Student Loan Interest Calculator
Calculate your monthly student loan payment, total interest paid, and how much you save by making extra monthly payments.
These calculators are for informational purposes only and do not constitute financial, legal, or tax advice.
Results are educational estimates only. Actual tuition, financial aid, loan terms and repayment options vary by institution and government regulations. This tool does not represent official FAFSA, Department of Education, or loan servicer calculations.
See exactly how much interest your student loan will cost — and how small changes to your payment can save you thousands.
What Is a Student Loan Interest Calculator?
A student loan interest calculator estimates how much interest you’ll pay over the life of your loan, based on your balance, interest rate, and repayment term. It shows your monthly payment, total interest paid, and total repayment amount, so you know the real cost of borrowing before — or during — repayment.
Most borrowers focus on the amount they’re borrowing. Far fewer think carefully about interest — but interest is often what turns a $40,000 loan into a $53,000+ repayment obligation over time. Understanding how interest works before you borrow, or before you pick a repayment plan, can save you real money.
Interest accrues on your loan balance every single day it’s outstanding, whether you’re in school, in a grace period, or actively repaying. The longer your balance sits, and the higher your rate, the more you’ll ultimately pay above what you originally borrowed. A Student Loan Interest Calculator takes your numbers and shows you that true cost clearly, so you can make an informed borrowing and repayment decision instead of guessing.
What Is Student Loan Interest?
Student loan interest is the cost of borrowing money, charged as a percentage of your outstanding balance. Here’s how the key terms fit together:
Principal — the original amount you borrowed, before any interest is added.
Interest rate — the annual percentage charged on your outstanding balance.
APR (Annual Percentage Rate) — a broader cost measure that can include certain fees along with the interest rate, giving a fuller picture of borrowing cost.
Fixed interest rates — stay the same for the life of the loan. All current federal student loans use fixed rates.
Variable interest rates — can rise or fall over time based on market conditions. Some private loans offer variable rates, usually starting lower but carrying more long-term uncertainty.
Accrued interest — interest that has built up on your loan but hasn’t yet been added to your principal balance.
Capitalized interest — accrued interest that gets added to your principal balance (often when you leave school or exit a grace period, deferment, or forbearance), meaning future interest is then charged on that larger amount.
Example: if you have a $10,000 loan and $600 in unpaid interest accrues while you’re in school, and that interest capitalizes, your new principal becomes $10,600 — and future interest is calculated on $10,600, not the original $10,000.
How Does a Student Loan Interest Calculator Work?
At its simplest, interest can be understood with the simple interest formula:
• Loan amount — the principal balance the interest is calculated on.
• Interest rate — the annual rate applied to that balance.
• Loan term — how many years you have to repay.
• Repayment period — the specific window (monthly, in most cases) interest and payments are calculated over.
Real student loans use this concept but apply it monthly, on a shrinking balance, in what’s called an amortized loan — meaning each payment covers that month’s interest first, with the remainder reducing your principal.
Student Loan Interest Calculator Formula
Monthly Interest
Daily Interest (Simple Daily Accrual)
Amortized Monthly Payment
Where P is your loan amount, r is your monthly interest rate (annual rate ÷ 12), and n is your total number of monthly payments.
Worked Example
| Input | Value |
|---|---|
| Loan amount | $40,000 |
| Interest rate | 6% |
| Repayment term | 10 years |
| Monthly payment | $444.14 |
| Total interest paid | $13,296.80 |
| Total repayment amount | $53,296.80 |
In other words: on a $40,000 loan at 6% over 10 years, you’ll ultimately repay about $13,300 more than you borrowed — roughly a third extra, just in interest.
Student Loan Interest Calculator Inputs
| Input | Description |
|---|---|
| Loan amount | Total amount borrowed |
| Interest rate | Annual interest percentage |
| Loan term | Repayment duration |
| Repayment type | Standard, graduated, or income-driven |
| Additional monthly payment | Optional extra payment toward principal |
| Grace period | Months before repayment begins |
Your repayment type changes how payments are structured: Standard spreads payments evenly, Graduated starts lower and rises every two years, and Income-driven ties payments to your earnings rather than your balance. Adding an additional monthly payment goes straight to principal, cutting both your payoff time and total interest. Your grace period — typically six months after leaving school for federal loans — is time before required payments start, though interest may still accrue during it depending on your loan type.
