Fixed-Rate Mortgage Calculator

About the Fixed-Rate Mortgage Calculator

A fixed-rate mortgage locks in your interest rate for the entire life of the loan, so the principal and interest payment does not change once the loan closes. That predictability is why fixed-rate mortgages remain one of the most common mortgage structures in the United States.

This fixed-rate mortgage calculator lets you enter a loan amount, annual interest rate, and term length to estimate your monthly payment, total interest over the life of the loan, and a year-by-year amortization breakdown. Whether you are comparing a 15-year term against a 30-year term or shopping rates from multiple lenders, the worksheet gives you a consistent way to compare scenarios.

Understanding the math behind a fixed-rate mortgage is straightforward: the standard amortization formula produces the same payment every month for the full term. The mix of interest and principal changes over time, with early payments leaning toward interest and later payments leaning toward principal.

When This Page Helps

Before committing to a mortgage, it helps to see exactly what you will pay each month and over the full term. This calculator helps you compare scenarios in seconds — change the rate by 0.25% or shorten the term by five years and see the impact on your monthly outlay and lifetime interest cost.

Borrowers, agents, and loan officers use fixed-rate payment calculations to set budgets, compare lender quotes, and evaluate whether a specific term fits the plan.

How to Use the Inputs

1. Enter your total loan amount — the purchase price minus your down payment.
2. Enter the annual fixed interest rate quoted by your lender (e.g., 6.50%).
3. Select a loan term: 10, 15, 20, 25, or 30 years.
4. Review your fixed monthly principal and interest payment.
5. Check total interest paid over the life of the loan.
6. Toggle the amortization schedule to see how each year's payments split between principal and interest.

Example Calculation

Tips & Best Practices

• Lock your rate as soon as you are under contract — fixed rates can move daily.
• Even a 0.125% rate reduction saves thousands over 30 years; always negotiate.
• Choose the shortest term you can comfortably afford to minimize total interest.
• Verify that "fixed rate" means fixed for the full term, not just an introductory period.
• Budget for taxes, insurance, and possible PMI on top of the P&I payment shown here.
• If rates drop after closing, you can refinance — but factor in closing costs.

How Amortization Works on a Fixed-Rate Mortgage

Every fixed monthly payment contains two portions: interest on the current balance and principal reduction. In the first year of a 30-year, $320,000 loan at 6.5%, roughly $20,600 of your payments goes to interest and only $3,680 to principal. By year 15 the split is nearly even, and in the final year almost every dollar goes to principal. This gradual shift is called the amortization curve.

Fixed Rate vs. Adjustable Rate — A Deeper Look

A fixed-rate mortgage offers predictable payments for the life of the loan, which simplifies long-term budgeting. An adjustable-rate mortgage (ARM) starts with a lower teaser rate that resets periodically — typically after 5 or 7 years. If you expect to sell before the first adjustment, an ARM could save money; otherwise the fixed rate provides insurance against rising rates.

When to Consider Shorter Terms

A 15-year fixed mortgage often carries a rate 0.5–0.75% lower than a 30-year and saves more than half the total interest. The trade-off is higher monthly payments. Many financial advisors suggest choosing the 15-year if the payment is no more than 25% of your gross income, and using a 30-year if you need cash-flow flexibility.

Frequently Asked Questions

• What does "fixed rate" mean on a mortgage?

  A fixed-rate mortgage means the interest rate stays the same for the entire loan term — whether that is 10, 15, 20, or 30 years. Your monthly principal and interest payment is set at closing and never changes, regardless of market rate movements.

• Is a 15-year or 30-year fixed rate better?

  A 15-year term has higher monthly payments but a lower interest rate and dramatically less total interest — often less than half. A 30-year term offers lower monthly payments and more cash-flow flexibility. Choose based on your budget and financial goals.

• How is the monthly payment calculated?

  The standard amortization formula multiplies the principal by a factor that accounts for the monthly interest rate and total number of payments. The result is a level payment that covers interest on the declining balance plus a portion of principal each month.

• Why do early payments have more interest?

  Interest is charged on the outstanding balance. In the beginning the balance is at its highest, so most of each payment covers interest. As the balance decreases, more of each payment goes toward principal. This is called amortization.

• Can I pay off a fixed-rate mortgage early?

  Yes. Most conventional fixed-rate mortgages allow prepayment without penalty. Making extra payments reduces your principal faster, which decreases total interest and shortens the payoff timeline.

• Does this calculator include taxes and insurance?

  No. This calculator shows only principal and interest (P&I). Your full monthly housing cost (PITI) also includes property taxes, homeowners insurance, and possibly PMI. Budget an additional 20-40% above P&I for these items.

• What is a good fixed mortgage rate?

  Rates vary with market conditions, your credit score, and down payment size. As of early 2026, average 30-year fixed rates hover around 6-7%. Excellent credit and a 20% down payment typically secure the best available rate.

• Fixed rate vs adjustable rate — which should I choose?

  Choose a fixed rate if you plan to stay in the home long-term and want payment certainty. An adjustable rate (ARM) can offer a lower initial rate, making it attractive if you plan to sell or refinance within the introductory period.