SumPersonal Loan Calculator
Plan a personal loan or a debt payoff. Enter the loan amount, APR and term, then add an optional extra monthly payment to see how much faster you become debt-free and how much interest you save.
Your monthly payment
How It Works
A personal loan is repaid in equal monthly installments over a fixed term. The monthly payment comes from the standard amortization formula, M = P × r(1+r)n / ((1+r)n − 1), where P is the amount borrowed, r is the monthly rate (APR divided by 12), and n is the number of monthly payments. Early on, most of each payment goes to interest; as the balance shrinks, more of it goes to principal. With a 0% APR, the payment is simply the loan amount divided by the number of months.
Extra payments are powerful because every extra dollar goes straight to the principal, which shrinks the balance that future interest is charged on. The calculator simulates your loan month by month with the extra payment applied, so you can see the real payoff date and the exact interest saved — not a rough guess.
Worked example: a $10,000 personal loan at 10% APR over 5 years (60 months) has a monthly payment of about $212.47, and you pay about $2,748.23 in total interest. Add an extra $50 a month and the loan is paid off in about 47 months instead of 60 — more than a year sooner — and total interest falls to about $2,081.33, saving you about $666.90. A small extra payment every month makes a big difference because it attacks the balance from the very first month.
Before making extra payments, check that your lender applies them to principal and does not charge a prepayment penalty. Most personal loans in the US allow extra payments without a penalty, but it is worth confirming, and always ask for the extra amount to be applied to principal rather than treated as an early payment of next month's bill.
Frequently Asked Questions
How much can extra payments really save me?
More than most people expect. Even $50 extra a month on a $10,000 loan at 10% APR saves about $667 in interest and cuts over a year off the payoff. The higher your APR, the more each extra dollar saves, because it avoids interest at that high rate.
Should I pay extra on my loan or save the money instead?
Compare the rates. If your loan charges 10% APR and your savings account pays 4%, paying down the loan earns you a guaranteed 10% return. But keep an emergency fund first — money paid into a loan is hard to get back in a crisis.
What is a good APR for a personal loan?
It depends on your credit score, income and loan size. Borrowers with strong credit typically get the lowest rates, while lower scores mean higher APRs. Compare at least three lenders, and watch for origination fees, which add to the true cost of the loan.
Does paying off a personal loan early hurt my credit score?
It can cause a small, temporary dip because you close an account and shorten your credit mix, but the effect is usually minor and short-lived. Being debt-free and saving hundreds in interest is almost always worth more than a few points on your score.
Can I use this calculator for credit card debt payoff?
Yes, as an estimate. Enter your card balance as the loan amount, the card's APR, and the monthly payment you plan to make as the extra payment on top of a small base term. Note that credit card interest compounds differently and minimum payments shrink as the balance falls, so treat the result as a guide rather than an exact figure.
Last updated: November 2026