Amortization Calculator - Free Online Tool

Calculate your loan payments, total interest, and full amortization schedule with extra payment scenarios

An amortization calculator is one of the most powerful tools you can use when taking out a loan. Whether you are buying a home, financing a car, or consolidating debt, understanding how your loan amortizes over time puts you firmly in control of your financial future. This free amortization calculator shows you exactly how every single payment breaks down between principal and interest, gives you a complete amortization schedule, and allows you to model different extra payment scenarios to see how much interest you can save. Amortization is the process of paying off a debt over time through regular scheduled payments. With a standard amortizing loan, each payment covers the interest that has accrued since the last payment, with the remainder reducing your outstanding principal balance. In the early years of a loan, a larger portion of each payment goes toward interest. As the balance decreases, more of each payment goes toward principal. This front-loading of interest is what makes extra payments so powerful — every dollar of principal you pay down early eliminates the compounding interest that would have accrued on that balance for the remaining life of the loan. For a $200,000 mortgage at 6.5% over 30 years, your monthly payment is $1,264.14. Over the full 30-year term, you will pay $255,089.44 in interest on top of the $200,000 principal — meaning you pay 127% of the original loan amount just in interest charges alone. Add an extra $200 per month to that payment, however, and you save over $68,000 in interest and pay off the loan 6 years early. This calculator lets you visualize exactly those kinds of trade-offs instantly. The calculator supports three types of extra payments simultaneously: a recurring extra monthly payment (the most impactful option), an annual lump-sum payment (great for year-end bonuses), and a one-time lump-sum payment at any point in the loan term. You can combine all three to model your optimal payoff strategy. The before-and-after comparison instantly shows you the interest saved and months eliminated from your loan term. For homebuyers and mortgage borrowers, the Mortgage mode adds PITI (Principal, Interest, Taxes, Insurance) fields including property tax, home insurance, PMI (private mortgage insurance), and HOA fees. The calculator automatically computes your full monthly housing payment and tracks when your PMI will drop off once your loan-to-value ratio reaches 80%. This gives you the true total monthly cost of homeownership rather than just the principal and interest component. The bi-weekly payment comparison is another powerful feature. By paying half your monthly payment every two weeks instead of one full payment once a month, you effectively make 26 half-payments (13 full payments) per year instead of 12. That extra payment per year can shave years off your loan and save tens of thousands of dollars in interest on a 30-year mortgage — all without feeling like a significant budget change. Every calculation comes with a complete amortization schedule showing all payments month by month, plus a year-by-year annual summary. You can switch between views, export the full schedule to CSV for use in Excel or Google Sheets, or print a clean copy for your records. The visual charts — including a principal vs. interest donut chart and a year-by-year stacked bar chart — make it easy to see the big picture at a glance. This calculator handles any type of amortizing loan: mortgages, auto loans, personal loans, student loans, and business loans. Whether you are just starting to research loan options, comparing competing lender offers, or strategizing on how to pay off an existing loan faster, this tool gives you the clarity and detail you need to make informed financial decisions.

Understanding Loan Amortization

What Is Loan Amortization?

Loan amortization is the systematic process of paying off a debt through fixed, scheduled payments over a defined period. Each payment is split into two components: an interest portion that compensates the lender for the outstanding balance, and a principal portion that reduces what you owe. The defining characteristic of an amortizing loan is that the total payment stays constant throughout the term even as the split between interest and principal shifts dramatically. In month one, perhaps 85% of your payment might be interest and only 15% principal. By the final payment, nearly 100% is principal. This happens because interest is calculated as a percentage of the remaining balance — as the balance falls, so does the interest owed, leaving more of each fixed payment to reduce the principal.

How Is the Monthly Payment Calculated?

The standard amortization payment formula is: M = P × [r(1+r)^n] / [(1+r)^n - 1], where M is the monthly payment, P is the principal loan amount, r is the monthly interest rate (annual rate divided by 12 and converted from percentage to decimal), and n is the total number of monthly payments (years × 12). This formula yields the fixed payment that will exactly zero out the balance after n payments. Each subsequent period, the interest charge equals the current balance multiplied by the monthly rate, and the principal payment equals the total payment minus that interest charge. With extra payments, the principal reduces faster, so subsequent interest charges are lower, and the loan terminates earlier than the original n payments.

Why Does Amortization Planning Matter?

