Loan Calculator: Monthly Payment & Amortization Schedule

For equal monthly payments made at the end of each interest period, the standard amortizing-payment formula is:

M = P × i / (1 - (1 + i)^(-N))

P is principal, i is the stated annual nominal percentage rate divided by 100 and then by 12, and N is the term in whole months. At 0% interest, M = P / N. The formula sets a regular principal-and-interest payment, not a minimum payment or an interest-only payment.

Money inputs, monthly interest, and the regular payment are rounded to cents using half-up rounding. The final payment clears the remaining balance and can be higher or lower. Totals are sums of the actual cent-rounded schedule, not the regular payment multiplied by the term.

A $10,000 loan at a fixed 12% annual nominal rate for 12 months has a regular monthly payment of $888.49 under this model. Month one includes $100.00 interest and $788.49 principal, leaving $9,211.51. The final payment is $888.47. Total repayment is $10,661.86, including $661.86 interest.

With a 2% origination fee withheld, the fee is $200.00 and net proceeds are $9,800.00. Payments and interest stay the same because the full $10,000 principal is still owed. Total borrowing cost is $861.86: interest plus the withheld fee. This is not a disclosure APR calculation.

The amortization schedule lists every payment. Each row shows the interest for that month, the part of the payment that reduces the principal and the balance left after the payment.

Interest makes up a larger share of earlier payments than later payments because the outstanding balance is higher. In the $10,000 example at 12% for 12 months, the first payment of $888.49 is $100.00 interest and $788.49 principal. The second payment is $92.12 interest and $796.37 principal, leaving $8,415.14. By the final payment almost all of it goes to principal.

Add a loan start date to see the calendar month of each payment, or leave it blank for a numbered schedule.

The stated interest rate determines the interest in this schedule. APR is a broader borrowing-cost measure that can include certain finance charges. This calculator does not determine which charges must be included under lending disclosure rules or compute a legally compliant APR. Use the stated interest rate and review the lender's separate disclosures.

The optional fee is either a fixed USD amount or a percentage of original principal. It is withheld once from proceeds. It is not financed, does not reduce the loan principal, and does not change the scheduled payments. Do not add it to total repayment a second time when comparing the schedule with the money you receive.

To estimate how an origination fee raises the cost of borrowing as an annual rate, use our APR calculator with the same loan details.

The start date is optional. If entered, the first payment is one calendar month later, on the original day or the last valid day of that month. Each later date is anchored to the original day, avoiding month-end drift. Interest assumes equal monthly periods regardless of calendar length; daily accrual and irregular first periods are not modeled.

Supported inputs are principal up to $1 billion, an annual nominal rate from 0% to 100% with six decimal places, and 1 to 600 months. The fee must leave positive net proceeds. Plans with sub-cent regular payments, no principal reduction after rounding, dates beyond year 9999, or a rounding-induced final payment more than twice the regular payment are not supported.