Federal vs. Private Student Loans
| Feature | Federal Loans | Private Loans |
|---|---|---|
| Interest rates | Fixed, set annually by Congress | Fixed or variable, based on lender and credit |
| Repayment plans | Standard, graduated, income-driven, and more | Set by lender, usually less flexible |
| Forgiveness options | PSLF, Teacher Loan Forgiveness, IDR forgiveness | None |
| Income-driven plans | Yes (IBR, RAP) | Not available |
| Deferment | Available for eligible circumstances | Rare, lender-dependent |
| Forbearance | Available, generally easier to obtain | Sometimes offered, terms vary widely |
The biggest difference is flexibility. Federal loans come with built-in borrower protections — income-driven plans, deferment, forbearance, and forgiveness options — that private loans simply don’t offer. Private loans can sometimes offer a lower rate to borrowers with excellent credit, but they come with far fewer safety nets if your financial situation changes.
How Interest Affects Student Loan Repayment
Higher interest rates increase costs because more of every payment goes toward interest instead of shrinking your balance. On the same $40,000 loan, moving from 6% to 8% over 10 years raises your monthly payment from about $444 to about $485, and total interest from about $13,300 to roughly $18,200 — nearly $5,000 more, from a 2-point rate difference alone.
Longer repayment terms increase total interest even if your rate stays the same, because your balance sits outstanding for more months, accruing interest the whole time. Stretching that same $40,000 loan at 6% from 10 years to 20 years cuts your monthly payment to about $287, but nearly doubles your total interest to roughly $28,800.
Delaying payments — through deferment, forbearance, or simply not paying during school — lets interest accrue uninterrupted. Even small payments during these periods can meaningfully reduce what eventually capitalizes onto your balance.
Capitalized interest compounds the problem, since future interest then applies to a larger principal — effectively making your loan bigger before you’ve even started active repayment.
Student Loan Interest by Loan Type
| Loan Type | 2026-27 Rate |
|---|---|
| Direct Subsidized Loans (undergraduate) | 6.52% |
| Direct Unsubsidized Loans (undergraduate) | 6.52% |
| Direct Unsubsidized Loans (graduate/professional) | 8.07% |
| Grad PLUS / Parent PLUS Loans | 9.07% |
| Private Student Loans | Roughly 4%–15%, credit-dependent (general range) |
| Refinanced Student Loans | Varies by lender and credit profile |
Rates shown are for federal Direct Loans first disbursed between July 1, 2026 and June 30, 2027 — the current window as of this writing. Federal rates reset annually every July 1; always confirm the current rate before borrowing. Private and refinance rates shown are general ranges only and vary continuously by lender, credit score, and market conditions.
How to Reduce Student Loan Interest
✓ Make payments during school — even small payments prevent accrued interest from capitalizing later.
✓ Pay more than the minimum — extra payments go straight to principal, cutting future interest.
✓ Refinance at a lower rate — if you qualify, refinancing can reduce your rate (note: refinancing federal loans into a private loan forfeits federal protections and forgiveness eligibility).
✓ Use automatic payments — many servicers offer a small rate discount (often 0.25%) for autopay enrollment.
✓ Choose shorter repayment terms — higher monthly payments, but significantly less total interest.
✓ Avoid unnecessary deferment — pausing payments when you don’t need to just lets more interest accrue.
✓ Make biweekly payments — splitting your monthly payment in two, paid every two weeks, results in one extra full payment per year.
