Amortization Calculator
See exactly how every payment breaks down — and how much extra payments can save you. Results update instantly.
Loan Details
Current avg 30-yr fixed: 6.4% (Freddie Mac, Apr 2026)
Added to every payment → reduces interest and payoff time
Results
Monthly Payment
$1,876.52
Principal & Interest only
Total Interest
$375,546.38
Total Payments
$675,546.38
💰 Extra Payment Impact
Interest Saved
—
Time Saved
—
Remaining Balance Over Time
Watch your balance decline — slowly at first, then accelerating as more of each payment goes to principal.
Amortization Schedule
| Year | Payment | Principal | Interest | Balance |
|---|
How to Use This Amortization Calculator
Enter your loan amount — the amount you're borrowing, not the purchase price. For a mortgage, that's the home price minus your down payment. Set your annual interest rate and loan term. The Start Date determines when your first payment is due and when the loan pays off.
The most powerful field in this calculator is the Extra Monthly Payment. Even $100–$200 extra per month produces dramatic results — often shaving years off the loan and saving tens of thousands in interest. Enter different amounts to find your sweet spot between payment comfort and interest savings.
Hit Calculate and you'll see your full monthly payment, total interest, payoff date, and the complete year-by-year amortization schedule. Toggle between Yearly and Monthly views depending on how much detail you want.
How Amortization Works
Every fixed-rate loan uses the standard amortization formula: M = P × [r(1+r)^n] ÷ [(1+r)^n − 1], where P is principal, r is the monthly rate, and n is the number of payments. This gives you one fixed monthly payment for the entire loan term.
The payment stays the same every month, but the split between interest and principal changes dramatically. In the first month of a $300,000 loan at 6.4%, you pay $1,600 in interest and only $276 in principal. By year 25, those numbers flip: $276 interest and $1,600 principal. This is why selling or refinancing early costs so much — you've been paying mostly interest.
The Math Behind Extra Payments
Every extra dollar applied to principal reduces your balance immediately. That lower balance means less interest accrues next month — and every month thereafter. This compounding effect makes early extra payments extraordinarily powerful.
On a $300,000 loan at 6.4% for 30 years: adding $200/month extra saves approximately $72,000 in interest and pays off the loan 6 years early. Adding $500/month saves $130,000 and finishes 11 years early. The math is nonlinear — doubling your extra payment more than doubles the savings because each extra payment builds on the previous one.
Example: $300,000 at 6.4%, 30 years
| Extra/mo | Total Interest | Interest Saved | Payoff |
|---|---|---|---|
| $0 | $375,386 | — | Apr 2056 |
| $100 | $319,421 | $55,965 | Jun 2052 |
| $200 | $275,943 | $99,443 | Mar 2050 |
| $500 | $203,041 | $172,345 | Sep 2045 |
Understanding Your Results
Monthly Payment
This is your P&I payment — principal and interest only. Your actual payment to the lender will be higher if your lender collects escrow for property taxes and homeowner's insurance. Those costs don't affect your amortization schedule.
Total Interest
On a 30-year $300,000 mortgage at 6.4%, you'll pay $375,386 in interest — more than the original loan amount. This is the number that motivates most extra payment strategies. Even small additional payments chip away at this figure significantly.
Reading the Schedule
The yearly view shows annual totals: how much you paid, how much went to principal, how much to interest, and your balance at year-end. The monthly view shows every individual payment. Use this to find specific milestones: when your balance drops below $250k, when you hit 20% equity (PMI cancellation trigger), or when your remaining balance equals your annual income.
Frequently Asked Questions
How much interest do I save by making extra mortgage payments?
On a $300,000 loan at 6.4% for 30 years, adding just $200/month saves approximately $99,000 in interest and cuts 6 years off your loan. The impact is front-loaded: extra payments in the first decade save roughly 3x more than the same payments in the final decade because interest is charged on a higher balance early on.
What is an amortization schedule?
An amortization schedule shows every payment's breakdown: how much goes to interest, how much reduces principal, and the remaining balance. On a 30-year mortgage, the first payment is roughly 85% interest and 15% principal. By year 20, that split has reversed. The schedule shows exactly when you cross milestones like 50% equity or payoff.
Should I make biweekly payments instead of monthly?
Biweekly payments equal 26 half-payments per year — the equivalent of 13 monthly payments instead of 12. On $300,000 at 6.4%, biweekly saves about $52,000 in interest and pays off 4–5 years early. The benefit is automatic: one extra payment per year without extra discipline. Check your lender — some charge fees for biweekly processing.
What is mortgage recasting?
Recasting means making a large lump-sum principal payment, then having your lender recalculate your monthly payment based on the new lower balance. Unlike refinancing, recasting keeps your original rate and term and costs $150–$500 versus thousands for a refinance. It's ideal if you receive a windfall and want lower monthly payments without the hassle and cost of refinancing.
Is it better to refinance or make extra payments?
Refinancing wins when you can drop your rate by 0.75%+ and plan to stay 3+ years. Extra payments win when your current rate is already competitive, you're mid-loan (less interest to save), or you want payment flexibility. With rates potentially dropping from 6.4% to 5.5%+, refinancing in 1–2 years may outperform extra payments — use this calculator to model both scenarios.
Do extra payments go directly to principal?
Only if you specifically designate them. When sending extra money, always include a note or use your lender's online system to apply it to "principal only." Without clear instructions, lenders may apply it toward future payments instead — which doesn't reduce your balance the same way. Verify with your lender how to designate extra principal payments correctly.
What is a balloon payment loan?
A balloon loan has a large lump-sum payment due at the end — typically after 5–7 years of standard payments calculated on a 30-year schedule. Monthly payments are lower, but the final payment can be 80–90% of the original loan amount. These were common before 2008. Today, most US mortgages are fully amortizing — no balloon payment required.