Student Loan Calculator
See what a student loan really costs and how fast you can clear it. Get your monthly payment, total interest, and full payoff breakdown, then add an extra monthly payment to see the time and interest you would save. A projection mode estimates the balance you will owe after borrowing through school.
Formula
Worked example
A 30,000 balance at 6.53% over 10 years: r = 0.0653 / 12 = 0.005442, n = 120. M = 30000 x 0.005442 x 1.005442^120 / (1.005442^120 - 1) is about 341.10/month, so total paid is about 40,932 and total interest about 10,932. Adding 100/month extra clears it roughly 25 months early and saves over 2,000 in interest.
How student loan repayment is calculated
A standard student loan is an amortizing loan: you make the same fixed payment every month, and each payment covers the interest accrued that month plus a slice of the principal. Early on, most of the payment goes to interest because the balance is large; as the balance falls, more of each payment chips away at principal. The fixed payment is set so the loan reaches exactly zero at the end of the term, which is why a longer term means smaller payments but far more interest paid overall.
Paying extra to clear the loan sooner
Any amount you pay above the required monthly payment is applied straight to principal, so it cuts the balance that future interest is charged on. Enter an extra monthly amount and the calculator re-solves the payoff: it shows your new total payment, how many months earlier the loan clears, and the interest you avoid. Because interest compounds on the outstanding balance, even a modest extra payment early in the term can save a striking amount, and it shortens the loan with no penalty on federal or most private student loans.
Projecting a balance from in-school borrowing
Switch to projection mode to estimate what you will owe once repayment begins. Enter how many years of school remain, how much you borrow each year, any balance you already carry, and your grace period. Unsubsidized loans accrue interest while you are in school and during the grace period; if you do not pay that interest, it capitalizes (gets added to principal), so you begin repayment owing more than you borrowed. Toggle on paying interest during school to see how much capitalization you avoid by covering interest as it accrues.
Why the interest rate and term matter so much
The total cost of a loan is driven by how much you owe, the annual interest rate, and how many years you take to repay. Two loans with the same balance can cost thousands apart depending on rate and term. Stretching repayment from 10 to 20 years roughly halves the monthly payment but can more than double total interest, because the principal accrues interest for twice as long. Refinancing to a lower rate or making extra principal payments are the two most effective ways to cut what you repay.
Federal versus private student loans
Federal student loans carry fixed rates set by Congress and come with protections like income-driven repayment, deferment, and potential forgiveness, features this calculator does not model since it assumes a fixed payment to full payoff. Private loans may offer variable or fixed rates and generally lack those federal safety nets. Before refinancing federal loans into a private loan to chase a lower rate, weigh the protections you would give up against the interest you would save.
How term length changes a 30,000 loan at 6.5%
| Term | Monthly payment | Total interest | Interest cost |
|---|---|---|---|
| 5 years | 587 | 5,200 | Low |
| 10 years | 341 | 10,900 | Moderate |
| 15 years | 261 | 17,100 | Moderate |
| 20 years | 224 | 23,700 | High |
Longer terms lower the monthly payment but sharply increase total interest.
Frequently asked questions
How is my student loan monthly payment calculated?
It uses the standard amortization formula. The monthly rate (annual rate divided by 12) and the number of months set a fixed payment that pays off the balance exactly at the end of the term. Each payment covers that month’s interest first, and the rest reduces your principal.
How much do I save by paying extra each month?
Enter an extra monthly amount in repay mode. Every extra dollar goes straight to principal, so the loan clears sooner and accrues less interest. The calculator shows the months saved and the total interest you avoid. Federal and most private student loans have no prepayment penalty, so extra payments always help.
What does the projection mode calculate?
Projection mode estimates the balance you will owe when repayment starts. It adds each year of new borrowing, then accrues interest through school and the grace period. If you do not pay interest while studying, it capitalizes onto the principal, so you begin repayment owing more than you borrowed.
Does a longer repayment term cost more?
Yes. A longer term lowers your monthly payment but increases total interest, because you carry a balance for more months. Extending a 10-year loan to 20 years can more than double the interest you pay, even though the rate is unchanged.