Extra Payment Calculator

Extra Payment Calculator

Paying more than your required payment is one of the simplest ways to get out of debt faster and cheaper. Every extra dollar goes straight to your principal, which shrinks the balance that future interest is charged on. This calculator shows how much interest and time you would save by paying a little extra each month, a one-off lump sum now, or both.

Assumptions & Limitations

This calculator assumes a loan with fixed, equal monthly payments and interest compounded monthly — the norm for most personal loans, auto loans and mortgages in the United States. It assumes every extra payment goes entirely toward your principal and that your lender applies it immediately with no prepayment penalty. Some lenders charge a fee for paying early or apply overpayments only at certain times, so check your loan agreement before relying on these numbers. A lump sum is treated as a single payment made today.

Calculator Inputs

• Loan amount: The amount you borrowed, or your current balance if you are partway through the loan.
• Interest rate: The annual interest rate on the loan. The higher the rate, the more you stand to save by paying extra.
• Loan term: The original length of the loan, in years or months. This sets your normal monthly payment, which is the baseline the savings are measured against.
• Extra per month: An amount you pay on top of your normal payment, every month. Even a small amount adds up over the life of a loan.
• One-off payment now:A single lump sum applied to your balance today — for example, from a bonus or tax refund.

Understanding Your Results

The summary highlights your two headline savings: how much sooner you would be debt-free, and how much interest you would avoid. Beneath it, a table compares your loan with and without the extra payments:

• Payoff time: How long until the loan is fully repaid in each case.
• Total interest:The interest you pay over the life of the loan in each case — the gap between the two is your interest saving.
• Monthly payment: Your normal payment versus your normal payment plus the extra monthly amount.

Because the savings come from reducing your balance early, the biggest gains come on higher-rate loans and from paying extra as soon as possible. If your loan has no prepayment penalty, even an occasional overpayment in months you have spare cash will move your payoff date forward.