Student Loan Payment Calculator
Find your fixed monthly payment and total interest cost for any student loan. Use it when comparing repayment terms or evaluating refinancing options.
About this calculator
Student loan monthly payments are calculated using the standard amortization formula for a fixed-rate installment loan. The formula is: M = L × (r × (1 + r)^n) / ((1 + r)^n − 1), where L is the loan principal, r is the monthly interest rate (annual rate ÷ 12 ÷ 100), and n is the total number of monthly payments (years × 12). This ensures each payment covers accruing interest while steadily reducing principal over the loan term. Total interest paid equals (M × n) − L. A grace period delays repayment but interest may continue to accrue during that time, increasing the effective balance when payments begin. Longer repayment terms lower your monthly payment but significantly increase total interest paid over the life of the loan.
How to use
Assume a $30,000 loan at 5.5% annual interest over 10 years with no grace period. First, r = 5.5 / 100 / 12 = 0.004583. Then n = 10 × 12 = 120 payments. Numerator: 30,000 × (0.004583 × (1.004583)^120) = 30,000 × (0.004583 × 1.7331) = 30,000 × 0.007944 = 238.32. Denominator: (1.004583)^120 − 1 = 0.7331. Monthly payment M = 238.32 / 0.7331 ≈ $325.12. Total repaid = $325.12 × 120 = $39,014. Total interest = $39,014 − $30,000 = $9,014.
Frequently asked questions
How does the repayment term length affect my total student loan interest?
Extending your repayment term lowers your monthly payment but dramatically increases the total interest you pay. For example, a $30,000 loan at 5.5% costs about $9,014 in interest over 10 years but roughly $26,000 over 25 years. The extra monthly cash flow from a longer term can be valuable, but you should weigh it against the significantly higher lifetime cost. Refinancing to a shorter term when your income allows is a common strategy to reduce total interest.
What happens to my student loan balance during a grace period?
Most federal student loans offer a 6-month grace period after graduation before payments begin, but unsubsidized loans continue to accrue interest during this time. That accrued interest capitalizes — meaning it gets added to your principal balance — at the end of the grace period, making your effective starting balance higher than the original loan amount. Subsidized loans do not accrue interest during the grace period. You can make voluntary payments during the grace period to prevent capitalization.
How do I use this calculator to compare refinancing my student loans?
Enter your current remaining balance as the loan amount, then try different interest rates and repayment terms to see the resulting monthly payment and total interest. For instance, refinancing a $25,000 balance from 6.8% to 4.5% over the same remaining term can save thousands in total interest. Be cautious about refinancing federal loans into private loans, as you would lose access to income-driven repayment plans and federal forgiveness programs.