Loan Payoff Calculator
Enter your current balance, interest rate, and the monthly payment you're actually making (or plan to make) to see how long payoff will take and how much interest you'll pay along the way. Add an optional extra monthly payment and the calculator will compare the two plans side by side, showing exactly how much interest and how many months the extra buys you.
Results
Comparing paying just your stated payment against paying it plus the extra amount.
| Stated payment | With extra | |
|---|---|---|
| Monthly payment | - | - |
| Payoff time | - | - |
| Total interest paid | - | - |
| Total paid | - | - |
Add an extra monthly payment above to see how much interest and time you'd save.
Balance over time
Payoff schedule (with extra)
Showing year-end rows for readability.
| Month | Payment | Principal | Interest | Balance |
|---|
Paying off a loan when you already know your payment
Most loan math runs in one direction: you fix a term, say three or five years, and a formula hands you the fixed payment that clears the balance exactly on the last month. This calculator runs that math in reverse. You already know your payment, because it is whatever you choose to send on a credit card, a personal loan, or a line of credit that never came with a stated term. What you do not know is the thing a fixed term would have told you: how many months it will take, and how much interest you will hand the lender. Those answers are not written into the loan anywhere. They fall out of just three numbers, your balance, your rate, and your payment, and the moment you change any one of them, both answers move.
How payoff time and total interest are derived
The engine behind this page simply walks your loan forward one month at a time. Each month it charges interest on the balance you currently owe, using your annual rate divided by twelve. On a loan at 15 percent, that monthly rate is 1.25 percent, so an $8,000 balance accrues $100 of interest in the first month. Your payment covers that interest first, and whatever is left over is subtracted from the principal. Next month the interest is charged on the new, slightly smaller balance, so a few more of your dollars reach principal. The calculator repeats this until the balance hits zero, counts the months it took, and adds up every interest charge it posted. That count is your payoff time, and that sum is your total interest.
The key consequence is that the split between interest and principal is never fixed. Your payment stays flat, but because the balance keeps shrinking, the interest slice of each payment shrinks with it and the principal slice grows. Payoff therefore speeds up on its own as you go, even though you never change what you send. The declining-balance curve starts shallow and steepens toward the end, which is the shape you see in the chart above once numbers are entered.
Why your payment has to beat the monthly interest
There is a floor your payment must clear before any progress happens. If your payment is smaller than the interest that accrues in a month, the leftover interest is added to the balance and you owe more than before. The balance climbs instead of falling, and no number of payments will ever clear it. This break-even point is simply the balance multiplied by the monthly rate: for $8,000 at 15 percent it is that same $100 a month, and anything at or below $100 never pays the loan off. This is why the calculator refuses to print a payoff time in that case. Instead of a misleading result, it warns you and states the minimum payment needed just to hold the balance steady. Every dollar you pay above that break-even figure is the only part of your payment that actually retires debt.
A worked example: $8,000 at 15 percent, paying $250
Load the default numbers and watch what happens. You owe $8,000 at 15 percent and send $250 a month. The first month, $100 is interest and $150 comes off the balance. Because your $250 comfortably clears the $100 break-even, the loan pays off in about 3 years and 6 months, and over those payments you hand the lender roughly $2,280 in interest on top of repaying the $8,000. Now type 100 into the extra-payment field, sending $350 a month. The payoff time drops by more than a year and the interest total falls by roughly $800. You added only $100 a month, yet saved far more, because every extra dollar comes straight off the balance while the balance, and the interest it throws off, is still near its peak. The same $100 added in the final months would save almost nothing.
How extra payments accelerate the whole schedule
The comparison table and the balance chart make that effect visible rather than theoretical. The calculator runs your loan twice: once with just your stated payment, and once with the stated payment plus your extra. It lists both payoff times, both interest totals, and the difference between them in the callout, then draws both declining balances on the same axes so you can see the accelerated line pull away and reach zero sooner. The gap widens because compounding works in your favor: a smaller balance accrues less interest next month, leaving more of your flat payment for principal. The payoff schedule below and the CSV download both follow the accelerated plan.
Common mistakes to avoid
- Paying only the stated minimum. On revolving debt the minimum is designed to stretch repayment out for years. Sending even a small fixed amount above it, and holding that amount steady instead of letting it fall as the balance drops, is what actually ends the loan.
- Not knowing your break-even payment. If you have never worked out the balance times the monthly rate, you may be paying just above interest and barely moving. Check the figure here so you know how much of your payment is real progress.
- Trusting a credit-card minimum to cover much interest. Card minimums are often only slightly more than the month's interest, so almost nothing reaches principal and the balance lingers for a decade or more. A fixed payment you set yourself behaves far better.
- Waiting to pay extra. Extra money is most powerful early, when the balance and its interest drag are highest. Delaying it gives up most of the benefit.
Frequently asked questions
Why does the term change when I change my payment?
Because the term is not fixed in this kind of loan. The payoff time is derived from your balance, rate, and payment by stepping through the loan month by month until the balance reaches zero. A larger payment retires principal faster, so the count of months falls; a smaller payment does the opposite. That is the reverse of a mortgage, where you fix the term and the payment is derived from it.
What does the break-even warning mean?
It means your payment is too small to cover the interest that accrues each month, so the balance would grow rather than shrink and the loan would never pay off. The warning shows the minimum payment, your balance times the monthly rate, that you would need just to hold the balance steady. Anything above that figure starts reducing principal.
How much can an extra payment really save?
Often far more than the extra itself, especially early on. With the default $8,000 at 15 percent paying $250, adding $100 a month cuts the payoff by more than a year and saves roughly $800 in interest. Enter your own extra amount above and the calculator shows your exact interest saved and months shaved off.
Does this include fees, penalties, or a changing rate?
No. The calculator assumes a single fixed annual rate and no fees. Real loans may carry annual fees, late penalties, promotional or variable rates, or different compounding, any of which will shift the result. Treat the output as a clear illustration of how balance, rate, and payment interact, not an exact statement of your account.
Should I pay this loan off faster or invest the money instead?
Paying down a loan gives you a guaranteed return equal to its interest rate, which on high-rate debt like a 15 percent card is hard to beat elsewhere. Lower-rate loans are a closer call against investing or building an emergency fund. The tool shows the interest you would save, which is one side of that trade-off; weigh it against your other goals.