Student Loan Calculator
Enter your loan balance and rate for the standard 10-year plan, then add your income and family size for a simplified income-driven estimate — both update as you type, side by side, so you can see the real trade-off between a lower payment now and a longer timeline.
How this calculator works
The standard plan uses the same amortization math as any fixed-rate loan: a level payment over 120 months that fully retires the balance, with the interest share of each payment shrinking as the balance falls. The income-driven side works differently — it doesn't care about your balance or rate at all. It estimates discretionary income as your annual income minus 150% of a poverty-line figure for your household size, then takes a percentage of that (10%, 15%, or 20% — common percentages used by real federal IDR plans) and divides by 12. That mirrors the general structure of real income-driven plans without claiming to reproduce any single plan's exact rules, since those rules and thresholds change over time.
Worked example
A $35,000 balance at 6.5% interest on the standard 10-year plan comes to a monthly payment of $397.42, with $12,690.15 in total interest ($47,690.15 paid in all). Now say the borrower earns $45,000 a year with a family size of 1: the poverty-line figure is $15,060, so 150% of that is $22,590, leaving discretionary income of $45,000 − $22,590 = $22,410. At 10% of that, the income-driven estimate is ($22,410 × 0.10) ÷ 12 = $186.75 a month — $210.67 less than the standard payment. Kept up for 20 years with no forgiveness and no income change, that's a raw total of $186.75 × 240 = $44,820 — in this case actually less than the standard plan's $47,690.15, though that won't always be true at higher incomes or longer balances, which is exactly why comparing both numbers matters.
Frequently asked questions
How is the standard 10-year payment calculated?
The same amortization formula every fixed-rate loan uses: M = P × r ÷ (1 − (1 + r)⁻ⁿ), where P is your balance, r is your annual rate ÷ 12, and n is 120 monthly payments. It's the federal Standard Repayment Plan's default term, and the baseline this tool compares income-driven repayment against.
What exactly is the income-driven estimate based on?
It mirrors the general shape of real federal income-driven repayment plans: your discretionary income is your annual income minus 150% of a poverty-line figure for your family size, and your estimated payment is a percentage of that (you pick 10%, 15%, or 20%, common real-plan percentages) divided by 12. This is a simplified estimate, not a specific named plan's exact calculation — real plans have more rules than fit in a calculator. Check studentaid.gov for your exact numbers.
How accurate is the poverty-line number you use?
We use a 2024-style federal poverty guideline of $15,060/year for a single-person household, plus roughly $5,380 for each additional family member. Real guidelines update annually, differ by state (Alaska and Hawaii use higher figures), and are published by HHS — treat our constant as a reasonable approximation for comparing scenarios, not a live-updated figure.
Does the 20-year IDR total include loan forgiveness?
No — that's a real limitation of this tool. Several federal IDR plans forgive the remaining balance after 20–25 years of qualifying payments, which could make the true lifetime cost far lower than the raw number shown here. We show idrMonthly × 240 honestly, as the total you'd pay if you kept making that exact payment for 20 years with no forgiveness and no income changes — useful for comparing monthly cash flow, not a precise lifetime-cost forecast.