Amortization Calculator - Loan Schedule Breakdown

An amortization calculator shows how a fixed-rate installment loan can be paid down from the opening balance to zero. Enter the amount borrowed, annual interest rate, repayment term, and recurring extra payment to estimate the regular monthly payment, modeled interest, total paid, and number of payments. The schedule turns a single quote into a month-by-month view of what happens to the debt.

Use it for a mortgage, auto loan, personal loan, student loan, or home-improvement loan with regular monthly payments. It shows how much of the first payment reduces principal, how much interest a term may cost, and how recurring extra principal can shorten the modeled schedule.

• • Estimate a payment: Enter the amount financed and note rate to see the scheduled principal-and-interest payment under the formula shown below.
• • Compare borrowing costs: Keep the loan amount fixed while testing two rates or terms. A lower monthly payment is not necessarily the lower-cost choice.
• • Study principal progress: Use the balance column to see how much debt remains after a month or a year, rather than relying on the payment alone.
• • Test regular extra payments: Enter an additional monthly amount to estimate months removed and interest saved when the extra money is applied directly to principal.

Early payments usually contain a larger interest portion because interest is charged against the largest balance. Later payments generally devote more of the same scheduled amount to principal. This pattern is why a long loan can have a manageable payment but a substantial lifetime interest total.

This page models principal and interest for a fixed annual rate with monthly periods. It does not calculate a contractual payoff quote, escrow, taxes, insurance, lender fees, late charges, variable-rate changes, or daily-interest adjustments. Use the lender's disclosure for the amount legally due.

For a payment and total-cost view without the detailed rows, see the Loan Calculator. Return here when you want to inspect how each payment changes the balance.

The calculator converts the annual rate to a monthly decimal rate and converts years to a total number of monthly periods. It then builds one row at a time. Interest for a row is based on the opening balance. The payment covers that interest first, and the remaining amount reduces principal.

• M: Regular monthly principal-and-interest payment.
• P: Original principal borrowed, in dollars.
• r: Monthly decimal rate, calculated as annual rate ÷ 100 ÷ 12.
• n: Scheduled number of payments, calculated as years × 12.

For example, a $32,000 loan at 6% for three years uses r = 0.06 ÷ 12 = 0.005 and n = 36. The regular payment is about $973.50. First-month interest is $160.00, leaving about $813.50 to reduce principal. As the balance declines, the interest charge declines too.

The schedule keeps calculation values at full precision and rounds displayed dollars for readability. The final payment is capped at the remaining balance plus that row's interest, so it may be smaller than earlier payments. A lender can show a different figure because of payment dates, daily interest, fees, or contract rounding.

At a zero interest rate, the regular payment is principal divided by the number of periods. With an extra payment, the model adds that amount each month and applies it to principal, which shortens the schedule when the balance reaches zero.

The OpenStax Principles of Finance 2e describes the same fixed-payment approach: convert the annual rate and term to monthly values, then separate each payment into interest and principal.

For a focused view of how extra payments alter the payoff timeline, use the Loan Repayment Calculator alongside this detailed schedule.

These terms make the table easier to read and help keep comparisons consistent.

A fixed payment does not have a fixed split. The payment can remain level while the interest portion falls and the principal portion rises. Total paid in this model is principal plus modeled interest; it does not include taxes, insurance, origination charges, or other costs outside the entered balance.

The Consumer Financial Protection Bureau explains that a fixed-rate mortgage payment can stay steady while the shares assigned to principal and interest change. That is the pattern shown in the monthly rows here.

For a vehicle purchase where taxes, trade-in value, and amount financed matter, the Auto Loan Calculator provides more specific purchase inputs than this general schedule.

Use the figures that describe the loan itself, not the whole household payment. Keep the amount, rate definition, and term consistent when you compare scenarios.