Understanding your amortization schedule is critical for several financial decisions. First, it reveals the true cost of borrowing — a $300,000 mortgage at 7% over 30 years costs over $418,000 in total payments, meaning you pay 40% above the loan amount in interest alone. Second, it quantifies the value of making extra payments: even an additional $100/month early in a loan can save tens of thousands of dollars over the loan's life because it compounds forward in interest savings. Third, for tax planning purposes, the exact interest paid each year (visible in the annual schedule) helps calculate mortgage interest deductions. Fourth, comparing loan offers side-by-side with this calculator reveals which option truly costs less over time, regardless of which has a lower monthly payment.

Limitations and Assumptions

This calculator models standard fixed-rate fully amortizing loans. It does not handle variable-rate (ARM) mortgages where the rate adjusts periodically, interest-only loans where principal is not paid during an initial period, or balloon loans where a large lump sum is due at the end of a shorter payment term. The actual interest and payment amounts from your lender may differ slightly due to per-diem interest adjustments for your specific closing or first payment date, different day-count conventions, escrow adjustments, or lender-specific rounding rules. For mortgage purposes, this calculator does not account for mortgage insurance premium schedules specific to FHA or VA loans, origination fees, or points paid at closing. Always confirm calculations with your lender's official loan documents.

Amortization Formulas

Monthly Payment (M)

M = P × r(1 + r)^n / ((1 + r)^n − 1)

Calculates the fixed monthly payment for a fully amortizing loan, where P is the principal, r is the monthly interest rate (annual rate ÷ 12 ÷ 100), and n is the total number of payments (years × 12).

Interest Portion

Interest = Balance × r

The interest charged in any given month equals the outstanding loan balance multiplied by the monthly interest rate. Early in the loan, this is the majority of each payment.

Principal Portion

Principal = M − Interest

The principal paid each month is the fixed payment minus the interest portion. As the balance decreases over time, more of each payment goes toward reducing the principal.

Remaining Balance After Payment k

B(k) = P × [(1 + r)^n − (1 + r)^k] / [(1 + r)^n − 1]

Calculates the remaining loan balance after k payments have been made, useful for determining equity at any point in the loan term.

Reference Tables

Amortization Breakdown: $200,000 at 6% Over 30 Years

Shows how the interest-to-principal ratio shifts over the life of a standard 30-year mortgage. Monthly payment is $1,199.10. Total interest paid: $231,677.

Year	Annual Interest	Annual Principal	Interest %	Remaining Balance
1	$11,933	$2,456	83%	$197,544
5	$11,349	$3,040	79%	$186,109
10	$10,377	$4,012	72%	$167,371
15	$8,954	$5,435	62%	$142,098
20	$6,853	$7,536	48%	$107,795
25	$3,731	$10,658	26%	$60,609
30	$71	$14,318	0.5%	$0

Worked Examples

Build an Amortization Schedule for a $250,000 Mortgage

Loan amount: $250,000, interest rate: 6.5% annual, term: 30 years (360 payments).

Convert annual rate to monthly: r = 6.5% ÷ 12 = 0.5417% = 0.005417

Calculate total payments: n = 30 × 12 = 360

Apply the formula: M = 250,000 × 0.005417 × (1.005417)^360 / ((1.005417)^360 − 1) = $1,580.17

Month 1 interest: $250,000 × 0.005417 = $1,354.17

Month 1 principal: $1,580.17 − $1,354.17 = $226.00

Month 1 ending balance: $250,000 − $226.00 = $249,774.00

Total payments over 30 years: $1,580.17 × 360 = $568,861

Total interest: $568,861 − $250,000 = $318,861

Monthly payment of $1,580.17 with $318,861 in total interest over 30 years — 127.5% of the original loan amount paid in interest alone.

Impact of $100/Month Extra Payment on a $250,000 Mortgage

Same $250,000 loan at 6.5% for 30 years, but adding $100 extra to principal each month.

Standard payment: $1,580.17/month for 360 payments, total interest: $318,861

With $100 extra: effective payment = $1,680.17/month

Month 1: interest = $1,354.17, principal = $226.00 + $100 = $326.00

Balance drops faster, so each subsequent month's interest is lower

Loan pays off in approximately 304 months (25 years 4 months) instead of 360

Total interest with extra payments: approximately $248,840

Interest saved: $318,861 − $248,840 = $70,021

An extra $100/month saves approximately $70,021 in interest and pays off the loan 56 months (nearly 5 years) early — for a total extra outlay of only $30,400.