Common Student Loan Interest Scenarios
Scenario 1: Undergraduate Student
| Detail | Value |
|---|---|
| Loan amount | $25,000 |
| Interest rate | 5% |
| Term | 10 years |
| Monthly payment | $265.06 |
| Total interest | $6,807.20 |
Scenario 2: Graduate Student
| Detail | Value |
|---|---|
| Loan amount | $75,000 |
| Interest rate | 7% |
| Term | 15 years |
| Monthly payment | $674.15 |
| Total interest | $46,347 |
Scenario 3: Extra Monthly Payments
Take Scenario 1’s $25,000 loan at 5% over 10 years ($265.06/month, $6,807 in total interest). Adding just $50 extra per month ($315.06/month total):
| Result | Value |
|---|---|
| New payoff time | ~8 years, 1 month (vs. 10 years) |
| Interest saved | ~$1,390 |
Just $50 a month — often less than one streaming bundle plus a food delivery order — cuts nearly two years off this loan and saves close to $1,400 in interest. Small, consistent extra payments are one of the most reliable ways to reduce your true borrowing cost.
See your own interest breakdown
Enter your loan amount, rate, and term to see your monthly payment and total interest.
Frequently Asked Questions
How is student loan interest calculated?
Interest is calculated by applying your annual interest rate to your outstanding balance, typically divided into a daily or monthly rate, and charged for each day or month the balance remains unpaid.
How much interest will I pay on my student loan?
It depends on your balance, rate, and term. As a benchmark, a $40,000 loan at 6% over 10 years costs about $13,300 in total interest — roughly a third more than the amount borrowed.
Do federal student loans accrue interest while in school?
Direct Subsidized Loans don’t accrue interest while you’re in school at least half-time. Direct Unsubsidized and PLUS Loans do accrue interest from disbursement, even while you’re enrolled.
What is capitalized interest?
Capitalized interest is unpaid, accrued interest that gets added to your loan’s principal balance, usually when you leave school or exit a grace period, deferment, or forbearance — meaning future interest is then charged on the larger amount.
How often is student loan interest calculated?
Most federal student loans accrue interest daily, using a simple daily interest formula based on your current balance, even though you’re typically billed monthly.
Can I reduce my student loan interest?
Yes — paying more than the minimum, making payments during school, choosing a shorter term, or refinancing at a lower rate can all reduce the total interest you pay.
Is student loan interest tax deductible?
Many borrowers can deduct up to $2,500 in student loan interest paid per year, subject to income limits — check current IRS rules or a tax professional to confirm your eligibility.
Do private student loans have higher interest rates?
Not always — borrowers with excellent credit can sometimes get lower private rates than federal PLUS loans, but private loans lack federal protections like income-driven repayment and forgiveness.
How does refinancing affect interest?
Refinancing can lower your rate and total interest if you qualify for better terms, but refinancing federal loans into a private loan means giving up federal benefits like income-driven repayment and forgiveness eligibility.
Can I pay off my student loans early?
Yes, federal and most private student loans have no prepayment penalty, so paying extra or paying off your balance early only saves you money in interest.
What’s the difference between subsidized and unsubsidized loans?
Subsidized loans don’t accrue interest while you’re in school; unsubsidized loans start accruing interest immediately from disbursement, regardless of enrollment status.
Does a longer loan term always mean more total interest?
Generally yes — a longer term lowers your monthly payment but keeps your balance outstanding longer, so more total interest accrues over the life of the loan.
What is a grace period?
A grace period is a set window — typically six months for federal loans — after you leave school before required payments begin, though interest may still accrue during it on unsubsidized loans.
How do biweekly payments reduce interest?
Paying half your monthly payment every two weeks results in 26 half-payments per year — equivalent to 13 full monthly payments instead of 12 — which shortens your loan term and cuts total interest.
Do extra payments always reduce interest the same amount?
No — extra payments made earlier in the loan save more interest than the same extra payment made later, since interest compounds on whatever balance remains outstanding.
Key Takeaways
• Interest can add 30% or more to your total repayment cost, even at moderate rates.
• A calculator turns your loan amount, rate, and term into a clear monthly payment and true total cost.
• Repayment strategy matters — term length, extra payments, and timing all meaningfully change your total interest.
• Small changes, like an extra $50 a month, can save well over a thousand dollars and cut years off your repayment.
Related Calculators
This calculator and content are for general educational purposes only and do not constitute financial or tax advice. Interest rates change annually for federal loans and continuously for private loans — always verify your loan’s actual rate and terms with your servicer. Projections are estimates and are not guarantees of your actual repayment cost.