Last updated March 2026
Student Loan Calculator
Calculate your monthly student loan payment, total interest, and see how extra payments can save you money.
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Understanding Student Loan Interest
Student loan interest is the cost of borrowing money for education. When you take out a student loan, the lender charges interest as a percentage of the outstanding balance, and this interest accrues over the life of the loan. Understanding how interest works is critical to managing your student debt effectively.
Most student loans use simple daily interest. The daily interest amount is calculated by multiplying the outstanding principal by the interest rate and dividing by 365. For example, a $30,000 loan at 5.5% accrues approximately $4.52 per day in interest. Over 10 years, this adds up to thousands of dollars on top of the original amount borrowed.
M = P[r(1+r)n] / [(1+r)n - 1] In this formula, M is the monthly payment, P is the principal (loan amount), r is the monthly interest rate (annual rate divided by 12), and n is the total number of payments (years multiplied by 12).
Student Loan Repayment Strategies
Choosing the right repayment strategy can save you thousands of dollars and years of payments. Here are the most effective approaches:
The Avalanche Method
Pay the minimum on all loans, then direct extra payments toward the loan with the highest interest rate. This approach minimizes total interest paid and is mathematically optimal. Once the highest-rate loan is paid off, roll that payment into the next highest-rate loan.
The Snowball Method
Pay the minimum on all loans, then direct extra payments toward the loan with the smallest balance. While this costs slightly more in total interest, it provides psychological wins by eliminating individual loans faster, which helps many borrowers stay motivated.
Extra Payments
Even small extra payments make a meaningful difference. Adding just $100 per month to a $35,000 loan at 5.5% over 10 years saves over $2,500 in interest and pays the loan off almost 2 years early. Use the calculator above to see exactly how much extra payments would save in your situation.
Federal vs. Private Student Loans
Federal student loans are funded by the U.S. government and offer several advantages. They have fixed interest rates set by Congress, access to income-driven repayment (IDR) plans, deferment and forbearance options, and eligibility for Public Service Loan Forgiveness (PSLF). Federal Direct Subsidized Loans do not accrue interest while you are enrolled at least half-time.
Private student loans are offered by banks, credit unions, and online lenders. They may have fixed or variable interest rates, and rates depend on your credit score and income. Private loans typically lack the flexible repayment options and forgiveness programs available with federal loans. However, borrowers with excellent credit may qualify for lower rates than federal loans offer.
As a general rule, exhaust federal loan options before turning to private loans. If you do have private loans, refinancing when rates are favorable can lower your monthly payment and total interest cost.
Income-Driven Repayment Options
Federal borrowers who cannot afford standard payments may qualify for income-driven repayment (IDR) plans that cap monthly payments at a percentage of discretionary income:
- SAVE Plan: Payments are 5-10% of discretionary income, with remaining balances forgiven after 20-25 years.
- PAYE: Payments capped at 10% of discretionary income, with forgiveness after 20 years.
- IBR: Payments are 10-15% of discretionary income, forgiven after 20-25 years depending on when you borrowed.
- ICR: Payments are 20% of discretionary income or the amount on a 12-year fixed plan, whichever is less, forgiven after 25 years.
While IDR plans lower monthly payments, they often increase total interest paid due to the extended repayment period. Any forgiven balance may also be considered taxable income, depending on the specific program and current tax law.
Student Loan Forgiveness Programs
Several federal programs may forgive part or all of your student loan balance:
Public Service Loan Forgiveness (PSLF)
If you work full-time for a qualifying government or nonprofit employer and make 120 qualifying payments (10 years) under an income-driven repayment plan, your remaining federal loan balance is forgiven tax-free. This program can be extremely valuable for borrowers with large balances who work in public service careers such as teaching, nursing, law enforcement, or government administration.
Teacher Loan Forgiveness
Teachers who work for five consecutive years in a low-income school may qualify for up to $17,500 in federal loan forgiveness. STEM and special education teachers qualify for the higher amount, while other subject teachers may receive up to $5,000.
Refinancing Student Loans
Refinancing involves taking out a new private loan to pay off your existing student loans, ideally at a lower interest rate. This can reduce your monthly payment and total interest cost. However, refinancing federal loans into a private loan means giving up federal protections like income-driven repayment, deferment, and forgiveness eligibility.
Refinancing makes the most sense when you have strong credit (720+), stable income, and do not need federal repayment protections. Compare offers from multiple lenders, and pay close attention to whether the rate is fixed or variable. A variable rate that starts low may increase significantly over the life of the loan.
Frequently Asked Questions
How is a student loan monthly payment calculated?
Student loan monthly payments are calculated using the standard amortization formula: M = P[r(1+r)^n]/[(1+r)^n-1], where P is the loan principal, r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments. For example, a $30,000 loan at 5.5% over 10 years would have a monthly payment of approximately $325.
Should I make extra payments on my student loans?
Making extra payments can save you significant money on interest and help you become debt-free sooner. Even an extra $50 or $100 per month can shave years off your repayment timeline. Be sure to specify that extra payments should be applied to the principal balance, and prioritize higher-interest loans first if you have multiple loans.
What is the difference between federal and private student loans?
Federal student loans are issued by the government and offer fixed interest rates, income-driven repayment plans, deferment and forbearance options, and potential loan forgiveness programs. Private student loans are issued by banks and lenders, often have variable interest rates, and typically offer fewer borrower protections. Federal loans are generally recommended before considering private options.
Related Calculators
- Loan Amortization Calculator - See a detailed amortization schedule for any loan.
- Debt-to-Income Calculator - Check if your debt levels are healthy.
- Compound Interest Calculator - Understand how interest grows over time.