San Diego 30-Year Refinance Rate Calculator

This calculator estimates the monthly principal-and-interest payment and total interest for a 30-year mortgage refinance using the loan amount and annual interest rate you enter. It does not show a live San Diego market quote: refinance rates change, and you must obtain the actual rate and costs from a lender to make a personalized estimate.

Formula

The calculator uses the standard fixed-rate, fully amortizing loan payment formula. It calculates the payment as M = P × r ÷ [1 − (1 + r)⁻ⁿ], then rounds the monthly payment to the nearest cent. Here, M is monthly principal and interest in dollars, P is the new refinance loan amount in dollars, r is the monthly interest rate as a decimal (annual APR ÷ 12 ÷ 100), and n is the number of monthly payments (years × 12). Total interest is calculated as the rounded monthly payment × number of payments − loan amount.

For the default APR of 6.5%, the monthly rate is 0.065 ÷ 12, or approximately 0.0054167. A 30-year term has 360 payments. The APR is an input for illustration, not a current San Diego rate or an offer. If a lender quotes a rate separately from APR, check which figure is appropriate for the comparison and how the lender defines it.

Worked Example

Using exactly the defaults above: loan amount P = $500,000, APR = 6.5%, and term = 30 years.

1. Convert the annual rate to a monthly decimal: r = 6.5 ÷ 1,200 = 0.0054166667.
2. Find the number of payments: n = 30 × 12 = 360.
3. Substitute into the payment formula: M = 500,000 × 0.0054166667 ÷ [1 − (1.0054166667)⁻³⁶⁰].
4. Round the result to cents: estimated monthly principal-and-interest payment = $3,160.34.
5. Calculate total interest using the rounded payment: $3,160.34 × 360 − $500,000 = $637,722.40.

The payment is not the full monthly housing expense. Property taxes, homeowners insurance, mortgage insurance if applicable, and any escrowed charges are not included. The calculation also does not add closing costs to the loan amount unless you include them in the amount entered.

Assumptions

• The interest rate stays fixed for the full entered term.
• Payments are equal, made monthly, and paid at the end of each monthly period.
• Interest accrues monthly using the annual rate divided by 12; the formula assumes monthly amortization.
• Fees, taxes, insurance, mortgage insurance, escrow, and any lender-specific charges are excluded.

What a San Diego Refinance Rate Means

A refinance replaces an existing mortgage with a new loan. The new loan’s rate is only one part of its cost: the amount borrowed, term, fees, and how long you keep the loan also matter. There is no single rate that applies to every San Diego homeowner. A quoted rate can depend on loan details and the borrower’s application, and rates can change over time. This page does not report or predict current market rates.

To use the calculator, enter the proposed new loan amount rather than automatically entering the home’s value. A refinance amount may reflect the remaining mortgage balance and, depending on the transaction, costs or other borrowing. Ask the lender for a written estimate of the rate, APR, payment, and closing costs for the specific loan being considered.

How to Compare Refinance Estimates

For a meaningful comparison, use the same loan amount and term in each calculation, and enter the rate associated with each written quote. Then review items the calculator omits. In particular, distinguish the scheduled principal-and-interest payment from an all-in housing payment, and check whether fees are paid upfront or financed into the new balance.

• Rate and APR: Ask how each is defined in the quote and what costs are reflected in the APR.
• Loan amount: Confirm whether costs are included in the amount borrowed.
• Term: A longer term spreads payments over more months; it can lower the scheduled payment while increasing total interest under the same assumptions.
• Costs and timing: Compare the estimated charges and consider how long you expect to keep the new loan. This calculator does not calculate a break-even date.
• Loan structure: Confirm whether the quoted rate is fixed for the entire term and whether there are special payment features not represented here.

For example, two estimates might show the same monthly principal-and-interest payment but differ in upfront charges, financed costs, or term. The payment alone therefore does not establish which offer has lower overall cost. To estimate a break-even period, the relevant figures include the actual refinance costs and the change in comparable monthly expenses; taxes, insurance, and changing balances may also affect a real-world comparison.

Common Limits and Mistakes

A frequent mistake is treating the displayed payment as a lender quote. It is only the result of the inputs and formula. Another is entering a home’s market value instead of the proposed loan amount, or comparing a 30-year estimate with an existing loan that has fewer years remaining without accounting for the longer repayment period.

Rounding also matters. This calculator rounds the monthly payment to cents before multiplying by the number of payments to estimate total interest, so a calculation using an unrounded payment may differ slightly. Actual loan schedules can also differ because of lender rounding, payment dates, fees, escrow, and the precise terms in the disclosure. The formula assumes a constant rate and regular payments; it does not model an adjustable rate, missed or extra payments, cash taken out, or a changing balance.

Frequently Asked Questions

What is the current 30-year refinance rate in San Diego?
This calculator does not provide live rates. Rates vary and can change; request a current, individualized quote and written loan-cost details from a lender.

How much is a $500,000 refinance payment for 30 years?
At the calculator’s illustrative 6.5% APR input, the estimated monthly principal-and-interest payment is $3,160.34. This is not a market quote and excludes taxes, insurance, and fees.

Does a 30-year refinance payment include property taxes and insurance?
No. The result covers principal and interest only. Taxes, homeowners insurance, mortgage insurance, escrow, and other charges are not included.

Is APR the same as the interest rate?
They are related but not necessarily identical. The APR may reflect certain loan costs as well as interest, depending on the quote and applicable calculation. Ask the lender to explain both figures and which one to use when comparing estimates.

Does refinancing restart the 30-year clock?
A new 30-year loan has 360 scheduled monthly payments from its start. Whether that extends repayment compared with an existing mortgage depends on how much time remains on the current loan.

Does this calculator include refinance closing costs?
No. You can include costs in the entered loan amount only if they will be financed, but the calculator does not itemize or estimate them. Get the actual charges from the lender’s written disclosure.

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

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in p | New loan amount | $ | 500000 | 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 | $ | pmt * yrs * 12 - p | 2