Amortization Schedule Calculator
Enter the loan amount, interest rate, and term for any installment loan, auto, personal, student, or otherwise, to see the complete month-by-month breakdown of principal and interest until it's paid off. Add an optional extra monthly payment, or switch to biweekly, to see how much sooner the balance reaches zero.
Summary
| Monthly payment | - |
|---|---|
| Total interest paid | - |
| Total paid | - |
| Months to payoff | - |
Principal vs. interest paid over time
Cumulative dollars that have gone to principal versus interest, at each year-end.
Full amortization schedule
Every payment from month 1 to payoff, in order. Scroll within the table to see the whole thing.
| Month | Payment | Principal | Interest | Balance |
|---|
Understanding amortization schedules
An amortization schedule is the row-by-row record of how a fixed-payment loan gets paid off. It applies to almost any installment loan: a car loan, a personal loan, a student loan, or any debt you repay in equal regular installments over a set number of months. Every one of those payments is split into two parts. The first part is interest, which the lender charges on whatever balance you still owe. The second part is principal, the portion that actually reduces that balance. The schedule tracks, month by month, how much of each payment goes to each part and how much you still owe afterward. Reading it is the difference between knowing what a loan costs per month and knowing what it costs in total.
How the payment and the split are computed
The fixed payment is the one amount that, paid every period at your interest rate, pays the balance down to exactly zero on the final payment. It comes from the standard amortization formula, which uses three inputs: the loan amount, the periodic interest rate (your annual rate divided by 12 for a monthly loan), and the number of payments. Once that payment is fixed, the calculator walks the loan forward one month at a time. In each month it first charges interest on the current balance, then treats the rest of the payment as principal, and subtracts that principal from the balance to get the figure that carries into the next row. Because the payment is flat but the balance it is charged against keeps shrinking, the interest-versus-principal split changes every single month.
How the split shifts over the life of the loan
The most important pattern to notice in the table above is that the split moves steadily even though the payment never changes. In month one the balance is at its highest, so interest claims its largest share and the principal portion is at its smallest. Each month after that, the balance is a little lower, so a little less of the payment is needed to cover interest, and a little more goes to principal. The effect accelerates gently toward the end, where the last several payments are almost entirely principal. The chart on this page makes the trend visible: the cumulative-interest line rises quickly at first and then flattens, while cumulative principal climbs steadily until it reaches the full loan amount at payoff. This is why paying a loan down early is so much more powerful than paying it down late.
A worked example
Take this calculator's defaults: a $25,000 loan at a fixed 7% annual rate over 5 years, which is 60 monthly payments. The monthly interest rate is 7% divided by 12, or about 0.583%. The formula produces a fixed payment of about $495.03. In the first month, interest is roughly 0.583% of $25,000, about $145.83, so only about $349.20 of that first $495.03 goes to principal. By the final payments almost the entire $495.03 is principal, because the balance left to charge interest on is tiny. Add up all 60 payments and you pay about $29,702 in total, of which about $4,702 is interest. That total-interest figure is the real cost of borrowing, and it is invisible if you look only at the $495 monthly number.
How extra payments and biweekly schedules cut interest and time
Two simple options can meaningfully shrink both the total interest and the number of months to payoff. The first is an extra monthly payment. An extra amount does not change what the schedule requires of you; it is applied on top of the normal payment and goes straight to principal. That lowers the balance faster than the plain schedule assumes, which in turn lowers every future interest charge, so the loan ends early and the table below gets shorter. The second option is paying biweekly. Instead of twelve monthly payments you pay half the monthly amount every two weeks. There are 52 weeks in a year, so that is 26 half-payments, equal to 13 full payments a year rather than 12. That one additional payment each year goes entirely to principal. This calculator models biweekly by adding one-twelfth of the base payment to every month as extra principal, which closely matches the true biweekly payoff date. Either approach works for the same reason: every dollar of principal you retire early is a dollar you stop paying interest on for the rest of the loan. Even a modest extra can remove a surprising amount of interest, especially early in the term when the balance is largest.
Common mistakes to avoid
- Budgeting off the monthly payment alone. A payment you can afford is not the same as a loan you can afford. Always look at the total interest and total paid before you sign, not just the figure that leaves your account each month.
- Choosing a longer term just for the lower payment. Stretching a loan over more years lowers the monthly payment but raises the total interest, often substantially. Compare a shorter and longer term here and read the total-interest line for each before deciding.
- Overlooking prepayment penalties. Some loans charge a fee for paying off early, which can cancel out the savings from extra payments. Check your loan agreement before you commit to an accelerated payoff plan.
- Assuming extra payments go to principal automatically. Many lenders apply extra money to the next scheduled payment or to fees unless you tell them otherwise. Specify that any extra is to be applied to principal.
- Ignoring the opportunity cost. Paying a loan down early earns a guaranteed return equal to its interest rate, but it also ties up cash. Weigh it against a higher-rate debt, an emergency fund, or matched retirement contributions.
Frequently asked questions
What is an amortization schedule?
It is a table that lists every payment on a fixed-payment loan in order, showing how much of each payment goes to interest, how much goes to principal, and the balance remaining afterward. It lets you see exactly how a loan is paid off from the first month to the last, and what it costs in total interest along the way.
Why does most of my early payment go to interest?
Interest is charged on the balance you still owe, and that balance is highest at the start of the loan. So in the early months the interest charge is large and the leftover principal portion is small. As the balance falls, the interest charge falls with it and more of each fixed payment goes to principal, which is why the last payments are almost all principal.
Does this calculator work for auto, personal, and student loans?
Yes. The math is the same for any installment loan with a fixed rate and a fixed term, so you can use it for auto loans, personal loans, student loans, and similar debts. Enter the loan amount, the annual interest rate, and the term in years, and the schedule and totals update instantly.
How much do extra payments actually save?
It depends on your rate, term, and balance, but the savings are often larger than people expect because every dollar of principal retired early stops accruing interest for the rest of the loan. Enter an extra monthly amount, or switch the frequency to biweekly, and the total interest and months-to-payoff figures above will show your exact result.
Are these numbers an exact quote?
No. This is an educational estimate based on a single fixed rate and no fees. Your real loan may include origination charges, insurance, a variable rate, or a different compounding method, all of which change the figures. Use this to understand the trade-offs, then rely on your lender's official disclosure for exact numbers.