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Refinance Amortization Calculator

Generate a full year-by-year amortization schedule showing how each payment splits between principal and interest over the life of your loan.

Generate Your Amortization Schedule

Enter your loan details to see the complete breakdown of principal paid, interest paid, and remaining balance for each year of your mortgage.

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What Is Amortization?

Amortization is the process of paying off a loan through regular scheduled payments over a fixed period. Each payment consists of two components: interest charged on the outstanding loan balance, and principal that reduces what you owe. Because the balance decreases with each payment, the interest component of each payment shrinks over time, and the principal component grows — even though the total payment remains exactly the same every month.

This means that in the early years of your mortgage, most of your payment is effectively rent paid to the lender for the use of the borrowed money. In the later years, most of your payment is actually building equity. Understanding this dynamic is essential for making smart decisions about refinancing, extra payments, and loan terms.

How to Use This Calculator

  1. Loan Amount: Enter the principal balance of your new refinanced loan. This is the amount you will borrow, not including any costs rolled into the loan unless you are financing them.
  2. Annual Interest Rate: Enter the interest rate on your new loan as a percentage. For example, type 6.75 for a 6.75% rate. Be sure this is the interest rate, not the APR (which includes fees).
  3. Loan Term: Select the loan term — 10, 15, 20, 25, or 30 years. Shorter terms have higher monthly payments but dramatically lower total interest paid.
  4. Click Generate Schedule to see your monthly payment, total interest, and the full year-by-year amortization table.

Run the calculator multiple times with different term options — 15 years vs. 30 years, or 20 years vs. 25 years — to compare how the term choice affects your total interest cost and monthly payment.

The Amortization Formula

Monthly Payment = P × [r(1+r)^n] / [(1+r)^n − 1]

Each month: Interest Portion = Remaining Balance × Monthly Rate
               Principal Portion = Monthly Payment − Interest Portion
               New Balance = Prior Balance − Principal Portion
Where P = loan principal, r = monthly interest rate (annual rate ÷ 12), n = total months

This formula produces a fixed payment amount. What changes each month is how that fixed payment is divided between interest and principal. As the balance falls, less interest accrues, and more of the fixed payment goes to principal. This is the core mechanic of mortgage amortization.

The Interest Front-Loading Effect Explained

One of the most important — and often surprising — facts about mortgage amortization is how dramatically interest-heavy the early payments are. Most borrowers are surprised to learn how little equity they build through payments alone in the first years of a 30-year mortgage.

A Concrete Breakdown

Consider a $300,000 loan at 6.5% for 30 years. The monthly payment is approximately $1,896.

  • Payment 1: Interest = $300,000 × (6.5% ÷ 12) = $1,625. Principal = $271. Balance: $299,729.
  • Payment 12 (end of Year 1): Balance has dropped to about $296,600. Total paid in Year 1: $22,752. Total principal paid: $3,400. Total interest paid: $19,352. You paid 85% in interest.
  • Payment 60 (end of Year 5): Balance: approximately $280,000. In 5 years, amortization alone reduced the balance by $20,000 on a $300,000 loan.
  • Payment 180 (end of Year 15): Balance: approximately $213,000. Interest portion of each payment: approximately $1,154. Principal portion: $742.
  • Payment 300 (end of Year 25): Balance: approximately $105,000. Interest portion: approximately $569. Principal portion: $1,327. Now more than half of each payment goes to principal.

Over the full 30-year life of this loan, you'll pay $300,000 in principal plus approximately $382,600 in interest — for a total of $682,600 paid on a $300,000 loan. That's more than double the original amount.

Real-World Example: Amy's Refinance

Amy refinances $340,000 at 6.25% for 30 years. Her monthly payment is approximately $2,093. In Year 1, she pays $25,116 total — but only $3,200 reduces her principal balance, while $21,916 goes to interest. That's 87 cents of every dollar going to interest in the first year.

By Year 10, her balance has dropped to around $286,000. By Year 15, roughly $241,000. Over the full 30 years, total interest paid: approximately $413,000 — more than the original loan amount. Total paid: $753,000 on a $340,000 loan.

The amortization schedule generated by this calculator shows Amy exactly how much she pays in principal and interest each year, and what her remaining balance is. Armed with this information, she can decide whether making extra payments makes financial sense, or whether a 15-year term would be worth the higher payment.

Why This Matters for Refinancing Decisions

The interest front-loading effect has a critical implication for refinancing: when you refinance, you restart the amortization clock on a new loan. If you're 10 years into a 30-year mortgage and you refinance to a new 30-year loan — even at a lower rate — you're resetting to the interest-heavy early years. You will pay more total interest on the refinanced loan than on the remaining 20 years of your original loan, even if the rate is lower.

This doesn't mean refinancing to a new 30-year term is always wrong — if the monthly savings are significant and the break-even is reasonable, it can still be the right choice. But it's important to compare total interest paid, not just monthly payments. The Refinance Savings Calculator helps you compare the full cost of staying vs. refinancing.

