📋 Amortization Schedule Calculator
Generate the complete month-by-month payment breakdown for any mortgage, auto, or personal loan. See exactly how much of each payment reduces your balance versus paying interest - and find out how much extra payments can save you. Enter your loan details and the full schedule builds instantly.
📋 Amortization Calculator
📋 Full Amortization Schedule
Run the calculator first to generate the schedule.
📐 How Amortization Works
What is Amortization?
Monthly Payment Formula
Each Month's Split
Power of Extra Payments
Interest-to-Principal Ratio Over Time
❓ Frequently Asked Questions
Amortization Schedule Calculator - Understanding Your Loan Payment by Payment
Most people who take out a mortgage know their monthly payment number, but very few know what's actually happening inside each payment. In the early years of a 30-year loan, the majority of every dollar you send the bank goes to interest - not to building equity. An amortization schedule makes that visible, payment by payment, so you understand what you're actually paying for and what levers you can pull to pay less.
How Amortization Actually Works
Amortization simply means paying off a debt through regular, scheduled payments over time. Each payment has two components: the interest charge for that period (calculated on the remaining balance) and the principal reduction (what's left of the payment after interest). Because interest is charged on the outstanding balance, the split shifts continuously - as you pay down the principal, less interest accrues, and more of each payment chips away at what you owe.
This front-loading of interest is not a scheme - it's just math. The bank lends you money for a long time and charges for the privilege. But it does mean that in practical terms, the fastest way to reduce your total interest cost is to reduce your principal balance as early as possible. Even a small extra payment in the first few years of a mortgage is worth far more than the same extra payment a decade later.
The Real Cost of a 30-Year vs 15-Year Mortgage
The difference in total interest between a 30-year and 15-year mortgage is often more than the original loan amount - and most borrowers never sit down and look at the actual numbers. Here's what a $400,000 loan looks like under different terms:
30-Year Mortgage at 6.75%
- Monthly payment: $2,595
- Total interest: ~$534,000
- Total cost: ~$934,000
- Year 1 interest share: ~93%
- Lower payment, more flexibility
- Equity builds very slowly early on
15-Year Mortgage at 6.25%
- Monthly payment: $3,431
- Total interest: ~$207,000
- Total cost: ~$607,000
- Year 1 interest share: ~72%
- Higher payment, less flexibility
- Equity builds much faster
The 15-year borrower pays $836 more per month but saves over $327,000 in total interest. Whether that trade-off makes sense depends entirely on your cash flow, other financial goals, and what you'd do with that $836 per month if you had it. Neither answer is universally right - the amortization schedule just makes the actual cost of each choice visible.
How Extra Payments Change Everything
The most powerful insight from an amortization schedule is how dramatically extra payments shift the math. Because interest is calculated on the remaining balance, every extra dollar you put toward principal today eliminates future interest charges on that dollar for every remaining month of the loan.
On a $400,000 loan at 6.75% for 30 years:
- Extra $100/month - saves ~$53,000 in interest, pays off about 4 years early
- Extra $200/month - saves ~$100,000 in interest, pays off about 7 years early
- Extra $500/month - saves ~$185,000 in interest, pays off over 11 years early
- One extra payment per year - saves ~$65,000 in interest, cuts about 5 years off
The earlier you start making extra payments, the more powerful each extra dollar becomes. An extra $200/month starting in Year 1 saves considerably more than the same $200/month starting in Year 10, because the principal reduction compounds forward through far more remaining months.
Bi-Weekly Payments - The Easy Extra Payment Strategy
One of the simplest ways to make extra payments without feeling a large hit is switching to bi-weekly payments. Instead of making 12 monthly payments, you make 26 half-payments per year. The math: 26 half-payments = 13 full monthly payments. That one extra full payment per year quietly applied to principal can shorten a 30-year mortgage by 4–5 years and save tens of thousands in interest - without dramatically changing your monthly cash flow.
The Monthly Payment Formula - Breaking It Down
The standard formula for a fixed-rate loan payment is:
M = P × [r(1+r)ⁿ] ÷ [(1+r)ⁿ − 1]
Where P is the principal amount, r is the monthly interest rate (annual rate divided by 12 and by 100), and n is the total number of monthly payments. For every period, interest is P × r and principal reduction is M − (P × r). The balance decreases by the principal portion each month, which is why the interest charge slowly falls and the principal portion slowly rises over time.
When Does It Make Sense to Refinance Instead of Making Extra Payments?
Refinancing is worth considering when current rates are at least 0.5–1% lower than your existing rate, you plan to stay in the home long enough to recover the closing costs (typically 2–3 years), and you're still early in your loan term. Refinancing resets your amortization clock - so if you're already 15 years into a 30-year loan, refinancing into another 30-year loan actually increases your total interest despite the lower rate. Use the amortization schedule to compare your remaining interest under the current loan versus a new refinanced loan before deciding.