Mortgage Amortization Calculator
See your mortgage payment, total interest, and a year-by-year breakdown of principal, interest and remaining balance.
How to Use
- Enter the loan amount, the annual interest rate, and the loan term in whole years.
- The result shows your monthly payment, total interest, and total repayment, followed by a year-by-year breakdown of how much of that year's payments went to principal vs. interest and what balance remains at year-end.
Formula
- Monthly payment
- payment = loan_amount × monthly_rate ÷ (1 − (1 + monthly_rate)^−months)
- Each month
- interest = remaining_balance × monthly_rate; principal = payment − interest; remaining_balance −= principal
- Yearly rows
- each year sums that year's 12 months of principal paid and interest paid, and reports the balance remaining after the 12th
Worked Example
A $10,000 loan at 6% annual interest over a 3-year term.
- Monthly rate: 6 ÷ 100 ÷ 12 = 0.005
- Monthly payment: $10,000 × 0.005 ÷ (1 − 1.005⁻³⁶) ≈ $304.22
- Year 1: $3,135.94 of the year's payments goes to principal, $514.69 to interest, ending balance ≈ $6,864.06
- Year 2: $3,329.36 principal, $321.28 interest, ending balance ≈ $3,534.70
- Year 3: $3,534.70 principal, $115.93 interest, ending balance ≈ $0.00
Result: Monthly payment: $304.22 / Total interest: $951.90 / Total repayment: $10,951.90 / Year 1: $3,135.94 principal, $514.69 interest, $6,864.06 balance / Year 2: $3,329.36 principal, $321.28 interest, $3,534.70 balance / Year 3: $3,534.70 principal, $115.93 interest, $0.00 balance
About This Tool
What this tool does
This calculator finds your fixed monthly payment on a loan and then simulates it month by month to show, for each year of the loan, how much went to principal, how much went to interest, and what balance remains.
When to use it
Use it to see how the principal/interest split shifts over the life of a loan — early payments are interest-heavy, later ones are principal-heavy, even though the total payment stays the same — or to check the remaining balance at a specific point, such as before a planned sale or refinance.
What the result means
The yearly breakdown summarizes a full monthly schedule into one row per year (a monthly table for a 30-year loan would be 360 rows), which is how most real amortization tools present a long schedule while staying fully checkable against the underlying month-by-month math.
Assumptions & limitations
This assumes a fixed rate and a fixed monthly payment with no extra payments, skipped payments, or rate changes for the full term — see the Extra Mortgage Payment / Early Payoff Calculator for how additional payments change this schedule. This is an estimate, not a real lender's exact amortization schedule, which can include additional fees or rounding conventions specific to that lender.