1. 1 Enter the loan amount: Type the original principal, such as $32,000 for a car or $200,000 for a mortgage. Include a fee only if it was financed. Do not add taxes or insurance that you pay separately.
2. 2 Enter the note rate: Use the fixed interest rate in the promissory note, such as 6.5 for 6.5%. APR and note rate are not interchangeable. APR can include certain finance charges and is intended for offer comparison, while this formula needs the periodic interest rate used to accrue the loan. If you enter APR, label the result as an approximation and verify it against the disclosure.
3. 3 Choose the term: Enter whole years. A 30-year term creates 360 monthly periods. For a shorter term, expect a higher required payment but usually less lifetime interest.
4. 4 Test extra payment: Enter a recurring monthly amount only when you want to model the same additional principal payment every month. Use zero for the ordinary schedule.
5. 5 Read the result: Review payment, total interest, total paid, payment count, and the extra-payment comparison before reading the detailed rows.

How to read the yearly rows: Each row totals the monthly activity for that year. Principal and interest add to total paid for the row, while ending balance is the balance after the last payment in that year. Use this view to compare progress at year five, ten, or another milestone without scanning every payment.

How to read the monthly rows: Payment is the amount charged in that row, followed by the part reducing principal, the interest charge, and the balance after payment. Check the first row to understand the starting split, a middle row to see the trend, and the last row to see the payoff adjustment. Use this amortization calculator to compare those rows with the loan statement you receive.

As a simple test, run $200,000 at 6.5% for 30 years with no extra payment. Record total interest and the year-five balance, then enter $200 extra. Compare the changed payment count, interest saved, and ending rows.

A schedule gives context to the monthly payment and helps compare repayment choices.

• • See lifetime cost: Total interest and total paid show the price of the selected rate and term, not just the amount due each month.
• • Measure balance progress: Yearly ending balances show how quickly debt declines and provide checkpoints for a refinance, sale, or payoff plan.
• • Compare terms: Run the same amount and note rate at 15, 20, and 30 years. The shorter term usually raises the monthly obligation but reduces the number of interest-bearing periods. Compare both payment fit and total interest.
• • Evaluate extra payments: Interest saved and months saved show the modeled value of a recurring additional amount, subject to the lender's rules.
• • Check assumptions: A monthly row can show a final-payment change, an unexpectedly quick payoff, or a balance pattern that deserves comparison with the lender's statement.

Change one input at a time. Compare the same loan with and without extra money, or compare two terms while holding the amount and rate constant. If you change the rate, amount, and term together, the output cannot show which decision caused the change.

Before prepaying, check for a minimum amount, penalty, recast rule, or principal-only instruction. The savings shown here come from lower modeled interest and do not subtract a lender charge.

If the goal is an early mortgage payoff, the Mortgage Payoff Calculator provides a more focused comparison of payoff timing and extra payments.

The displayed schedule is a fixed-rate estimate. These inputs and contract details can change the result or make a lender's statement differ from the model.

• • The estimate assumes a fixed rate, monthly payments, no missed payments, and no new fees. It does not model adjustable-rate resets, interest-only periods, balloon payments, revolving credit, or negative amortization.
• • For a mortgage, the displayed amount covers modeled principal and interest only. Property taxes, homeowners insurance, mortgage insurance, escrow changes, and closing costs can make the actual payment higher.
• • The last row is adjusted to pay the remaining mathematical balance. Because values are calculated before display rounding, the final payment may not equal earlier displayed payments. A servicer may also use daily interest, posting dates, fees, or a different rounding convention.

A lender's payoff quote is tied to a date and can include interest accrued since the last payment. Use the contract and servicer statement for an actual payoff or prepayment decision.

The Consumer Financial Protection Bureau notes that amortization shows how payments are divided between principal and interest, and that a longer auto-loan term can reduce the payment while increasing total interest.

For several mortgage prepayment patterns instead of one recurring monthly amount, use the Mortgage Prepayment Calculator to compare the modeled effect.