Student Loan Calculator - Payment & Payoff
Calculate monthly student loan payments, total interest, and payoff timeline. Supports federal and private loans with income-driven repayment comparisons.
Formula
M = P[r(1+r)^n]/[(1+r)^n-1]
Standard amortization formula. Income-driven plans use percentage of discretionary income instead.
Worked Examples
Example 1: Standard 10-Year Repayment
Problem:Graduate with $35,000 in federal loans at 5.5% average. Calculate standard repayment.
Solution:Standard plan: 120 monthly payments\n\nPayment calculation:\nP = $35,000, r = 5.5%/12 = 0.458%, n = 120\nPMT = $35,000 × [0.00458(1.00458)^120] / [(1.00458)^120 - 1]\nPMT = $380.56/month\n\nTotal paid: $380.56 × 120 = $45,667\nTotal interest: $45,667 - $35,000 = $10,667\n\nAfter 5 years (60 payments):\nBalance remaining: ~$19,200\nPrincipal paid: ~$15,800\nInterest paid: ~$7,033
Result:$381/month | $10,667 interest over 10 years
Example 2: Income-Driven vs Standard Comparison
Problem:Same $35,000 at 5.5%. Starting salary $45,000, 3% annual raises. Compare SAVE plan (5% discretionary) vs standard.
Solution:Standard plan:\nPayment: $381/month fixed\nPayoff: 10 years\nTotal interest: $10,667\n\nSAVE plan (5% of discretionary income):\nYear 1 discretionary: $45,000 - ~$24,000 FPL = $21,000\nYear 1 payment: $21,000 × 5% ÷ 12 = $87.50/month\n...\nYear 10 payment: ~$155/month (salary growth)\nBalance after 10 years: ~$31,000 (interest accrued)\nForgiven after 20-25 years: remaining balance\n\nSAVE is better if: pursuing forgiveness, income stays low, or need cash flow flexibility.
Result:IDR: lower payment but longer payoff
Example 3: Extra Payments Impact
Problem:$50,000 at 6% for 10 years. Compare standard vs adding $200/month extra.
Solution:Standard payments only:\nPayment: $555/month\nPayoff: 120 months\nTotal interest: $16,612\n\nWith $200/month extra ($755 total):\nPayoff: 75 months (6.25 years)\nTotal interest: $9,819\n\nSavings:\nTime saved: 45 months (3.75 years)\nInterest saved: $6,793\n\nImpact of first extra $200:\nGoes entirely to principal (interest already covered)\nReduces future interest on that $200\nAccelerates payoff exponentially
Result:$200 extra saves $6,793 and 3.75 years
Frequently Asked Questions
What are current federal student loan rates?
2024-25 rates: Undergraduate Direct: 6.53%, Graduate Direct: 8.08%, PLUS (Parent/Grad): 9.08%. Rates set annually based on 10-year Treasury. Once disbursed, rate is fixed for life of that loan. Private loans vary by lender and credit.
Should I pay off student loans early?
Consider: If rate >6-7% and you've maxed 401k match, extra payments make sense. If rate <4-5%, investing may provide better returns (but less certainty). No federal prepayment penalties. Psychological value of being debt-free is real but not quantifiable.
How does Public Service Loan Forgiveness (PSLF) work?
120 qualifying payments (10 years) while working full-time for government or qualifying nonprofit → remaining balance forgiven tax-free. Must be on income-driven plan. Recent reforms made more payments qualifying. ~$42 billion forgiven as of 2024. Track on MOHELA.
Should I refinance my student loans?
Refinancing replaces federal loans with private. Pros: potentially lower rate if you have good credit/income. Cons: lose federal protections (IDR, PSLF, forbearance, forgiveness). Only refinance if: not pursuing PSLF, comfortable losing protections, and rate reduction is significant (2%+).