Student Loan Calculator

Understanding student loan repayment

Student debt behaves differently from most other loans because of when interest starts, how repayment is structured, and the protections attached to federal loans. This calculator models the most common scenario — a fixed-rate loan repaid in equal monthly installments — so you can see your payment, total interest, payoff date, and a month-by-month schedule. But the number on the screen only tells the full story once you understand the rules around it, so the sections below walk through the concepts that decide what you really owe.

The first fork in the road is whether your loans are federal or private. Federal loans come with fixed rates set by law and carry borrower protections — income-driven repayment, deferment, forbearance, and potential forgiveness programs — that private loans generally do not. Private loans are issued by banks and other lenders, may carry fixed or variable rates, and are priced on your (or a cosigner's) credit. The cheaper headline rate on a private loan can be tempting, but it usually comes without the safety nets federal borrowing provides.

How to use this calculator

Enter your total loan balance, or the balance of a single loan you want to model, then the fixed interest rate and your repayment term in years. The calculator returns a fixed monthly payment, the total interest over the life of the loan, your payoff date, and a downloadable schedule. An optional extra-payment field shows how paying more each month accelerates payoff — federal loans never carry a prepayment penalty, so every extra dollar goes straight to principal.

How the payment is calculated

A standard repayment plan is fully amortizing, so it uses the familiar formula M = P · r / (1 − (1 + r)^−n), where P is the balance, r is the monthly rate (annual rate ÷ 12), and n is the number of payments. Each month, interest accrues on your current balance and is paid first; the rest reduces principal. Standard federal repayment is typically structured over ten years, which keeps total interest relatively low compared with plans that stretch payments out further.

Subsidized vs unsubsidized, capitalization, and the grace period

Two big concepts drive how much you ultimately repay. First, subsidized vs unsubsidized: on a subsidized loan, the government pays the interest while you are in school and during certain deferment periods, so the balance does not grow during those times. On an unsubsidized loan, interest accrues from the day the loan is disbursed — even while you are still studying. Second, the grace period: federal loans typically give you a window after leaving school before payments are due. That sounds generous, but on unsubsidized loans interest keeps building during the grace period, and any unpaid interest can be capitalized — added to your principal — when repayment begins. After capitalization you start paying interest on interest, which quietly enlarges the loan. Paying even small amounts toward interest while in school or during the grace period prevents that.

A worked example

Suppose you owe $30,000 at a hypothetical 6% fixed rate. On a ten-year standard plan the payment is about $333 a month and total interest comes to roughly $9,970. Stretch the same balance over twenty years and the payment falls to about $215 — much easier early in a career — but total interest more than doubles to around $21,580. The lower payment is real relief, but it is bought with a great deal of extra interest.

Based on a hypothetical $30,000 balance at 6%; figures are illustrative only.

Repayment plan types

Federal borrowers usually have several plan styles to choose from, and they change the shape of your payments rather than the underlying loan. A standard plan keeps payments level over a fixed term. A graduated plan starts payments low and steps them up over time, on the assumption your income will rise. Income-driven plans cap your payment at a share of your discretionary income and can stretch the term considerably, sometimes ending in forgiveness of any remaining balance. Because graduated and income-driven payments change over time, this calculator models the standard plan as a clean baseline; treat it as a reference point for the others.

Refinancing, deferment vs forbearance, and tips

Refinancing replaces one or more existing loans with a new private loan, ideally at a lower rate. The trade-off is stark for federal borrowers: once refinanced into a private loan, those federal protections are gone for good. If your income is stable and your credit is strong, the interest savings can be substantial; if your career or income is uncertain, the safety nets may be worth more than the rate cut. Separately, when you cannot pay, deferment and forbearance both pause payments, but they differ on interest: during deferment, the government may cover interest on subsidized loans, while during forbearance interest generally keeps accruing on all loans and can later be capitalized. A few practical habits help:

• Pay interest while in school on unsubsidized loans to stop capitalization from enlarging your balance.
• Compare total interest, not just the monthly payment, when choosing a repayment length.
• Think hard before refinancing federal loans; the protections you give up cannot be bought back.
• Make extra payments toward the highest-rate loan first if you hold several at different rates.