Amortization Calculator
For a $250,000 loan at 6.5% over 30 years, the estimated monthly principal-and-interest payment is $1,580.17. This amortization calculator estimates how a fixed-rate loan balance changes over time from the loan amount, annual interest rate, and loan term in years. It returns the monthly payment, total payment, total interest, and a month-by-month schedule so you can see how each payment is split. An amortization schedule usually starts with a larger interest share because interest is charged on the remaining balance. As the balance drops, less of each payment goes to interest and more goes to principal. That makes this tool useful when you want to compare loan options, check the long-term cost of a mortgage or auto loan, or understand why a shorter term raises the payment but often cuts total interest sharply.
Quick answer
The calculator uses a standard fixed-rate amortization formula to estimate principal-and-interest payments.
What this tells you
- •The calculator uses a standard fixed-rate amortization formula to estimate principal-and-interest payments.
- •Each schedule row shows one month, the payment for that month, how much goes to principal, how much goes to interest, and the remaining balance after the payment posts.
- •Early payments usually show more interest than principal because the unpaid balance is highest at the start of the loan.
- •Longer terms often reduce the monthly payment but increase total interest because the balance stays outstanding for more months.
- •If the annual rate is 0%, the tool divides the loan amount evenly across all months instead of applying interest.
How to Use
- 1Enter the original loan amount you want to analyze. Use the financed balance, not the sticker price of the car or home.
- 2Enter the annual interest rate as a yearly percentage. For example, enter 6.5 for a 6.5% fixed rate.
- 3Enter the loan term in years. The tool converts that term into total monthly payments and builds the full schedule from there.
- 4Click Calculate to see the estimated monthly payment, total payment, total interest, payoff months, and the amortization table.
- 5Review both the payment and the schedule. A lower payment can still mean a much higher total borrowing cost if the term is much longer.
How It Works
Formula
For rates above 0%, Monthly Payment = P × r × (1 + r)^n ÷ ((1 + r)^n - 1). For a 0% loan, Monthly Payment = P ÷ n.P is the original loan amount, r is the monthly interest rate found by dividing the annual rate by 12 and converting it to decimal form, and n is the total number of monthly payments. After the tool finds the fixed payment, it builds the schedule one month at a time. Monthly interest equals the current balance multiplied by r. Principal paid equals the payment minus that interest charge. The remaining balance then falls by the principal paid, and the next month repeats the same process on the lower balance. The final row can include a small cents-level adjustment so the ending balance reaches zero cleanly.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
30-year fixed home loan example
This example shows why a long term can feel manageable each month but still cost a lot over time. In the first payment, most of the money goes to interest because the balance is still close to the full $250,000. By the end of the schedule, almost the full payment goes to principal because only a small balance is left. That shift is normal in a fixed-rate amortization schedule.
Five-year vehicle loan example
A shorter term pushes the monthly payment higher than a longer loan on the same balance, but it also pays down principal faster. Here, the first payment already sends more to principal than to interest. That is one reason many borrowers use an amortization calculator to compare an affordable payment against the full cost of borrowing before signing.
Zero-interest loan example
When the interest rate is 0%, the math becomes simple because every dollar of the payment reduces principal. The tool handles that case by dividing the balance by the total number of months. This makes the example useful for employer loans, family loans, or promotional financing where no interest is charged during the full term.
15-year mortgage payoff example
This payment is much higher than a 30-year alternative would be, but the interest cost is far lower because the balance disappears in half the time. Even the first payment sends more than $1,100 to principal, which is a much stronger start than many long mortgages. Borrowers often compare schedules like this when deciding between lower monthly pressure and faster equity growth.
Small higher-rate loan example
Smaller loans can still become expensive if the rate is high enough. This example keeps the term short, which limits the total interest to a little over $1,266. It is a good reminder that both the rate and the term shape the final cost, not just the loan amount.
How loan term changes cost on the same $250,000 balance
These comparison rows use the same $250,000 principal and 6.5% annual rate so you can see how changing only the term affects payment and total interest.
| Loan term | Estimated monthly payment | Total interest | Total payment |
|---|---|---|---|
| 10 years | $2,838.70 | $90,643.93 | $340,643.93 |
| 15 years | $2,177.77 | $141,998.31 | $391,998.31 |
| 20 years | $1,863.93 | $197,343.88 | $447,343.88 |
| 30 years | $1,580.17 | $318,861.22 | $568,861.22 |
The 30-year option lowers the payment by about $1,258.53 compared with the 10-year option, but it adds more than $228,000 in extra interest. An amortization schedule helps make that tradeoff visible before you commit to the loan.
How to read an amortization schedule
Reading only the monthly payment can hide the full cost of borrowing. The schedule shows the tradeoff between cash flow and interest cost because stretching a loan over more months lowers the payment but usually keeps the balance alive longer and increases total interest.
Most lender statements include more than principal and interest. Escrow for taxes and insurance, prepaid interest, servicing fees, or other charges can sit on top of the base payment shown here. Use this tool to understand the principal-and-interest pattern, then compare that estimate with the official loan estimate, closing disclosure, or billing statement.
If you plan to make extra payments, this schedule works best as a baseline. Extra principal usually shortens payoff time and cuts interest, but the exact effect depends on when the payment posts and how your lender applies it. A standard amortization calculator is still helpful because it shows what the loan costs before any acceleration strategy is added.
Common mistakes
- Entering a monthly rate instead of an annual rate, such as typing 0.5 when the loan is actually 6% per year.
- Comparing two loans by monthly payment alone and ignoring the total interest and total payment figures.
- Assuming the table includes escrow, taxes, insurance, or lender fees when it only estimates principal and interest.
- Using an advertised rate or term that does not match the final lender disclosure or note.
- Applying a fixed-rate amortization estimate to an adjustable-rate loan, interest-only loan, or a plan with extra principal payments.
Limitations
This model assumes a fixed interest rate, regular monthly payments, and no extra payments, skipped payments, refinance events, or rate resets. It rounds displayed schedule rows to cents and adjusts the last row so the balance ends at zero. It does not model daily interest conventions, odd first payment periods, escrow collections, taxes, insurance, closing costs, late fees, or lender-specific posting rules. Use it to understand the shape and cost of a standard amortizing loan, not to replace an official payoff quote or disclosure package.
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