Student loan repayment isn’t one formula — it’s a choice, and most calculators only show you one side of it. Our new student loan calculator puts the standard 10-year plan and a simplified income-driven repayment (IDR) estimate side by side, so you can actually see the trade-off instead of guessing at it.
The standard side uses the same amortization math as any fixed-rate loan. The income-driven side estimates discretionary income from your annual income, family size, and a poverty-line figure, then applies a payment percentage you choose — 10%, 15%, or 20%, the percentages real federal IDR plans commonly use. On a $35,000 balance at 6.5%, the standard plan runs $397.42 a month; for a single borrower earning $45,000, the 10% income-driven estimate comes out to $186.75 a month — over $200 less, stretched over a much longer timeline.
We’re upfront about the limits: this is a simplified estimate, not any specific named plan’s exact calculation, and the 20-year raw total we show doesn’t subtract loan forgiveness that real IDR plans can apply after 20–25 years of qualifying payments. For your exact numbers, check studentaid.gov.
As with every tool here, results update as you type, your inputs live in the link so you can share a scenario, and the math runs entirely in your browser. You can also embed the calculator with one iframe.