Introduction to income-driven student loan payments
This calculator estimates a federal student loan payment using an income-driven repayment, or IDR, approach. It begins with your adjusted gross income, family size, selected poverty guideline, and plan percentage. It then compares the income-based amount with a 10-year standard payment when the optional cap applies. Finally, it simulates the loan month by month to estimate total paid, unpaid interest, payoff timing, and the balance that might remain at the selected forgiveness horizon.
An IDR payment behaves differently from a conventional loan payment because income, rather than the amount borrowed, primarily determines the required bill. Two borrowers with different balances can therefore receive the same income-based payment. The payment can also be lower than the interest accruing each month. In that situation, called negative amortization, the borrower pays as required while the total amount owed continues to rise.
The projected remaining balance is labeled as possible forgiveness for planning purposes. It is not a promise that the balance will be discharged. Eligibility depends on the loans, repayment plan, qualifying-payment history, recertification, and rules in force at the relevant time. Use the estimate to understand relationships and compare scenarios, then verify an enrollment or payoff decision with Federal Student Aid and your servicer.
Inputs and units for the IDR estimate
Choose the plan model first because it pre-fills the poverty-guideline multiple, payment percentage, term, and standard-payment cap. The older-borrower IBR model uses 15% of discretionary income and a 25-year term. The newer-borrower IBR model uses 10% and 20 years, subject to eligibility requirements. The ICR model uses the 100% poverty basis and a 20% payment share, although this page does not implement ICR’s separate 12-year alternative calculation. Custom mode lets you explore other assumptions without presenting them as an official plan.
Enter loan balance as current principal in dollars and interest rate as an annual percentage rate, so 5 means 5%, not 0.05. Enter adjusted gross income as an annual dollar amount from a tax return or reasonable projection. AGI is not the same as monthly take-home pay or gross salary. Family size must be a whole number of at least one and is used to select the poverty threshold.
The discretionary income basis protects a multiple of the poverty guideline before the plan percentage is applied. The payment percentage is entered as a percent, such as 10. The forgiveness term is entered in years, not months. When the cap box is selected, the calculated IDR amount cannot exceed the estimated payment needed to amortize the entered balance over 120 months.
How to use the student loan IDR calculator
Select a plan, poverty-guideline year, and region, then enter the balance, APR, annual AGI, and family size. Review the pre-filled percentage, poverty basis, term, and cap before selecting Calculate. The results identify the poverty guideline used, annual discretionary income, required monthly payment, standard comparison payment, first-month interest, total paid, and projected ending balance.
Compare the required payment with first-month interest. A lower payment signals negative amortization at the start of the projection. If the required payment exceeds interest, the excess can eventually reduce principal. Run several scenarios by changing one input at a time. For example, test current AGI, a lower-income year, and a possible future salary so you can see which assumption drives the result. Use Reset inputs when you want to restore the initial plan settings and clear the output.
Formulas for discretionary income and monthly payment
The calculator first builds the poverty guideline from a one-person base plus an increment for each additional family member. It subtracts the selected multiple of that guideline from AGI and never allows discretionary income to fall below zero. If m is the poverty multiple and p is the payment percentage expressed as a decimal, the monthly payment is:
The standard comparison uses ordinary amortization. Here P is principal, i is the monthly interest rate, and n is 120 months:
A zero discretionary-income result produces a $0 required payment. The simulation still accrues interest because it does not model an interest subsidy. If the cap is enabled and the income-based result is above the standard payment, the standard amount becomes the required payment shown.
| Model | Poverty basis | Income share | Term | Standard cap |
|---|---|---|---|---|
| IBR, borrowed before July 1, 2014 | 150% | 15% | 25 years | Yes |
| IBR, eligible new borrower on or after July 1, 2014 | 150% | 10% | 20 years | Yes |
| ICR educational model | 100% | 20% | 25 years | No |
| Custom educational model | Editable | Editable | Editable | Editable |
Poverty guidelines used: The calculator contains 2024, 2025, and 2026 values for the contiguous states and D.C., Alaska, and Hawaii. For 2026, the contiguous-state base is $15,960 for one person and the increment is $5,600 for each additional person. Alaska and Hawaii use their own higher values. The selected year is held constant throughout the projection even though HHS normally publishes new guidelines annually.
How the balance and forgiveness simulation works
Each simulated month charges interest on principal at APR ÷ 12. The payment covers current interest first, then previously unpaid interest, and finally principal. If the payment is below current interest, the shortfall is added to accrued unpaid interest while principal remains unchanged. Unpaid interest is kept separate rather than automatically compounded into principal every month.
