Formulas and 2026 figures checked & updated: July 2026
Loan Details
2025–26 federal undergrad rate: 6.53%
See how extra payments save interest and time
Repayment Summary
How to Use the Student Loan Calculator
- Enter your total student loan balance (for example, $35,000).
- Enter your interest rate — check your loan servicer's statement, or use the 2025–26 federal undergraduate rate of 6.53% as a starting point.
- Choose your repayment term — 10 years (120 months) is the standard federal plan, though you can model a longer or shorter term.
- Add any extra monthly payment you can afford, to see how it accelerates your payoff.
- Review your standard monthly payment, total interest, and total repayment cost.
- Compare the standard-payment scenario against the payment-with-extra scenario to see the interest saved and time saved.
- Example: a $30,000 balance at 6% over 10 years is about $333/month; adding $100/month extra pays it off about three years sooner and saves roughly $3,000 in interest.
What This Calculator Does
The Student Loan Calculator estimates your standard monthly payment, total interest, and full repayment cost for federal or private student loans, based on your balance, interest rate, and repayment term. It also models the impact of paying extra each month, so you can see exactly how much faster you'd be debt-free and how much interest you'd avoid.
The result is driven by three inputs — your loan balance, interest rate, and repayment term — plus an optional extra monthly payment that shows how much faster you could pay off the balance. For the 2025–26 academic year, federal Direct Loan rates for undergraduates sit around 6.53% fixed, with graduate Direct Unsubsidized loans near 8.08% and Direct PLUS loans near 9.08% — rates that reset annually based on the 10-year Treasury note and stay fixed for the life of each loan. Private student loans instead price off your (or a cosigner's) credit score and can range from roughly 4% to 15% APR, either fixed or variable. As a rule of thumb, if your total student debt at graduation exceeds your expected first-year salary, budgeting for income-driven repayment or an extended term is often more realistic than the standard 10-year plan.
Use this calculator to see your baseline standard-plan payment before comparing it against income-driven repayment options, to test how an extra payment each month accelerates your payoff date and cuts total interest, or to estimate what refinancing to a lower rate could save. Keep in mind that refinancing federal loans into a private loan gives up federal protections like income-driven repayment, deferment, and Public Service Loan Forgiveness (PSLF).
Formula
M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1]The same amortization formula used for any installment loan. For federal loans, P, r, and n are typically fixed by your loan terms and the standard 10-year repayment plan; income-driven plans instead cap payments as a percentage of discretionary income rather than using this formula directly. When you add an extra monthly payment, the calculator simulates the payoff month by month, applying each payment first to accrued interest and the remainder to principal until the balance reaches zero.
- POutstanding loan balance
- rMonthly interest rate (annual APR ÷ 12)
- nRepayment term in months (e.g., 120 for the standard 10-year plan)
- MFixed standard monthly payment
Examples
Example 1: $35,000 federal undergrad balance at 6.53% over 10 years
P = $35,000, the 2025-26 Direct Loan undergrad rate of 6.53%, n = 120 payments (standard plan).
Monthly payment ≈ $397.58 — total interest ≈ $12,709.60, total repaid ≈ $47,709.60.
Example 2: Same loan, with an extra $100/month
Same $35,000 balance and 6.53% rate, but paying $497.58/month instead of the standard $397.58.
Payoff time drops to roughly 7 years 7 months (about 29 months earlier) and total interest falls to around $9,500 — saving roughly $3,200.
Example 3: $80,000 grad PLUS loan at 9.08% over 15 years
P = $80,000, the 2025-26 Direct PLUS rate of 9.08%, n = 180 payments.
Monthly payment ≈ $814.46 — total interest ≈ $66,602.80, total repaid ≈ $146,602.80, illustrating why graduate borrowers often explore income-driven plans.
Key Terms Explained
- APR (Annual Percentage Rate)
- The yearly cost of borrowing shown as a percentage, including the interest rate plus certain fees. APR lets you compare loans on an equal footing and is usually a bit higher than the plain interest rate.
- Interest Rate
- The percentage a lender charges on the principal, before fees. Unlike APR, the interest rate alone doesn't include origination or other loan costs.
- Principal
- The original amount borrowed or invested, before interest. Each loan payment is split between paying down principal and paying interest.
- Amortization
- Paying off a loan through fixed payments over time. Early payments are mostly interest; later payments are mostly principal as the balance shrinks.
- Loan Term
- The length of time you have to repay a loan. A longer term lowers the monthly payment but increases the total interest paid.
