Student Loan Calculator

Student Loan Calculator

Student loan debt is the second-largest category of consumer debt in the U.S., with the average bachelor’s degree graduate carrying $29,400 in federal loans as of 2024. This calculator computes your monthly payment, total interest, and full repayment cost for any loan balance, interest rate, and term. Whether you are comparing repayment plan options, modeling the impact of extra payments, or deciding whether to refinance, the numbers here show you exactly what your choice costs.

How Student Loan Payments Are Calculated

Monthly payments follow the standard amortization formula:

M = P x [r(1+r)^n] / [(1+r)^n — 1]

• P = loan balance
• r = monthly interest rate (annual rate divided by 12)
• n = total number of monthly payments
• Total Interest = (M x n) — P

For a $35,000 loan at 5.5% APR over 10 years: r = 0.055/12 = 0.004583. M = $380/month. Total repaid = $380 x 120 = $45,600. Total interest = $10,600. Extending to 25 years drops the payment to $215/month but pushes total interest to $29,400 — nearly as much as the original principal.

Worked Examples

Scenario 1 — Public university undergrad, standard repayment

Balance: $31,000 in federal Direct Loans at 5.5% (2024-25 undergrad rate). Standard 10-year repayment. Monthly payment: $336. Total interest: $9,337. Total cost: $40,337. If they add $100/month extra: payoff in 7.5 years, interest drops to $6,820, saving $2,517.

Scenario 2 — Graduate student, extended repayment

Balance: $75,000 in Grad PLUS loans at 8.05% (2024-25 rate). Borrower opts for 20-year extended repayment to keep payments affordable on a $52,000 starting salary. Monthly payment: $630. Total interest: $76,200. Total cost: $151,200. On the 10-year standard plan: $914/month, $34,700 total interest. The 20-year plan saves $284/month but costs $41,500 more in interest.

Scenario 3 — Private loan refinance scenario

Balance: $42,000 private loan originally at 9.8% APR, 15-year term. Monthly payment: $443. Total remaining interest: $37,700. Borrower refinances to 5.9% with 10 years remaining. New payment: $465 (+$22/month). New total interest: $13,800. Net savings from refinancing: $23,900 over the life of the loan.

Student Loan Payment Reference Table

When to Use This Calculator

• You are starting repayment and want to compare the 10-year standard plan against extended or income-driven options
• You are considering refinancing and want to see how a lower rate changes your total interest cost
• You want to find out how much extra monthly payment it takes to pay off your loans 2-5 years early
• You are a parent or student evaluating how much borrowing for a specific school is actually affordable given post-graduation income
• You want to understand whether Public Service Loan Forgiveness or aggressive repayment produces a better financial outcome for your situation

Common Mistakes to Avoid

1. Choosing extended repayment to lower the payment without calculating the interest cost. Extending federal loans from 10 to 25 years on a $50,000 balance at 6.8% adds roughly $40,000 in interest. The lower payment feels like relief but the total cost is far higher.
2. Refinancing federal loans without understanding what you give up. Refinancing federal loans into a private loan eliminates access to income-driven repayment, Public Service Loan Forgiveness, and federal forbearance. If there is any chance you will need those protections, the rate savings need to be substantial to justify the trade-off.
3. Ignoring interest that accrues during grace periods and deferment. Unsubsidized federal loans accrue interest from the day they are disbursed, including during the 6-month post-graduation grace period. On a $30,000 balance at 6.5%, that is roughly $975 in accrued interest before your first payment. Paying it before it capitalizes saves money.
4. Treating income-driven repayment as a long-term strategy without modeling forgiveness taxes. IDR forgiveness after 20-25 years is currently taxable income in most cases. A $60,000 forgiven balance could generate a tax bill of $14,000-$20,000 in the forgiveness year.

Current Context for 2026

Federal student loan interest rates for 2025-26 are set annually in June based on the 10-year Treasury yield plus a fixed add-on. Undergraduate Direct Loan rates are approximately 6.53%, graduate unsubsidized rates are around 8.08%, and Grad PLUS rates are near 9.08% — all meaningfully higher than rates from 2020-2022. The SAVE plan, which was the newest IDR option, faced legal challenges in 2024-25, leaving many borrowers in limbo. The surviving IDR plans — IBR, PAYE, and ICR — remain available. Total outstanding federal student loan debt reached approximately $1.75 trillion in 2025. For borrowers with strong credit and stable income, private refinancing rates from competitive lenders start around 5.0-5.5% in early 2026, which can produce meaningful savings for those with pre-2022 federal loan rates above 6%.

Tips

1. Run the calculator for both the 10-year standard plan and any extended or IDR option you are considering — the interest difference is often $20,000-$50,000 and needs to be explicit before you decide
2. Even $75-$100 extra per month makes a significant difference on a 10-year loan — on $35,000 at 5.5%, it cuts roughly 2 years off repayment and saves $2,300 in interest
3. If you are pursuing Public Service Loan Forgiveness, stay on an IDR plan and verify employment eligibility annually through the PSLF Help Tool — mistakes can disqualify payments retroactively
4. For private loan refinancing, compare at least 3-4 lenders since rate differences of 1-2% on $50,000 represent $5,000-$10,000 in savings over a 10-year term
5. Pay off interest that capitalizes during grace periods or deferment before it is added to your principal, which would increase the base on which future interest is calculated
6. If your federal loan balance is under $30,000 and you have a stable income, aggressive standard repayment often beats IDR plans in total cost even when IDR seems appealing

Related Calculations

• Personal Loan Calculator: See how private refinancing compares to your current federal loan cost
• Loan Comparison Calculator: Compare two loan offers side by side with different rates, amounts, and terms
• Debt Payoff Calculator: Find out exactly how extra monthly payments reduce your payoff timeline
• Debt-to-Income Ratio Calculator: Check whether your student loan payments are sustainable relative to your income
• Interest Rate Calculator: Back-calculate the implied rate from a refinance lender’s quoted monthly payment