Student Loan Calculator
Calculate your student loan payoff timeline and total interest cost. See exactly how much extra monthly payments save you — in interest and in years off your loan.
Payoff time
10y
Minimum payment: $326/mo.
Total interest paid
$9,069
Total cost
$39,069
- Uses standard amortization: fixed monthly payment, interest accrues on the remaining balance each month.
- Extra payments are applied entirely to principal, reducing future interest and shortening the loan term.
- Does not model income-driven repayment (IDR), Public Service Loan Forgiveness (PSLF), deferment, forbearance, or origination fees.
- Formula:
P = L × r / (1 − (1 + r)^−n), whereLis the loan balance,rthe monthly rate, andnthe term in months.
How student loan interest works
Student loans accrue interest daily on the outstanding balance. Each monthly payment first covers the interest that accumulated since your last payment, and the remainder goes toward principal. Because the balance is largest in the early years, the biggest chunk of every payment goes to interest — just like a mortgage.
The total interest paid over the life of a student loan can equal or exceed the original balance. On a $60,000 loan at 6.5% over 10 years, you'll pay roughly $25,000 in interest — meaning the true cost of your degree is $85,000, not $60,000. This is why extra payments in the early years save the most money.
Why it matters to your money
Student loan debt is unique because it's often the largest debt young adults carry at the start of their careers. Making even small extra payments early can save thousands in interest and shave years off your payoff timeline. Conversely, extending your repayment term lowers your monthly payment but dramatically increases total cost.
Federal loans also offer income-driven repayment (IDR) plans that cap payments at a percentage of your discretionary income and forgive remaining balances after 10–25 years. Understanding whether IDR makes sense for your situation — and how PSLF (Public Service Loan Forgiveness) might apply — is essential for anyone with federal student debt.
Rules of thumb
- Extra $100/month saves significant interest: On a $50K loan at 6% over 10 years, $100 extra per month saves over $3,000 in interest and cuts 14 months off the payoff timeline.
- Refinance only if you won't need IDR or PSLF: Private refinancing eliminates access to income-driven repayment and Public Service Loan Forgiveness. If you work for a nonprofit or government employer, keep your federal loans.
- Pay interest while in school if you can: Unsubsidized loans accrue interest while you're in school, and that interest capitalizes (gets added to principal) when you enter repayment. Paying just the interest during school saves money long-term.
Frequently asked questions
- How much can extra payments save on student loans?
- Significant amounts. On a $50,000 loan at 6% over 10 years, paying an extra $100/month saves over $3,000 in interest and cuts roughly 14 months off the loan. The calculator shows your exact savings.
- Should I pay off student loans or invest?
- It depends on your interest rate. Federal student loans at 4–5% may be worth investing alongside. Private loans at 7–10% are usually worth aggressively paying off first. Compare your loan rate to expected investment returns.
- What is the difference between subsidized and unsubsidized federal loans?
- Subsidized loans don't accrue interest while you're in school at least half-time. Unsubsidized loans accrue interest from the day they're disbursed. If you have both, prioritize unsubsidized loans since their balance grows faster.
- What are income-driven repayment plans?
- Federal income-driven repayment plans (IBR, PAYE, SAVE) cap monthly payments at 5–20% of your discretionary income and forgive remaining balances after 10–25 years. They make sense if your debt-to-income ratio is high.