How to Read Your Amortization Schedule

The amortization table generated by this calculator shows one row per year of the loan. Here's exactly what each column means and how to use the information:

Year

The calendar year of the loan, starting at Year 1. Each row summarizes 12 months of payments for that year (except the last row, which may represent fewer months if the loan doesn't end on a year boundary).

Principal Paid

The total amount by which your loan balance decreased during that year through your regular payments. This is the sum of the principal portion of each of the 12 monthly payments during that year. In early years, this is a relatively small number. In later years, it grows substantially as interest accrual decreases.

Interest Paid

The total interest charged during that year — the sum of the interest portion of each monthly payment. This is the cost of borrowing during that period. In Year 1, this number is close to the annual rate multiplied by the starting balance. As your balance falls, annual interest decreases each year.

Remaining Balance

Your outstanding loan balance at the end of that year — what you would owe if you paid off the loan entirely on December 31 of that year. This number decreases each year as principal payments accumulate. Comparing this to your home's estimated value shows your equity at any given point.

Pro Tip: The "Remaining Balance" column is your friend when comparing refinance scenarios. If you're 7 years into a 30-year loan, find your balance from the Year 7 row and use it as the starting point for a new refinance calculation. This tells you exactly what you'd be borrowing if you refinance now, and how much total interest you'd pay on the remaining 23 years vs. a new loan.

How Refinancing Resets Your Amortization

When you refinance, your original loan is paid off and replaced by an entirely new loan with its own amortization schedule. The key effect: you start back at the beginning of the interest-heavy portion of the schedule.

Example: The Amortization Reset

Suppose you have a 30-year mortgage that you've been paying for 8 years. Your original loan was $350,000 at 7.25%. Your remaining balance is approximately $323,000, and you have 22 years left. If you keep your original loan, you'll make 22 more years of payments — and in those later years, an increasing share of each payment goes to principal.

If you refinance to a new 30-year loan at 6.25%, you're now on a new 30-year schedule — back to the early, interest-heavy years. Even though your rate dropped by 1%, you've added 8 years back to your payoff timeline and reset to the period where most of your payment is interest.

A 20-year refinance, by contrast, keeps you on a similar timeline to your original loan. A 15-year refinance could actually shorten your payoff date despite the refinance.

When the Reset Is Worth It

The amortization reset is worth accepting when:

  • The monthly payment reduction provides meaningful cash flow relief
  • The break-even period on closing costs is reasonable (typically under 3 years)
  • You plan to make extra principal payments to compensate for the reset
  • You're early enough in your original loan that the reset matters less
  • The rate drop is substantial enough that even the extended timeline results in lower total interest

Use the Break-Even Calculator and the Refinance Savings Calculator alongside this amortization table to make a fully informed comparison.

Common Scenarios

Scenario 1: Understanding Total Interest Cost on a New 30-Year Loan

James is considering a refinance from his current 7.50% loan to a new 30-year loan at 6.25%. He enters his $385,000 loan amount and generates the amortization schedule. He's startled to see that his total interest over 30 years will be approximately $447,000 — more than the loan itself. He then compares this to a 20-year option at 6.00%: total interest drops to approximately $257,000, with a monthly payment that's about $390 higher. He decides the 20-year option, while more demanding monthly, saves him nearly $200,000 in interest and is worth the sacrifice. The amortization table made this decision clear in a way that a simple rate comparison couldn't.

Scenario 2: Comparing 15-Year vs. 30-Year Options

Rebecca has a $310,000 loan. She's comparing a 30-year at 6.50% versus a 15-year at 5.875%. The 30-year schedule shows: monthly payment $1,961, total interest $396,000. The 15-year schedule shows: monthly payment $2,596, total interest $157,000. The difference in total interest: $239,000 saved by choosing 15 years. The monthly cost difference: $635/mo more for the 15-year. She uses the 15 vs 30-Year Calculator to run this comparison side by side and decides the interest savings justify the higher payment for her situation.

Scenario 3: Using Extra Payments to Change the Schedule

Thomas has a $425,000 loan at 6.75% for 30 years. His standard schedule shows total interest of approximately $568,000. He plans to add $300/month in extra principal payments starting immediately. Using the Extra Payment Calculator, he finds that $300/month extra reduces his payoff timeline by approximately 7 years and saves approximately $147,000 in interest. The amortization calculator helps him see the base schedule; the extra payment calculator shows him how additional payments reshape it.

Tips and Strategies

Run Schedules for Multiple Loan Options Side by Side

The most powerful use of this calculator is running multiple scenarios and comparing the outputs. Generate amortization schedules for 15-year, 20-year, and 30-year options at your expected rate. Compare the total interest row to see the lifetime cost difference, and compare the monthly payment to see the cash flow impact. This side-by-side view reveals trade-offs that a simple rate comparison obscures.

Use the Year-by-Year View for Long-Term Planning

The amortization table is a planning tool, not just a calculation result. Want to know your balance in 10 years when your children start college? Look at the Year 10 row's Remaining Balance. Planning to sell in 7 years? The Year 7 row shows exactly what you'll owe at that point. Thinking about making a lump-sum payment in Year 5 with an expected inheritance? The Year 5 balance tells you exactly how much you'd need to pay off the loan.

