Free Amortization Calculator Online
Use this free amortization calculator to see exactly how your loan balance decreases over time — with a year-by-year breakdown of principal paid, interest charged, and remaining balance. Calculate online in seconds with no sign-up required.
Monthly Payment
Principal + interest only
How Loan Amortization Works
When you take out a fixed-rate loan, your lender calculates a payment amount that stays the same every month for the life of the loan. What changes each month is the split between principal and interest. This is what our free online amortization calculator makes visible.
In the first year of a 30-year, $300,000 mortgage at 6.5%, roughly $19,400 of your payments go to interest — and only about $3,400 reduces your actual balance. By year 25, those numbers flip. The math is straightforward: interest is always calculated on the current outstanding balance. As the balance drops, less interest accrues each month, and more of your fixed payment chips away at principal.
The Formula
M = P × [r(1+r)ⁿ] / [(1+r)ⁿ−1]
P = loan amount, r = monthly rate (annual ÷ 12 ÷ 100), n = total months
Why the Amortization Schedule Matters
Extra Payments Have Outsized Impact
Any extra money you put toward principal in early years eliminates multiple future interest charges. On a $300k loan at 6.5%, one extra $1,896 payment in year 1 saves you about $3,500 in interest over the life of the loan.
Tax Deduction Planning
Mortgage interest is often tax-deductible. The amortization calculator tells you exactly how much interest you paid in any given year — useful for itemizing deductions on your federal return.
Refinance Break-Even Analysis
Knowing your remaining balance and current interest split helps you decide whether refinancing makes financial sense. If you are past the midpoint of your loan, most of your payment is already principal — refinancing typically restarts the cycle.
Free Amortization Calculator — Quick Reference Examples
| Loan Amount | Rate | Term | Monthly Payment | Total Interest | Total Cost |
|---|---|---|---|---|---|
| $200,000 | 5.0% | 15 years | $1,582 | $84,686 | $284,686 |
| $300,000 | 6.5% | 30 years | $1,896 | $382,643 | $682,643 |
| $400,000 | 7.0% | 30 years | $2,661 | $557,955 | $957,955 |
| $150,000 | 4.5% | 20 years | $949 | $77,828 | $227,828 |
Calculated using the standard amortization formula. Try these scenarios in the free online calculator above. Actual rates and fees vary by lender.
Front-Loading vs. Back-Loading Interest
The hardest thing for first-time borrowers to internalize is how front-loaded the interest is. On a 30-year amortization schedule, you will pay about 50% of your total lifetime interest in just the first 10 years. On a $300,000 loan at 6.5%, that is roughly $175,000 in interest paid before you hit the halfway point of the loan term.
This is why financial advisors often recommend attacking the principal aggressively early on. Even rounding up your monthly payment by $50 or $100 can shave a year or more off a 30-year loan. Use this free amortization calculator to model your specific numbers online — run the base case, then try adding $200/month and see the difference. Most people are surprised how much that small change compresses the schedule.
Shorter terms like 15-year loans have a steeper amortization — the balance drops faster because you are paying more principal each month. The interest rate is also usually 0.5–0.75% lower than a 30-year, amplifying the savings further. The trade-off is a higher monthly payment that reduces cash-flow flexibility.
4 Ways to Pay Down Your Loan Faster
Make Biweekly Payments
Pay half your monthly amount every two weeks instead of once a month. Because there are 26 biweekly periods per year, you end up making 13 full payments instead of 12 — knocking years off your amortization schedule automatically.
Apply Windfalls to Principal
Tax refunds, bonuses, and inheritance payments hit principal directly when you designate them as such. A $5,000 lump sum on a $300k loan at 6.5% in year 3 saves about $9,500 in future interest over the remaining life of the loan.
Refinance to a Shorter Term
If rates have dropped since you originated your loan, refinancing to a 15-year term can dramatically accelerate your amortization schedule and lower your total interest paid — even though your monthly payment goes up.
Round Up Every Payment
If your payment is $1,847, pay $1,900 or $2,000. The extra $53–$153 goes entirely to principal. Small consistent additions compound over a 30-year amortization schedule into thousands of dollars in savings.
Frequently Asked Questions
Disclaimer: This free online amortization calculator is provided for educational and informational purposes only. Results are based on a standard fixed-rate amortization formula and do not account for fees, PMI, taxes, insurance, or variable rate adjustments. Actual loan terms vary by lender. Consult a licensed financial or mortgage professional before making borrowing decisions.
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