Amortization Calculator

Introduction

This Amortization Calculator generates a month-by-month payment schedule for a fixed-rate loan. You enter the starting balance, interest rate, and term to see how each payment splits between principal and interest and how the remaining balance falls over time. Use the table to plan extra payments or to compare a fifteen-year payoff against thirty years.

Who this calculator is for

Borrowers who want to see the mechanics behind their mortgage payment use an amortization schedule more often than they expect. You might be five years into a loan and curious how much equity you have built, or you might be shopping and want proof that early payments are mostly interest. Financial planners also use schedules to illustrate why small extra principal payments can shorten a loan dramatically.

If you only need a single monthly PITI figure with taxes and insurance, the Mortgage Calculator is faster. Return here when the question is how the loan balance changes over time, not what you owe the county each year.

What it estimates

Given a level-payment fixed-rate loan, the engine computes the constant monthly payment that retires the balance in the chosen term. Each row applies one month of interest to the opening balance, assigns the remainder to principal, and reports the closing balance. Totals at the bottom sum interest paid and principal retired across the full schedule.

The schedule assumes on-time payments with no prepayment, no escrow, and no rate changes. Biweekly payment programs, skipped payments, and recasts after a large lump sum are not built in; for extra monthly payments, use the Mortgage Payoff Calculator.

Inputs explained

Three core inputs drive the entire table. Keep units consistent with your loan documents.

• Loan amount: Starting principal balance. For a new purchase, this is price minus down payment. For an existing loan, use the current payoff quote from your servicer.
• Interest rate: Annual fixed note rate. The calculator converts it to a monthly rate internally.
• Loan term: Number of years until the loan is paid off at the standard payment. Common entries are thirty and fifteen.
• Start date (optional): Some versions label rows with calendar months for reference; payment math does not depend on the date.

How to read the results

The payment column stays flat on a fixed-rate loan while the interest column shrinks and the principal column grows. Early in the schedule, interest can exceed seventy percent of the payment; halfway through the term, principal often pulls even. The remaining balance column shows how much you would still owe if you sold or refinanced on that date.

Scan cumulative interest to compare terms: the same loan amount at a shorter term has higher payments but much less total interest. Export or screenshot the year-five row when you are modeling a refinance break-even in the Refinance Calculator.

Worked example

A $300,000 loan at 6.00% for thirty years produces a monthly payment of about $1,799. Month one applies roughly $1,500 to interest and $299 to principal. After twelve months the balance is near $296,400; after five years, about $279,200. Total interest over the full thirty years is approximately $347,500 if every payment is on time.

The same $300,000 at 6.00% for fifteen years raises the payment to about $2,532 but cuts total interest to near $155,700. Running both schedules side by side makes the tradeoff visible without guessing.

Practical use cases

Pick a target free-and-clear date and read which row hits zero balance. Mark the row where balance drops below eighty percent of original value to think about PMI removal on conventional loans. Sellers estimating net proceeds can subtract the balance on their expected closing date from the sale price.

Investors comparing owner-occupied financing to a cash-out strategy can print year-one interest for a tax discussion with an accountant. Teachers and counselors use the table to show why doubling up one extra principal payment early beats the same dollar spread across later years.

Limitations and related tools

Adjustable-rate loans, interest-only periods, negative amortization, and balloon notes are not supported. Escrow for taxes and insurance never appears in the schedule because it is not part of loan amortization. Servicer rounding, payment due dates on the first versus the fifteenth, and per-diem interest at payoff can differ by a few dollars from this math.

For PITI with tax and insurance, use the Mortgage Calculator. For accelerated payoff with a fixed extra each month, use the Mortgage Payoff Calculator. Program-specific fees for FHA and VA loans belong in those dedicated calculators, not in a plain amortization table.

How It Works

1. Enter loan balance. Type the starting principal: new loan amount or current payoff from your servicer.
2. Set rate and term. Enter the fixed annual interest rate and the loan term in years.
3. Generate the schedule. Click Calculate to build the month-by-month table with payment, interest, principal, and balance.
4. Find your milestone row. Scroll to the month you care about: five-year mark, PMI removal, or final payment. Note balance and cumulative interest.

Formula and methodology

The Amortization Calculator uses this identity for the scenario you enter. A bank, payroll system, or tax program may round on a 360-day year or average daily balance, so a statement can differ by a small amount.