Student loan extra payment calculator

How this calculator works

This calculator runs your student loan balance forward month by month twice: once with your current payment and once with your current payment plus the extra amount. Each month, interest is the balance times one twelfth of the yearly rate, and the rest of the payment lowers the balance. Enter the rate shown on your own loan statement. The tool compares the two runs to show how much sooner you finish, how much interest you save and your new debt-free date.

Assumptions: one loan with one fixed rate, and the same payment every month. If you have several loans, you can enter a combined balance with a blended rate, but the result will be rough. Income-driven plans, forgiveness, deferment, forbearance and unpaid interest added to the balance are not modeled. If your payment does not cover the monthly interest, the tool says so instead of showing a date.

How this affects buying a home: lenders count student loans in your debt-to-income ratio. Depending on the program, they may use the payment on your credit report or a payment calculated from your balance, especially if the loans are deferred or on an income-driven plan. A lower balance can lower a calculated payment. Extra payments also use cash that could go toward a down payment or reserves, so ask a loan officer how your loans will be counted before you decide.

Example: enter a $30,000 balance, the rate and payment from your statement, and $100 extra a month.

Related: Debt-to-income calculator · Debt-free date calculator · Loan payment calculator