Loan Payment Calculator
Compute the regular monthly payment for an entered loan balance, fixed annual interest rate and number of months. Extra monthly payments are added after the regular payment is calculated.
Use the nominal annual interest rate, excluding fees. A disclosed APR that includes fees is not necessarily the nominal rate used in this model.
Free to use, with no sign up. Calculations run in your browser; entries are not uploaded.
Result
P = entered principal − down payment; i = annualRatePercent / 1200; n = term in months. Regular payment M = P × i / [1 − (1 + i)^(−n)]. At 0%, M = P / n. Monthly interest = previous balance × i; principal repaid = actual payment − interest; new balance = previous balance − principal repaid. Total payments = P + total interest.
Primary source: OpenStax Principles of Finance: loan amortization, the present value of an ordinary annuity rearranged for monthly payment. This calculator uses nearest-cent, half-up rounding for both payments and monthly interest.
Worked example: With $100 at 12% annually for 2 months, i = 12/1200 = 0.01 and M = 100 × 0.01 × 1.01² / (1.01² − 1) = $50.75 after rounding. Month one has $1.00 interest and $49.75 principal, leaving $50.25. Month two has $0.50 interest and clears the balance with $50.75. Total interest is $1.50. At 0%, $1,200 over 12 months is $100.00 per month.
Monthly payment table
Model bounds: positive financed balance; monetary inputs up to $100,000,000 with at most two decimal places; annual rate from 0% to 100% with at most six decimal places; 1–360 whole months. All periods are equal months, with the first payment after one month. The schedule has at most 360 rows. Payments stop at zero balance. A formula payment below one cent becomes one cent; the final period clears any rounding residue. Totals exclude the down payment and include loan payments only. Fees, penalties and changing rates are excluded.
How to use this tool
Enter amounts in USD, the fixed nominal annual interest rate as a percentage and a whole-month term. Select Calculate to update the payment, totals and period table. Enter zero for no extra monthly payment.
Frequently asked questions
How are cents and the final payment handled?
Money inputs accept at most two decimal places. Payment and each monthly interest charge round to the nearest cent, with exact half cents rounded upward. The last payment clears the remaining balance and interest, so it may differ from the regular payment.
What happens at a zero interest rate?
The regular payment is financed principal divided by the entered months, rounded to cents with a one-cent minimum. Each payment reduces principal only, and the last payment clears the remaining cents.
How do extra monthly payments affect the schedule?
The regular payment is computed from the financed principal, rate and original entered term. The extra amount is added each month and reduces the balance sooner. Payments stop when the balance reaches zero; a final short payment includes only the remaining balance and interest.