Free Mortgage Amortization Calculator (2026)
Generate a full amortization schedule. Calculate instantly — no signup required. Updated for 2026.
What Is a Mortgage Amortization Calculator?
A mortgage amortization calculator generates a complete month-by-month payment schedule showing exactly how each payment is split between principal and interest over the entire life of your loan. The word “amortization” comes from the Latin amortire, meaning “to kill” — and that is precisely what an amortization schedule does: it shows you the timeline for killing off your debt.
What surprises most borrowers is how heavily front-loaded the interest is. In the early years of a 30-year mortgage, roughly 70-80% of each payment goes toward interest, with only 20-30% reducing your actual loan balance. This ratio gradually shifts over time until, in the final years, nearly all of your payment goes toward principal. Understanding this schedule is crucial for making informed decisions about extra payments, refinancing, and early payoff strategies.
How Does This Calculator Work?
You enter your loan amount, interest rate, and loan term. The calculator then generates a complete schedule — typically 360 rows for a 30-year loan or 180 rows for a 15-year loan — showing for each payment:
- Payment Number: Which month of the loan (1 through 360, for example).
- Payment Amount: Your fixed monthly principal + interest payment.
- Principal Portion: The amount that reduces your loan balance this month.
- Interest Portion: The amount that goes to your lender as the cost of borrowing.
- Remaining Balance: Your outstanding loan balance after this payment.
- Cumulative Interest Paid: Total interest paid from the first payment through this month.
The Amortization Formulas
Each month, the interest portion is calculated first:
Interest Payment = Remaining Balance × Monthly Interest Rate
The principal portion is the remainder:
Principal Payment = Total Monthly Payment − Interest Payment
The new balance is then:
New Balance = Previous Balance − Principal Payment
This process repeats each month, with the interest portion shrinking and the principal portion growing — a characteristic curve of amortization.
Step-by-Step Example
Consider a $320,000 loan at 6.25% for 30 years:
Monthly payment (P&I): $1,970.27
| Payment # | Payment | Principal | Interest | Balance |
|---|---|---|---|---|
| 1 | $1,970.27 | $303.60 | $1,666.67 | $319,696.40 |
| 2 | $1,970.27 | $305.18 | $1,665.09 | $319,391.22 |
| 12 | $1,970.27 | $322.13 | $1,648.14 | $316,283.11 |
| 60 | $1,970.27 | $411.98 | $1,558.29 | $297,596.44 |
| 180 | $1,970.27 | $728.45 | $1,241.82 | $236,985.49 |
| 300 | $1,970.27 | $1,288.13 | $682.14 | $128,813.44 |
| 360 | $1,970.27 | $1,960.06 | $10.21 | $0.00 |
Notice: In payment #1, only $303.60 goes to principal ($1,666.67 to interest). By payment #300, $1,288.13 goes to principal. Over 30 years, the total interest paid is approximately $389,297 — more than the original loan amount.
When Should You Use This Calculator?
- Planning extra payments: See how one extra payment per year or an extra $200/month can shave years off your mortgage and save tens of thousands in interest.
- Considering refinancing: Compare your remaining amortization schedule against a new loan to see if refinancing truly saves money after accounting for closing costs.
- Tax planning: Mortgage interest is tax-deductible (for itemizers), and the amortization schedule shows exactly how much interest you pay each year for tax purposes.
- Equity tracking: Monitor how quickly you are building equity — especially useful when planning to sell or take out a HELOC.
- Comparing loan terms: Visually understand why a 15-year mortgage saves so much more in interest than a 30-year, despite having higher monthly payments.
Tips for Getting Accurate Results
- Use your actual loan balance: If you are already making payments, enter your current remaining balance, not the original loan amount.
- Model extra payments: Even $100 extra per month on a $320,000 loan at 6.25% saves roughly $72,000 in interest and pays off the loan 5 years early.
- Check the crossover point: Find the month where your principal payment first exceeds your interest payment — on a 30-year loan, this typically happens around year 18-22.
- Consider biweekly payments: Paying half your mortgage every two weeks results in 26 half-payments (13 full payments) per year instead of 12 — effectively one extra payment annually.
- Factor in your tax bracket: The interest deduction makes the early years of a mortgage relatively more affordable for those who itemize deductions.
Key Takeaways
- On a 30-year mortgage, you often pay more in total interest than the original loan amount itself.
- The interest-to-principal ratio flips dramatically over the loan term — early payments are mostly interest, late payments are mostly principal.
- Making just one extra payment per year on a 30-year mortgage typically shortens the loan by 4-5 years.
- An amortization schedule is essential for understanding your equity position, tax deductions, and the true cost of your loan.
Frequently Asked Questions
Why does most of my early mortgage payment go to interest?
Interest is calculated as a percentage of your remaining loan balance. In the early years, your balance is at its highest, so the interest charge each month is large. As you gradually reduce the principal, less interest accrues, and more of your fixed monthly payment can go toward principal reduction. On a $320,000 loan at 6.25%, your first payment puts only $304 toward principal — but by year 25, over $1,200 per payment goes to principal.
How much interest will I pay over the life of a 30-year mortgage?
On a typical $320,000 mortgage at 6.25%, you will pay approximately $389,000 in total interest over 30 years — meaning the total cost of the home (principal + interest) exceeds $709,000. This is why even small rate reductions matter enormously. Reducing your rate by just 0.5% on this same loan saves approximately $38,000 in lifetime interest. Choosing a 15-year term instead would save roughly $227,000 in interest.
How do extra payments affect my amortization schedule?
Extra payments go directly toward principal reduction, which has a compounding effect: each dollar of extra principal eliminates future interest that would have been charged on that dollar for the remaining loan term. For example, $200 extra per month on a $320,000 loan at 6.25% pays off the mortgage in approximately 22 years instead of 30, saving over $120,000 in interest and giving you 8 years of payment-free living.
When does the principal-to-interest ratio flip in my mortgage?
On a standard 30-year fixed mortgage, the crossover point — where more of your monthly payment goes to principal than interest — typically occurs between month 216 and month 264 (years 18-22), depending on your interest rate. Higher rates push the crossover point later. At 6.25% on $320,000, the crossover happens around month 230 (approximately year 19). With a 15-year mortgage, the crossover occurs much sooner — typically around year 5-7.
Should I use my amortization schedule for tax deductions?
Yes, your amortization schedule shows the exact amount of mortgage interest you pay each year, which is valuable for tax planning. Mortgage interest on the first $750,000 of loan debt is tax-deductible if you itemize (for loans originating after December 15, 2017). In the early years, when interest payments are highest, the deduction is most valuable. Your lender also sends Form 1098 confirming the amount, but the amortization schedule lets you plan ahead.