This distinction matters over a 20- or 25-year horizon. Federal loans generally use simple daily interest, although unpaid interest may capitalize after particular events. The calculator does not model daily timing, capitalization events, subsidies, payment pauses, servicer rounding, or changes in plan rules. If principal plus unpaid interest reaches zero, the projection stops early. Otherwise, their sum at the selected horizon is reported as projected forgiveness.
Worked example: $50,000 at 5% with a family of two
Assume a $50,000 balance, 5% APR, $45,000 AGI, family size two, the 2026 contiguous guideline, a 150% poverty basis, a 10% payment share, and a 20-year term. The family-of-two poverty guideline is $21,560. Protected income is 1.5 × $21,560, or $32,340. Discretionary income is therefore $45,000 − $32,340 = $12,660.
The monthly IDR estimate is $12,660 × 10% ÷ 12 = $105.50. First-month interest is $50,000 × 5% ÷ 12 = $208.33. Because the payment is $102.83 below interest, principal does not fall and unpaid interest begins to accumulate. If income and all other assumptions remain fixed for 240 months, total scheduled payments are $25,320, while a substantial balance remains for the forgiveness estimate.
The standard 10-year payment is about $530.33 per month. Raising AGI to $60,000 would increase discretionary income to $27,660 and the IDR payment to $230.50. That amount exceeds first-month interest, so the modeled balance starts amortizing instead of growing. This comparison illustrates why AGI, family size, and the forgiveness horizon can matter more than the original balance when evaluating an IDR strategy.
Interpreting the results: Higher AGI or a higher payment percentage should increase the payment, while a larger family size generally reduces it. A projected forgiven amount is an ending balance, not a guaranteed financial benefit. Forgiveness may depend on qualifying months and may have federal or state tax consequences under the law applicable at that time. This page does not estimate taxes.
Limitations and practical IDR planning assumptions
The estimate holds income, family size, interest rate, poverty guideline, payment percentage, and plan terms constant. Real payments are normally recalculated after annual recertification, so raises, unemployment, marriage, changes in filing status, and additional dependents can materially alter the path. The model also treats the balance as one loan with one rate. A weighted-average rate can be a useful approximation for several loans, but it cannot reproduce every allocation and subsidy rule.
For practical planning, begin with the AGI from your latest return, then run a second estimate using expected income. If loans have different rates, calculate a balance-weighted average or model them separately elsewhere. Confirm which income and family-size rules apply to a spouse or dependent before relying on the output. Most importantly, compare the cumulative cash paid with the uncertainty attached to eventual forgiveness rather than looking only at the lowest monthly payment.
Input checks: Enter 6.5 for a 6.5% APR, annual rather than monthly AGI, a whole-number family size, 10 for a 10% payment share, and 20 for a 20-year term. A $0 payment can be a valid mathematical result. A rapidly growing balance can also be internally consistent when the required payment does not cover interest.
This educational model is not financial, legal, or tax advice. IBR eligibility depends on borrowing history, and the ICR result shown here includes only the 20%-of-discretionary-income arm. SAVE and PAYE are omitted because their availability and terms have been affected by litigation and policy changes. Check the current official plan menu before making a repayment decision.
Sources for IDR rules and poverty guidelines
- Federal Student Aid — Income-Driven Repayment Plans
- HHS — Poverty Guidelines
- 34 CFR 685.221 — Income-based repayment
- 34 CFR 685.209 — Income-contingent repayment
- Federal Student Aid — Standard Repayment Plan
- Federal Student Aid — Interest and capitalization
Data note: This page includes HHS poverty-guideline scenarios through 2026 and was reviewed August 5, 2026. Regulations and operational plan availability can change after publication.
Common questions about this IDR projection
What does this IDR calculator estimate?
It estimates an income-based monthly payment and simulates repayment to show total paid, unpaid interest, payoff timing, and a possible remaining balance at the selected horizon.
What is discretionary income here?
It is AGI minus the chosen multiple of the poverty guideline for the selected year, region, and family size. Negative results become zero.
Can the projected balance grow while payments are made?
Yes. If the payment is below monthly interest, the shortfall accumulates as unpaid interest. This is negative amortization.
When is the standard-payment cap applied?
The calculator applies it when the checkbox is selected and the uncapped income-based amount exceeds the estimated 10-year standard payment.
Why are SAVE and PAYE not listed?
Their availability and terms have faced litigation and policy changes. This static page focuses on editable IBR, ICR, and custom educational models.