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Loan payment & amortization schedule calculator

Understand the cost of a fixed-rate loan.

  • Formula and assumptions shown
  • Table and CSV export
  • Runs in your browser

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Inputs

$USD
%
years

Results update as you type. Amounts in USD. Rates are nominal annual rates.

Result

Ready to calculate

Calculated result—

Enter your numbers to see an estimate.

Assumptions and methodology

How it works

The monthly payment is calculated from the principal, nominal annual rate, and number of monthly payments. Each modeled payment first covers that month's interest, then reduces principal; the final payment may be smaller when the balance is nearly paid off.

The schedule keeps full precision internally and rounds values only when displayed. This avoids creating an artificial leftover balance from rounding every month.

Read the schedule for how the interest share changes. The first payment is charged interest on the full balance, so interest takes its largest share then; by the final months almost the whole payment reduces principal. A longer term lowers the payment but spreads interest over more months, so compare total interest as well as the monthly amount.

Read the full methodology

Assumptions

  • The loan has a fixed nominal annual rate applied as annual rate divided by 12.
  • Payments occur monthly and are scheduled evenly across the selected term.
  • Each payment covers that month's interest before principal, consistent with a standard amortizing loan.
  • The base model excludes origination fees, taxes, insurance, penalties, adjustable rates, payment holidays, and lender-specific rules.

Worked example

$25,000 at 7% for 5 years

The estimated monthly payment is $495.03. The first payment includes $145.83 of interest ($25,000 × 7% ÷ 12). Over 60 payments, the modeled total is $29,701.80, of which $4,701.80 is interest.

Step by step

  1. Convert the rate and term. The 7% annual rate is divided by 12 for a monthly rate of 0.5833% (0.07 ÷ 12 = 0.0058333), and 5 years becomes n = 60 monthly payments.
  2. Compute the growth factor. (1 + 0.0058333)^60 = 1.41763, the amount $1 would grow to over 60 months at the monthly rate.
  3. Solve for the payment. Payment = $25,000 × 0.0058333 × 1.41763 ÷ (1.41763 − 1) = $495.03. The same payment repeats in every month of the term.
  4. Split the first payment. Month 1 interest is $25,000 × 0.5833% = $145.83, so $495.03 − $145.83 = $349.20 goes to principal and the balance falls to $24,650.80.
  5. Follow the schedule to the end. Interest shrinks as the balance falls: the first 12 payments carry $1,612.91 of interest in total, while the 60th payment carries only $2.87.
  6. Add up the totals. Sixty payments of $495.03 come to $29,701.80 (the schedule sums unrounded payments). Subtracting the $25,000 borrowed leaves $4,701.80 of interest.

How to read your result

The headline is the estimated monthly principal-and-interest payment. Below it, total paid is every scheduled payment added together, total interest is the part of that total above the amount borrowed, and time to payoff equals the term you entered. The donut splits the total paid into principal and interest.

The schedule table lists each month’s payment, its interest portion, and the balance left afterward; the chart plots that balance. The line bends because interest is charged on a falling balance: in the example, interest is about 29% of the first payment and under 1% of the last, so the balance drops slowly at first and faster near the end.

The payment excludes origination fees, sales tax, insurance, property tax, late fees, and rate changes. If a lender quotes an APR above the note rate, the gap usually reflects fees that this calculation leaves out; the APR calculator estimates that effect. Lenders that charge interest daily or set a different first-payment date can produce a payment that differs by a few cents or dollars.

What changes the result most

Interest rate
On $25,000 over 5 years, 6% gives $483.32 a month and $3,999.20 of interest, while 8% gives $506.91 and $5,414.59. Each percentage point moves the payment by about $12 and total interest by about $700 on this loan.
Term length
At 7%, a 3-year term costs $771.93 a month and $2,789.39 of interest. A 7-year term lowers the payment to $377.32 but raises interest to $6,694.63, about 2.4 times the 3-year total.
Amount borrowed
The payment scales in direct proportion to the amount. Borrowing $26,000 instead of $25,000 at 7% for 5 years raises the payment by $19.80 to $514.83 and total interest by $188.07.

Questions

Why does the interest share change over time?

Interest is calculated from the remaining balance. Early payments start with a larger balance, so more of the payment goes to interest; as principal falls, more goes to principal.

Does this include taxes or insurance?

No. The result models principal and interest only. For a home loan, the mortgage payment calculator adds the property tax, insurance, HOA, and PMI amounts you enter. For other loans, add separate charges outside the payment shown here.

Why might my lender's payment differ?

Lenders may use daily interest, fees, different rounding, a different payment date, or an adjustable rate. Check your disclosure and use this result as an estimate.

How is interest on a loan calculated?

On a standard amortizing loan, each month’s interest is the remaining balance times the monthly rate, which is the annual rate divided by 12. In the example, the first month is $25,000 × 7% ÷ 12 = $145.83. Because the payment is fixed and the balance falls, each later payment carries less interest. Some lenders accrue interest daily instead, using the annual rate divided by 365 or 360 and the days between payments, which shifts the figures slightly.

What is an amortization schedule?

It is a table of every scheduled payment on a loan, showing how much of each payment is interest, how much reduces principal, and the balance left afterward. The schedule on this page is built from the amount, rate, and term you enter, and it can be downloaded as a CSV file.

Does paying extra principal lower the monthly payment?

On a standard fixed-rate installment loan, usually not. Extra principal lowers the balance, so the loan ends sooner and costs less interest, but the scheduled payment stays the same unless the lender re-amortizes the loan (a recast). The extra payment calculator shows the time and interest saved; the mortgage recast calculator shows a lower payment after a lump sum.

More in Loans & debt

Sources

These references explain the concepts behind the calculation. They do not endorse this site. Estimates leave out any cost or condition you did not enter.