Combine With the Extra Payment Calculator

This amortization calculator shows your schedule with no extra payments. The Extra Payment Calculator shows you how adding extra principal payments each month shortens the schedule and reduces total interest. Using both together gives you complete flexibility to model "what if I pay the minimum?" vs. "what if I pay an extra $200 a month?"

Understand the Impact on Refinancing Late in Your Loan

If you're 20+ years into a 30-year mortgage, refinancing to a new 30-year loan is almost never advantageous from a total interest perspective. You're in the late stages where most of your payment is already going to principal. Starting over with a new 30-year loan would massively increase your total interest — even at a lower rate. A shorter-term refinance (10 or 15 years) might make sense if your current rate is very high, but run the amortization numbers first.

Check Your Balance Before a Major Decision

The Remaining Balance column in your amortization table answers a question many homeowners can't answer from memory: "What do I actually owe right now?" Knowing your precise balance helps you calculate your current LTV (combine with the Home Equity Calculator), determine how much cash-out is available, and plan extra payments strategically.

Frequently Asked Questions

Why does interest dominate early payments on a mortgage? +
Interest is calculated as a percentage of your outstanding balance. When you first take out the loan, the balance is at its maximum — so the interest portion of each payment is at its maximum too. As you make payments and reduce the balance, less interest accrues each month, and the fixed payment amount means more goes to principal. This front-loading effect is a mathematical consequence of the standard amortization formula, which is designed to produce equal payments throughout the loan term. It's not a trick by lenders — it's simply how compound interest works over time.
How does a shorter loan term affect amortization? +
A shorter loan term requires a higher monthly payment, but that higher payment contains a much larger principal component from the very first month. On a 15-year loan at the same interest rate as a 30-year loan, approximately 50–60% less total interest is paid over the life of the loan. The amortization balance drops faster, meaning you build equity more rapidly. The trade-off is a higher monthly obligation that reduces cash flow flexibility. A 15-year mortgage at 6% vs. a 30-year at 6.5% might save over $200,000 in interest on a $350,000 loan.
What happens to my amortization schedule if I make extra payments? +
Extra principal payments reduce your outstanding balance faster than the standard schedule. Because interest is calculated on the balance, a lower balance means less interest accrues each month — and since your payment stays the same, more of each subsequent payment goes to principal. The compounding effect of early extra payments is substantial: an extra $200/month on a 30-year loan early in the loan life can save 5–7 years of payments and tens of thousands in interest. The standard amortization schedule shown here assumes no extra payments; use the Extra Payment Calculator to model the accelerated schedule.
What is negative amortization? +
Negative amortization occurs when your monthly payment is less than the interest that accrues during that period. The unpaid interest is added to your loan balance, causing it to grow over time rather than decrease. Standard fixed-rate mortgages do not have negative amortization — the payment is always sufficient to cover interest and make some principal reduction. Negative amortization can occur with certain adjustable-rate mortgages (ARMs) that have payment caps, or with certain exotic loan products. If your balance is increasing month over month, you may be experiencing negative amortization — consult your loan servicer immediately.
How do I know my current principal-to-interest split right now? +
Your current monthly mortgage statement shows the exact split between principal and interest for that payment. You can also calculate it: take your current loan balance × (your annual rate ÷ 12) = this month's interest portion. Subtract that from your total payment to get the principal portion. For example: $280,000 balance × (6.5% ÷ 12) = $1,517 interest this month. If your payment is $1,896, then $379 goes to principal. Your loan servicer can also provide a full amortization schedule for your current loan on request.
Can I get a monthly (not yearly) breakdown? +
This calculator provides a year-by-year summary for readability — showing the cumulative principal paid, interest paid, and remaining balance at the end of each year. For a month-by-month breakdown of any specific year, divide the annual figures by 12 for an approximation. For the precise monthly breakdown, your loan servicer can provide a full amortization schedule at any point during the loan. They are typically required to provide this upon request. For 30-year loans, a full monthly schedule contains 360 rows — manageable in a spreadsheet but unwieldy on a webpage.
How does refinancing affect my amortization schedule? +
When you refinance, your existing amortization schedule ends and an entirely new one begins. The new schedule starts with your new loan balance, new interest rate, and new term. If you refinance to a longer term than you had remaining, you reset to the interest-heavy early years of a new schedule. If you refinance to a shorter term, you may accelerate the principal-paying phase. The critical insight: compare total interest remaining on your current loan to total interest on the new loan, not just the monthly payment. Generate amortization schedules for both scenarios and compare the "Total Interest" figures to see the true long-term cost of each option.
What is the amortization schedule for an ARM (adjustable-rate mortgage)? +
Adjustable-rate mortgages have amortization schedules that are fixed during the initial rate period (e.g., the first 5, 7, or 10 years for a 5/1, 7/1, or 10/1 ARM) and then change at each adjustment interval. During the fixed period, the schedule works exactly like a fixed-rate mortgage — it's fully predictable. After the first adjustment, the payment and schedule change based on the new rate, and they may change again at each subsequent adjustment. This calculator models fixed-rate loans only. For ARM scenarios, consult your lender or a mortgage calculator that specifically handles ARMs and displays the potential rate range scenarios.

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