- Minimum Payment
- The smallest amount a card issuer requires each month (often about 2% of the balance). Paying only the minimum maximizes interest and payoff time.
Methodology
Standard monthly payment: M = P×r(1+r)^n / [(1+r)^n−1]. Extra payment payoff simulates month-by-month balance reduction, applying each payment first to accrued interest and the remainder to principal. Interest savings = standard total interest − accelerated total interest.
Frequently Asked Questions
What is the federal student loan interest rate for 2026?+
For the 2025–2026 academic year, undergraduate Direct Subsidized and Unsubsidized loans carry a 6.53% fixed rate. Graduate Unsubsidized loans are 8.08%, and Direct PLUS loans are 9.08%. Rates are set annually by Congress based on 10-year Treasury yields.
What is income-driven repayment (IDR)?+
IDR plans cap monthly payments at 5–20% of your discretionary income and forgive remaining balances after 10–25 years. The SAVE plan (newest) caps undergraduate loan payments at 5% of discretionary income. Use this calculator for standard repayment; IDR amounts depend on your income.
Should I pay off student loans early?+
If your loan rate is below ~6–7%, investing extra cash in a diversified portfolio may produce better long-term returns. Above that rate, extra loan payments are a guaranteed risk-free return equal to the interest rate. Pay off private loans with high rates first.
Should I refinance federal student loans into a private loan?+
Refinancing federal loans into a private loan can lower your rate and payment if your credit has improved and you're confident you won't need federal protections. But it's generally not worth it if you might need income-driven repayment, deferment, forbearance, or Public Service Loan Forgiveness (PSLF) in the future, since those benefits are permanently forfeited once you refinance into a private loan. Compare your potential savings against the value of the protections you'd give up before deciding.
What happens if I can't afford my student loan payments?+
If you have federal loans, you can typically switch to an income-driven repayment plan, request a deferment, or apply for forbearance to temporarily pause or reduce payments without defaulting. Private loan borrowers should contact their servicer directly, since hardship options vary by lender and may include temporary forbearance or a modified repayment plan. Acting before you miss a payment gives you far more options than waiting until you're already delinquent.
Is there a penalty for paying off a student loan early?+
No — federal student loans and the large majority of private student loans have no prepayment penalty, so you can pay extra or pay off the balance early without a fee. Any extra payment you make is applied to the principal, which reduces the interest that accrues going forward. Always confirm with your loan servicer that extra payments are being applied to principal and not simply advancing your next due date.
Can I save my results?+
Yes. Use “Save results” to store a snapshot. Without an account it remains in this browser. If you log in, saved scenarios sync securely to your SmartRates account so they are available on your other devices.
How do I share my calculation?+
Click “Share” in the toolbar to copy a link (or open your device’s share sheet). The link encodes your exact inputs, so whoever opens it sees the calculator pre-filled with the same numbers and the same result.
Can I email my calculator results?+
Yes. Click “Email results” to open your default email application with the current inputs, results, and calculator link already included. Review the message and choose the recipient before sending.
Can I export or print my results as a PDF?+
Yes. Click “Export PDF” to open a clean, printable summary of your inputs and results that you can save as a PDF or print. It includes a timestamp and a link back to the calculator.
How accurate are the calculator results?+
The arithmetic follows the formula and assumptions documented on this page. The result is still an estimate because actual rates, fees, taxes, timing conventions, eligibility rules, and provider calculations can differ. Use figures from your official quote, statement, contract, or tax form before making a financial decision.
Which inputs have the biggest effect on the result?+
Rate, time, starting balance, recurring payments or contributions, and fees usually have the largest effects. Change one input at a time to create a conservative, expected, and optimistic scenario instead of relying on a single forecast.
Are taxes, fees, and inflation included?+
Only when they appear as an input or are explicitly described in the methodology. Do not assume an omitted cost is zero. Review the formula and methodology sections to see exactly what is included before comparing the result with an outside quote.
Can this calculator predict future rates or returns?+
No. A calculator projects the assumptions entered; it cannot predict market returns, inflation, variable interest rates, tax-law changes, or provider decisions. Rerun the calculation with several assumptions to understand the range of possible outcomes.
Why might my lender, bank, broker, or tax software show a different result?+
Professional systems may use daily timing, transaction dates, compounding conventions, rounding rules, account-specific fees, credits, eligibility details, or regulations that a general-purpose calculator cannot know. A small difference can be rounding; a large difference usually means an assumption or included cost is different.
Disclaimer: Calculations are for informational purposes only and do not constitute professional financial advice. Please consult with a certified professional before making financial decisions.