interest, while the note rate is the rate used to calculate scheduled interest. Check the lender’s disclosures to understand which rate is being quoted and what charges are included.

Costs, Comparisons, and Common Issues

A lower payment by itself does not establish that refinancing reduces the overall cost. The payment could fall because the new loan stretches repayment over more years, even if fees are added or total interest rises. Conversely, a 15-year loan may have a higher monthly payment than a longer-term option while paying down principal faster. Compare total payments and charges over a time period that fits the actual plans being considered, not just the monthly figure.

One common misconception is that a 15-year refinance automatically saves money because it has fewer payments. The outcome depends on the new loan’s rate, principal, fees, and the costs and remaining term of the mortgage being replaced. If closing costs are added to the loan, the new principal increases and so can the payment and interest. If costs are paid separately, they still matter to the total cost of the transaction.

Other limitations to keep in mind:

• The calculator assumes a fully amortizing loan with a constant rate and equal monthly payments.
• It does not model adjustable rates, skipped or extra payments, payment changes, balloon balances, or a payoff before the end of the term.
• The displayed total interest uses a payment rounded to the nearest cent, so a real lender’s final payment schedule may differ slightly because of rounding and servicing details.
• Entering a hypothetical APR provides a mathematical estimate only; it does not indicate the rate available to any borrower.

Frequently Asked Questions

What is a 15-year fixed refinance rate?
A 15-year fixed refinance rate is the annual interest rate on a replacement mortgage with a 15-year repayment term, where the rate is fixed for that term. A lender must provide the applicable quote; this calculator does not retrieve live rates.

How do I calculate a 15-year refinance payment?
Enter the proposed loan principal and annual APR. The formula converts APR to a monthly rate and applies it over 180 payments for a 15-year term. The result estimates principal and interest, not the complete housing payment.

Does a 15-year refinance always have a lower rate?
No conclusion about a particular quote follows from the term alone. Rates vary by lender, borrower, loan details, and market conditions. Compare actual written loan estimates rather than assuming one term will have a lower rate.

Will refinancing to 15 years reduce total interest?
It can reduce total interest when the relevant principal, rate, fees, and repayment conditions support that outcome, but it is not automatic. A shorter term usually means a higher scheduled principal-and-interest payment than a longer term for the same principal and rate.

Are closing costs included in this calculator?
No. The calculator includes only principal and interest under its fixed-rate assumptions. Obtain the lender’s itemized fees and determine whether any costs are paid upfront or included in the new loan balance.

This result is an estimate; the lender’s disclosure gives the exact figures.

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in p | New loan amount | $ | 200000 | 1 | 100000000
in apr | Interest rate (APR) | % | 6.5 | 0.01 | 100
in yrs | Loan term | years | 15 | 0.0833 | 50
out pmt | Monthly principal and interest | $ | p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2