π Student Loan Calculator
Your monthly payment and the true total cost.
Monthly payment
Estimates for planning only, not financial advice.
Borrow $30,000 at 6 percent for 10 years and the payment is $333.06 a month. You will pay $9,967 in interest, making the real cost of that degree $39,967. Add $100 extra a month and you finish years early while saving thousands in interest.
How to Use This Calculator
Enter your total loan balance, interest rate, and repayment term, then optionally add an extra monthly payment to see the payoff acceleration. Federal and private loans both use standard amortization, so the same math applies.
Enter the full balance. If you have multiple loans at different rates, run the highest-rate one here first.
Enter the APR and term. Federal loans offer 10-year standard; private loans vary from 5 to 20 years.
Add an extra payment to see interest saved and months cut. Even $50 matters more than it looks.
The Formula
Standard amortization: each payment covers that month's interest first, and the rest attacks principal. Early payments are mostly interest; late payments are mostly principal. That front-loading is why extra payments early in the loan save disproportionately: every extra dollar then avoids years of interest accrual.
Worked Example
$30,000 at 6 percent APR for 10 years. Monthly rate: 0.005. Payments: 120. Payment: 30,000 x 0.005 x 1.005^120 / (1.005^120 - 1) = $333.06. Total paid: 333.06 x 120 = $39,967. Total interest: $9,967, a third of the principal again. Now add $100 a month ($433.06 total): the loan clears in about 87 months instead of 120, total interest falls to roughly $6,900, saving about $3,000 and nearly 3 years. That $100 a month bought a 30 percent interest cut.
Federal vs Private: Different Games
| Feature | Federal loans | Private loans |
|---|---|---|
| Rate | Fixed, set by Congress yearly | Fixed or variable, credit-based |
| Repayment plans | Standard, graduated, extended, income-driven | Whatever the lender offers |
| Forgiveness | PSLF, IDR forgiveness exist | Essentially none |
| Forbearance | Generous, standardized | Lender's discretion |
| Refinancing | Possible but forfeits protections | Core product |
The golden rule: never refinance federal loans into private ones unless you are certain you will never need income-driven repayment or forgiveness. The rate savings, often 1 to 2 percent, rarely compensate for the lost safety net. Compare repayment strategies with our federal repayment plan comparison and payoff tactics in the student loan payoff planner.
Should You Pay Extra or Invest?
Compare your loan rate against expected investment returns, adjusted for risk. At 6 to 8 percent loan rates, extra payments are a guaranteed 6 to 8 percent return, which beats most safe investments and rivals expected stock returns without the volatility. Below 5 percent, investing the extra often wins mathematically, though the psychological value of being debt-free is real and unpriced. One exception: always capture a 401(k) employer match first. A 100 percent immediate return on matched contributions beats any loan prepayment.
The Interest Capitalization Trap
Unsubsidized federal loans accrue interest while you are in school, and unpaid interest capitalizes, gets added to principal, when repayment begins. A $30,000 loan at 6 percent accrues $1,800 a year in school; four years of non-payment adds roughly $7,200 to the balance before you make payment one. Paying interest while enrolled, even partially, prevents the balance from growing behind your back. It is the cheapest money you will ever put toward the loan.
Federal vs Private: the Protections Gap
The interest rate is the least important difference between federal and private student loans. Federal loans carry income-driven repayment, Public Service Loan Forgiveness eligibility, generous deferment and forbearance, and discharge on death or permanent disability. Private loans carry none of these by law; each lender's hardship options are voluntary and thin. A borrower who loses their job with federal loans can drop to a $0 IDR payment; the same borrower with private loans is negotiating forbearance month by month.
That gap should order your decisions. Exhaust federal loans before touching private ones, even when a private lender advertises a lower rate: the rate difference is small, the protection difference is enormous. When refinancing federal loans into private ones for a lower rate, you are selling an insurance policy; price it as one. The only borrowers who should refinance are those with high incomes, secure jobs, and no need for forgiveness programs, and even they should think twice.
Borrow Less, Then Borrow Smart
The cheapest student loan is the one you never take: every $1,000 not borrowed at 6 percent saves about $1,330 in payments over ten years. When borrowing is unavoidable, max out federal loans before touching private ones, because no private rate discount compensates for losing IDR, PSLF, and forbearance rights. Then automate payments, recertify IDR income annually, and attack the highest-rate loan first while paying minimums elsewhere. The system punishes the disorganized far more than it rewards the clever.
Estimates for planning only, not financial advice.
Frequently Asked Questions
How is a student loan monthly payment calculated?
With standard amortization: payment = P x r(1+r)^n / ((1+r)^n - 1), where P is balance, r monthly rate, n number of payments. A $30,000 loan at 6 percent for 10 years gives $333.06 a month. Each payment covers interest first, then principal.
How much interest will I pay on my student loan?
Multiply payment by number of payments and subtract the principal. On $30,000 at 6 percent for 10 years: $333.06 x 120 - $30,000 = $9,967 in interest. Longer terms and higher rates raise this fast: the same loan over 20 years costs about $21,000 in interest.
Does paying extra on student loans help?
Enormously. An extra $100 a month on the $30,000 example cuts payoff from 120 to about 87 months and saves roughly $3,000 in interest. Extra payments attack principal directly, and early in the loan each extra dollar avoids years of interest.
Should I pay off student loans or invest?
Above 6 percent loan rates, prepaying is a guaranteed return that usually wins. Below 5 percent, investing often wins mathematically. Always take a 401(k) employer match first regardless. Factor in forgiveness eligibility: prepaying a loan headed for PSLF forgiveness wastes money.
What is the standard student loan repayment term?
10 years (120 payments) for federal loans, the default if you choose nothing. Extended plans run 25 years with lower payments but much more interest. Private loans typically offer 5, 10, 15, or 20-year terms. The 10-year standard is also the benchmark forgiveness plans compare against: PSLF forgives after 120 payments, exactly the standard term, so only IDR enrollees have balances left to forgive.
Can I refinance my student loans?
Yes, through private lenders, often at lower rates if your credit and income are strong. But refinancing federal loans into private ones permanently forfeits income-driven repayment, forbearance rights, and forgiveness programs. Only refinance federal loans if you are sure you will never need those protections.
What happens if I miss a student loan payment?
Federal loans become delinquent immediately and are reported to credit bureaus after 90 days; after 270 days they default, triggering wage garnishment and tax refund seizure. Contact your servicer before missing: income-driven plans, deferment, and forbearance exist precisely for this.
Is student loan interest tax deductible?
Up to $2,500 a year in student loan interest is deductible above the line, subject to income phaseouts ($75,000-$90,000 single in recent years). You do not need to itemize. The deduction covers interest actually paid, which is why extra payments do not increase it much.
What is interest capitalization?
When unpaid interest is added to your principal balance, so you start paying interest on interest. It happens on unsubsidized federal loans when grace, deferment, or forbearance ends. Paying interest while in school prevents the balance from growing before repayment starts.
How do I find my total student loan balance?
Log into studentaid.gov for all federal loans in one dashboard. Private loans appear on your credit report and lender statements. Add them together for the true total, then run the highest-rate loan through this calculator first. While you are there, confirm each loan's type (Direct vs FFEL) and servicer, since both determine which forgiveness and repayment programs you can actually use.