How to Use the Amortization Calculator

Enter Your Loan Details

Type your loan amount (the amount you are borrowing), the annual interest rate (APR from your lender), and the loan term in years. You can add extra months for fine-tuning. The calculator auto-updates results as you type.

Add Extra Payments (Optional)

Click 'Extra Payments' to expand the extra payment section. Enter an extra monthly amount, an annual lump sum, or a one-time payment at a specific payment number. Watch the interest savings and months saved update instantly in the results panel.

Explore the Charts and Comparisons

Use the Principal vs Interest donut chart to see what proportion of your total cost is interest. Switch to the Annual Breakdown tab for a year-by-year stacked bar view. Scroll down to the Bi-Weekly Comparison table to see how switching payment frequency could save you thousands.

View, Export, or Print the Schedule

Click 'Show Schedule' to expand the full amortization table. Toggle between monthly and annual views. Use 'Export CSV' to download the schedule as a spreadsheet, or 'Print' to get a printer-friendly version of your complete payment schedule.

Frequently Asked Questions

What is an amortization schedule and why do I need one?

An amortization schedule is a complete table showing every loan payment broken down into its interest and principal components, along with the remaining balance after each payment. You need it to understand exactly where your money is going each month, how much equity you are building, and how much interest you are paying over the life of the loan. It is essential for tax planning (mortgage interest deductions), for deciding whether refinancing makes sense, and for modeling the impact of making extra payments. Without the schedule, you only see the monthly payment amount — with it, you see the full financial picture of your loan.

How much can I save by making extra payments?

The savings depend on your loan amount, rate, remaining term, and the size of the extra payment. As a rule of thumb, on a $200,000 mortgage at 6.5% over 30 years, an extra $100/month saves roughly $26,000 in interest and cuts about 4 years off the loan. An extra $500/month saves over $85,000 and pays off the loan in about 19 years instead of 30. Extra payments are most effective early in the loan when the balance is highest, because every dollar of principal eliminated removes its compounding interest for all remaining years. Use this calculator to model your specific scenario and see the exact savings.

What is the difference between monthly and bi-weekly mortgage payments?

Monthly payments mean 12 payments per year. Bi-weekly payments mean a half-payment every two weeks, which equals 26 half-payments — the equivalent of 13 full monthly payments per year. That one extra full payment per year is applied entirely to principal, reducing the balance faster and saving significant interest. On a 30-year mortgage, switching to bi-weekly payments typically saves 4–6 years of payments and tens of thousands of dollars in interest. The key is that bi-weekly is not the same as twice-monthly: twice-monthly is 24 payments per year (same as monthly), while true bi-weekly is 26 payments per year.

What is PMI and when does it go away?

Private Mortgage Insurance (PMI) is insurance that protects the lender if you default on your loan. It is typically required when your down payment is less than 20% of the home's purchase price, meaning your loan-to-value (LTV) ratio exceeds 80%. PMI typically costs 0.3% to 1.5% of the original loan amount per year, added to your monthly payment. Under the Homeowners Protection Act, you have the right to request PMI cancellation once your LTV reaches 80%, and lenders must automatically terminate it when it reaches 78%. Making extra principal payments accelerates this process. This calculator shows exactly which payment number your LTV hits 80% so you know when to request cancellation.

What does PITI mean in a mortgage payment?

PITI stands for Principal, Interest, Taxes, and Insurance — the four components that make up a complete monthly mortgage payment. Principal is the portion reducing your loan balance. Interest is the lender's cost for extending credit. Taxes are your property taxes, which lenders often collect monthly into an escrow account and pay on your behalf annually. Insurance includes homeowner's insurance (and sometimes flood insurance) also held in escrow. For most mortgage qualification purposes, lenders look at your full PITI payment as a percentage of your gross income, not just the principal and interest. This calculator's Mortgage mode computes all four components plus optional HOA fees.

Why does the interest rate matter so much over a long loan term?

Interest rate has a compounding impact on total loan cost over long terms. On a $300,000 30-year mortgage, the difference between 6% and 7% is only about $186/month in payment, but the total interest paid jumps from $347,515 to $418,527 — a difference of over $71,000. Even a 0.5% rate difference adds up to roughly $33,000 over 30 years. This is why shopping for the best rate and considering points to buy down the rate can be financially significant decisions. It is also why refinancing when rates drop meaningfully can save substantial money, even after accounting for closing costs, especially if you have many years remaining on your loan.