How to Use This Calculator

Enter your home price (or target purchase price), your planned down payment percentage, your current mortgage rate if you already have a loan, and your loan term. The calculator fetches today's live average 30-year fixed mortgage rate and compares your monthly payment at that rate against your current rate.

If the live rate is lower than what you entered as your current rate, the calculator estimates your potential lifetime savings from refinancing. If it isn't, it tells you directly that your existing rate is already competitive rather than showing a misleading negative number.

What the Inputs Mean

  • Home Price: The purchase price or current value of the home, before your down payment is subtracted.
  • Down Payment: The percentage of the home price you're putting down — the rest is financed as your loan amount.
  • Your Current Rate: The mortgage rate you currently have (or expect to be quoted), compared against today's live average rate.
  • Term: Your loan's repayment period in years — 30 and 15 years are the most common.

Assumptions & Formula

  • The live rate is the national average 30-year fixed mortgage rate reported by Freddie Mac's Primary Mortgage Market Survey, published via the Federal Reserve Economic Data (FRED) series MORTGAGE30US. Your actual quoted rate will vary based on your credit profile, loan size, property type, and lender.
  • The refinance savings estimate compares your current rate's monthly payment against the live rate's monthly payment, multiplied across the full remaining term — it does not subtract closing costs, which typically range from 2–5% of the loan amount and should be weighed against any projected savings.
  • This calculator assumes a standard fixed-rate, fully amortizing loan and does not account for property tax, homeowners insurance, or PMI, which are commonly bundled into a real mortgage payment.

Formula: Monthly payment = L × [r(1+r)ⁿ] ÷ [(1+r)ⁿ − 1], where L is the loan amount (home price minus down payment), r is the monthly rate, and n is the number of monthly payments. Lifetime refi savings = (payment at current rate − payment at live rate) × total number of payments.

Worked Example

A $400,000 home with 20% down ($80,000) finances $320,000. At a current rate of 7.25% over 30 years, the monthly payment is about $2,183. If today's live 30-year average rate is 6.42%, the payment at that rate is about $2,008 — a monthly savings of roughly $175, or about $63,000 over the full 30-year term before accounting for closing costs. If your current rate is already at or below the live rate, the calculator will say so rather than showing a false savings figure.

Frequently Asked Questions

Where does the live rate come from, and how current is it?

It's pulled directly from the Federal Reserve Economic Data (FRED) series MORTGAGE30US, which reports Freddie Mac's weekly Primary Mortgage Market Survey average. The page shows the live rate as fetched; see the Sources section below for the exact as-of date of the underlying data.

Does this account for refinance closing costs?

No — the savings estimate is based purely on the monthly payment difference across your full term. Refinance closing costs typically run 2–5% of the loan amount, so compare that cost against the projected savings and your break-even timeline before deciding.

Why is the live rate different from what my lender quoted me?

FRED's rate is a national weekly average. Individual lenders price based on your specific credit score, loan-to-value ratio, loan size, property type, and points paid, so your personal quote will differ from the national average in either direction.

Does a lower rate always mean I should refinance?

Not necessarily — you need to weigh the monthly and lifetime savings against closing costs and how long you plan to stay in the home. A mortgage professional can help calculate your specific break-even point.

Sources