Loan Amortization Calculator

Because interest is charged on what you still owe, and at the start you owe almost everything. The monthly interest is the balance times the monthly rate, so on a 250,000 loan at 6 percent the first month's interest alone is 1,250. Your payment is fixed, so whatever is left after that interest goes to principal, which early on is very little. As the balance falls, the interest portion falls with it and the principal portion grows, which is why the curve accelerates in the later years.

Not directly; there is no extra-payment field. You can approximate it by shortening the term and seeing what the payment becomes, which tells you what you would need to pay to clear the loan in, say, 25 years instead of 30, and how much interest that saves. The saving is usually far larger than people expect.

Rounding conventions and day counts. This calculator uses the annual rate divided by 12 for every month, whereas some lenders use a daily rate applied to the actual number of days in each month, and they may round each installment differently. The difference is normally a few units per payment. The shape of the schedule is right even if the last decimal is not.

Yes. The annuity formula would divide by zero at a rate of 0, so that case is handled separately by dividing the principal evenly across the number of months. Every payment is then identical, all of it principal, and the total interest is zero.

Copy schedule (CSV) puts the whole payment-by-payment table on your clipboard with a header row of Payment, Amount, Principal, Interest, Balance, and with the thousands separators stripped so every value lands in its own cell. Paste it into a spreadsheet to chart the principal-versus-interest crossover, or to model what an overpayment would do.