Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
See how much time and interest you save by paying extra each month on an existing loan.
45 months
Adding even a modest extra amount to a monthly loan payment can meaningfully shorten a loan's payoff time and cut total interest paid, since every extra dollar goes straight toward principal rather than being split with interest. This calculator simulates your loan month-by-month both with and without an extra payment, showing the real difference rather than a rough estimate.
Enter your current remaining balance, interest rate, your current required monthly payment, and how much extra you'd add each month.
Each month, interest is calculated on the current balance, the remainder of the payment reduces principal, and the process repeats until the balance reaches zero -- once with your normal payment, once with your normal payment plus the extra amount, and the two results are compared.
Use this to decide whether putting extra cash toward a loan payment is worth it compared to other uses (like investing or building savings) -- the interest-saved figure is effectively your guaranteed "return" on that extra payment.
Suppose you have a hypothetical $20,000 balance at 6% and pay $400 a month. Simulating month by month, the loan takes about 58 months to clear and costs roughly $3,070 in interest. Adding $100 extra brings the payment to $500, and the loan finishes in about 45 months with roughly $2,370 in interest. That is about 13 months sooner and about $700 less interest. The exact amounts depend on your inputs, but the pattern holds: extra payments help most when applied early, while the balance is highest.
If you have several debts, the calculator shows the effect for one at a time, so run it for each and compare the interest saved. Higher-rate debts usually deliver larger savings for each extra dollar. Before deciding, check for prepayment penalties in your loan agreement, which are less common on consumer loans but do exist on some products, and confirm that your lender applies extra money to principal.
The simulation treats each payment as arriving exactly once a month and interest as accruing monthly. Some lenders calculate interest daily, so your actual results may be slightly different. It also does not model a rate that changes, fees for late payments, or one-time lump sums. If you plan a large single payment instead of regular extras, the total effect is similar in direction, and you can approximate it by lowering the starting balance.
Being debt-free earlier also lowers your monthly obligations and can improve your debt-to-income ratio. But paying extra means less cash for emergencies, so make sure you already have some savings set aside first. Balance this against any employer retirement match, which many people prioritize because it is effectively additional compensation. A licensed financial advisor can help if the tradeoffs are unclear.
Confirm with your specific lender -- most standard loans apply any amount beyond the required payment directly to principal, but some loans or servicers require you to explicitly designate extra payments as "principal only," so check your loan's specific process.
Not necessarily -- compare your loan's interest rate against what you could earn investing that money instead; extra payments make the most sense on higher-interest debt, while low-rate debt may be worth carrying while investing elsewhere.
Then the balance will not decline, and the result will not be meaningful. Double-check your balance, rate, and payment, or increase the payment.
Both reduce principal. Earlier payments save more interest, so a lump sum applied now typically has a bigger effect than the same money spread out over a year.
Usually not. The required payment stays the same, but the loan finishes earlier. Confirm the process with your lender.
Reference: Consumer Financial Protection Bureau