Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Estimated monthly IDR payment
$176
Income exempted from payment calc
$33,885
Discretionary income used
$21,115
Estimated annual payment
$2,112
Psst — share this and help Rex grow
One click, a permanent link with your numbers baked in.
How to use this
- 1Enter adjusted gross income ($).
- 2Enter family size.
- 3Enter idr plan.
- 4Read your estimated monthly idr payment on the right — it updates as you type.
- 5Hit Share to keep the scenario or send it to someone.
About this calculator
Income-driven repayment plans set your federal student loan payment as a percentage of discretionary income rather than the loan balance and standard term. Discretionary income is generally your adjusted gross income minus a poverty-line-based exemption — typically 150% or 225% of the federal poverty level for your family size, depending on the plan. Older plans like IBR and PAYE use 10-15% of discretionary income, while the newer SAVE plan uses a lower percentage (5-10%, split by undergraduate vs. graduate debt) and shelters more income before any payment is due, often producing a $0 payment for lower earners. This calculator estimates your monthly payment under a generic IDR formula using your AGI, family size, and the plan's percentage and poverty multiplier, so you can compare roughly what different IDR plans would charge before applying through your loan servicer.
Worked example
Using the values the calculator loads with:
Inputs
- Adjusted gross income: 55000 $
- Family size: 1
- IDR plan: SAVE (225% FPL, 10% undergrad)
Results
- Estimated monthly IDR payment: $176
- Income exempted from payment calc: $33,885
- Discretionary income used: $21,115
- Estimated annual payment: $2,112
What each field means
Inputs
- Adjusted gross income ($)
- The adjusted gross income used in the calculation, measured in $. Starts at 55000 $ so you have a working example on load.
- Family size
- The family size used in the calculation. Starts at 1 so you have a working example on load. Accepted range: 1–8.
- IDR plan
- Pick the option that matches your situation — the maths changes per option. Choices: SAVE (225% FPL, 10% undergrad), PAYE (150% FPL, 10%), IBR (150% FPL, 15%).
Results
- Estimated monthly IDR payment
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Income exempted from payment calc
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Discretionary income used
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Estimated annual payment
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Why is SAVE's payment often lower than other plans?
SAVE shelters 225% of the federal poverty line before counting any income toward the payment calculation, compared to 150% for older plans like PAYE and IBR, and it also charges a lower percentage (as low as 5% for undergraduate-only debt). Together this means many low-to-moderate earners owe $0 or a much smaller payment under SAVE than they would under older IDR plans.
Does my spouse's income count?
If you file taxes jointly, your spouse's income and family size are generally included in the calculation for most plans, which can raise your payment substantially. Filing separately can exclude spousal income for some plans (notably not always SAVE in every scenario), but often costs more in overall taxes, so it's a real tradeoff to model carefully.
What happens to the remaining balance after making IDR payments for years?
Federal IDR plans forgive the remaining balance after a set number of qualifying payments, typically 20-25 years depending on the plan and whether the debt is undergraduate or graduate. Under current tax law, forgiven IDR balances are treated as taxable income in the year forgiven (with an exception through 2025 under a temporary tax provision), so plan for that eventual tax bill.
Is this payment locked in permanently?
No, IDR payments are recalculated annually based on updated income and family size, so your payment can go up or down each year as you recertify. Missing recertification can bump you to a higher standard payment or capitalize interest, so mark your recertification date.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Student Loan IDR Payment Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/student-loan-idr-payment
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/student-loan-idr-payment" target="_blank" rel="noopener">Student Loan IDR Payment Calculator — RevenueLab</a> (2026).</p>
Source: [Student Loan IDR Payment Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/student-loan-idr-payment) (2026).