Student Loan Calculator
Model standard 10-year federal student loan payments, compare extended 20-year plans, estimate income-driven repayment (IDR), and calculate interest eliminated through extra monthly payments.
Student Loan Repayment Formulas & Plan Comparison
Federal student loans default to a Standard 10-Year Repayment Plan (120 months) using fixed amortization. Borrowers can also select extended terms or apply for Income-Driven Repayment (IDR) plans based on discretionary income.
Lowest total interest cost. 120 equal monthly installments pay off full principal and accrued interest.
Tied to your income rather than debt size. Forgives remaining balance after 20 to 25 qualifying years.
Federal student loans have 0% prepayment penalties. Directing an extra $100/mo cuts years off your timeline and saves thousands in compounding interest.
Loan & Repayment DetailsLive calculation
Student Loan Amortization Schedule
Monthly debt reduction and interest progression across the life of your student loan:
| Month | Payment | Principal Paid | Interest Paid | Remaining Balance |
|---|---|---|---|---|
| Month 1 | $425.8 | $222.68 | $203.13 | $37,277.32 |
| Month 2 | $425.8 | $223.89 | $201.92 | $37,053.43 |
| Month 3 | $425.8 | $225.1 | $200.71 | $36,828.34 |
| Month 4 | $425.8 | $226.32 | $199.49 | $36,602.02 |
| Month 5 | $425.8 | $227.54 | $198.26 | $36,374.47 |
| Month 6 | $425.8 | $228.78 | $197.03 | $36,145.7 |
| Month 7 | $425.8 | $230.02 | $195.79 | $35,915.68 |
| Month 8 | $425.8 | $231.26 | $194.54 | $35,684.42 |
| Month 9 | $425.8 | $232.51 | $193.29 | $35,451.9 |
| Month 10 | $425.8 | $233.77 | $192.03 | $35,218.13 |
| Month 11 | $425.8 | $235.04 | $190.76 | $34,983.09 |
| Month 12 | $425.8 | $236.31 | $189.49 | $34,746.78 |
| Month 24 | $425.8 | $252.14 | $173.67 | $31,809.17 |
| Month 36 | $425.8 | $269.03 | $156.78 | $28,674.82 |
| Month 48 | $425.8 | $287.04 | $138.76 | $25,330.56 |
| Month 60 | $425.8 | $306.27 | $119.54 | $21,762.33 |
| Month 72 | $425.8 | $326.78 | $99.03 | $17,955.12 |
| Month 84 | $425.8 | $348.66 | $77.14 | $13,892.95 |
| Month 96 | $425.8 | $372.01 | $53.79 | $9,558.71 |
| Month 108 | $425.8 | $396.93 | $28.88 | $4,934.21 |
| Month 120 | $425.8 | $423.51 | $2.29 | $0 |
10-Year Standard vs 20-Year Extended Repayment Comparison
Compare the trade-off between lower monthly payments and total lifetime interest costs:
| Loan Balance | 10-Yr Payment | 10-Yr Total Interest | 20-Yr Payment | 20-Yr Total Interest |
|---|---|---|---|---|
| $25,000 | $284 / mo | $9,064 | $186 / mo | $19,757 |
| $37,500 (US Avg) | $426 / mo | $13,596 | $280 / mo | $29,635 |
| $50,000 | $568 / mo | $18,128 | $373 / mo | $39,514 |
| $100,000 | $1,135 / mo | $36,256 | $746 / mo | $79,028 |
Frequently Asked Questions About Student Loans
What is the standard student loan repayment formula?↓
The standard student loan repayment formula is the amortized loan equation: M = P × [r(1 + r)^n] ÷ [(1 + r)^n − 1], where M is monthly payment, P is total student loan principal, r is monthly interest rate (APR / 12), and n is 120 months (10 years). For example, a $30,000 student loan at 6.5% interest over 10 years requires a fixed payment of $340.64 per month.
How much are monthly payments on $37,000 in student loans?↓
On the national average balance of $37,000 at 6.5% APR: On a standard 10-year plan (120 months), payments are $420/month with $13,415 in total interest. On a 20-year plan (240 months), payments drop to $276/month, but total interest jumps to $29,240—more than double the interest cost.
How does paying an extra $100 per month help pay off student loans?↓
Paying an extra $100/month directly against principal on a $37,000 loan at 6.5% APR shortens your payoff timeline from 10.0 years down to 7.3 years (saving 32 months of payments) and eliminates over $3,800 in interest expenses.
What is the difference between standard and income-driven repayment?↓
The standard plan is fixed over 10 years and results in the lowest total interest paid. Income-Driven Repayment (IDR) plans calculate your monthly payment as a percentage of your discretionary income (typically 5% to 10% above the federal poverty line) regardless of how much you owe, extending terms to 20 or 25 years with potential taxable or tax-free loan forgiveness at the end.
Authored by Arham Bilal
Formulas calibrated against Federal Student Aid (FSA) regulations, Department of Education standard repayment formulas, and Title IV debt amortization guidelines.
Related Financial Tools
Interconnected calculations to validate your business economics
Personal Loan & Debt Consolidation Calculator
Model monthly payments, credit score APR tiers (6.5% - 35.99%), total interest, and debt payoff savings.
Debt Payoff Calculator (Avalanche vs Snowball)
Compare mathematically optimal Avalanche vs psychological Snowball methods with extra monthly payments.
Mortgage & Loan Refinance Breakeven Calculator
Compare existing vs new interest rates, monthly savings, closing cost recovery breakeven months, and net lifetime savings.
Paycheck & Take-Home Pay Calculator
Calculate net take-home pay with 2026 federal progressive tax brackets, FICA, state tax, and pre-tax deductions.