Amortization Calculator

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Generate your complete loan amortization schedule — every payment broken down into principal and interest, with running balance.

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Monthly Payment

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Loan Amount$0
Total Interest$0
Total Cost$0
📊 Show Full Amortization Schedule
Month Payment Principal Interest Balance

📐 Formula

Monthly Payment = P × [r(1+r)^n] / [(1+r)^n − 1]. Monthly Interest = Remaining Balance × Monthly Rate. Monthly Principal = Payment − Interest

How to Use the Amortization Calculator

1

Enter loan details

Input the loan amount, annual interest rate, and term in months. A 30-year mortgage = 360 months; a 5-year car loan = 60 months.

2

Add an extra payment

Enter any additional monthly principal payment. Even $100/month extra on a 30-year mortgage saves thousands in interest and shortens the loan by years.

3

Review the schedule

Each row shows the payment number, total payment, interest portion, principal portion, and remaining balance — the most transparent view of any loan's true cost.

How Amortization Works: Why Early Payments Are Mostly Interest

Each loan payment covers the interest that has accrued since the last payment, with the remainder reducing the principal. Because the balance starts large, early payments are heavily weighted toward interest — on a 30-year mortgage, the first payment might be 85% interest and only 15% principal. As the balance shrinks, less interest accrues and more of each payment reduces principal. This creates the characteristic accelerating paydown curve: the final years of a 30-year mortgage see dramatic principal reduction per payment compared to the first years.

The Power of Extra Principal Payments

Extra principal payments in the early years of a loan have an outsized impact because they eliminate future interest charges that would otherwise compound over years. An extra $200/month on a $300,000, 30-year, 7% mortgage made from month 1 shortens the loan by approximately 7 years and saves over $100,000 in interest. The same $200/month added in year 20 saves considerably less. The mathematical benefit of extra payments is greatest at the start — making early principal reduction one of the highest guaranteed-return actions available.

Reading an Amortization Table for Refinancing Decisions

When refinancing, the amortization schedule reveals why refinancing in the later years of a loan often makes less sense. If you have 10 years remaining on a 30-year mortgage, you are now mostly paying principal — your interest burden is already low. Refinancing resets the amortization clock, front-loading interest again even if the new rate is lower. The breakeven analysis for any refinance should compare total interest paid on the existing schedule against total interest on the new schedule, not just the monthly payment difference.

Sources & Methodology

Calculations are based on the most current publicly available data from authoritative government and industry sources:

Frequently Asked Questions

An amortization schedule shows every payment of a loan broken down into principal (what you owe) and interest. Early payments are mostly interest; later payments are mostly principal. This is called negative amortization risk.
Making extra principal payments reduces your balance faster, which means less interest accrues. On a 30-year mortgage, paying an extra $200/month can cut 5–7 years off the loan and save tens of thousands in interest.
It varies by rate. At 7% APR on a $300,000 30-year mortgage, the first payment of ~$1,996 is about $1,750 interest and only $246 principal. By the final payment, it's almost entirely principal.
In early loan years, the majority of each payment goes toward interest — on a $400,000 30-year loan at 7%, the first payment is approximately $2,660: $2,333 interest and only $327 principal. By year 15, the split nears 50/50. By year 28, most of the payment is principal. Extra payments early save the most.
Making one extra principal payment per year on a $400,000 mortgage at 7% over 30 years saves approximately $70,000–$85,000 in total interest and cuts the loan term by 4–5 years. Apply the extra payment directly to principal and confirm with your lender that it reduces the balance, not just prepays future interest.