Which plan costs less.
The Standard ten-year payment against the income-driven alternatives, computed side by side.
Income-driven formulas reflect the Repayment Assistance Plan and IBR as they apply to 2026 borrowers.
| Standard (10 years) | $431 / mo |
| IBR (10% of discretionary) | $321 / mo |
| RAP (7% of AGI) | $362 / mo |
| Discretionary income | $38,525 |
| Total paid, Standard | $51,778 |
Income-driven payments are recertified annually and rise with income. Forgiveness timelines, interest subsidies and PSLF are not modelled.
A lower payment is not a cheaper loan
Federal student loans offer a genuine choice, and the two halves of it pull in opposite directions. The Standard plan amortises your balance over ten years: the highest monthly payment, the least total interest, a fixed end date. Income-driven plans set the payment as a share of what you earn instead, which protects your cash flow and can stretch the term long enough that you pay considerably more interest overall.
The income-driven formulas differ in an important way. IBR charges 10% of discretionary income — the amount by which your AGI exceeds 150% of the federal poverty guideline for your family size — so a borrower earning near that threshold pays very little. The Repayment Assistance Plan charges a share of total AGI on a sliding scale from 1% to 10%, with a floor of $10 a month, which is simpler to predict but starts biting at lower incomes.
Payments on income-driven plans are recertified every year. A raise raises your payment; a new child or a drop in income lowers it. That responsiveness is the point, but it means the figure you see today is a snapshot, not a schedule.
Two things change the arithmetic entirely and are not modelled above: Public Service Loan Forgiveness, which can discharge the remaining balance after ten years of qualifying payments, and forgiveness at the end of an income-driven term. If either applies to you, the plan with the lowest lifetime cost is often the one with the lowest monthly payment, not the fastest payoff.
Common questions
Should I just pick the lowest payment?
Only if cash flow is tight or you expect forgiveness. Otherwise the Standard plan almost always costs less in total interest.
What counts as discretionary income?
AGI above 150% of the federal poverty guideline for your household size. It is not your take-home pay, and family size changes it materially.
Do these plans apply to private loans?
No. IBR and RAP are federal programmes. Private lenders set their own terms and rarely offer income-driven repayment.
Sources & method
The Standard plan amortises the balance over 120 months at the rate entered.
IBR charges 10% of discretionary income — AGI above 150% of the federal poverty guideline, taken here as $15,650 plus $5,500 per additional household member.
RAP charges 1% to 10% of total AGI on a sliding scale by income band, with a $10 monthly minimum.
The Index
Every calculator is built the same way: real 2026 figures, method printed at the foot of the page.