Student Loan Income-Driven Repayment Calculator

Estimate IDR payments and possible forgiveness

This calculator provides a practical estimate of a federal student loan payment under an income-driven repayment (IDR) approach. You enter your loan balance and interest rate, then provide your adjusted gross income (AGI), family size, a payment percentage (for example, 10%), and a forgiveness term (for example, 20 years). The tool calculates a monthly payment from discretionary income and then simulates month-by-month repayment to estimate:

• Monthly payment based on discretionary income
• Total paid over the selected term (or until paid off)
• Remaining balance at the end of the term (shown as “forgiven” in the estimate)

Use this page to compare scenarios (for example, “What if my income increases?” or “What if my family size changes?”). The goal is not to predict the future perfectly; it is to give you a consistent way to test assumptions and understand which variables matter most.

Inputs and units (what each field means)

Use annual amounts for income and percentages for rates. If you are unsure, use your most recent tax return for AGI and your current loan statement for balance and interest rate. If you have multiple loans, you can start by entering the combined balance and a weighted-average interest rate as a rough approximation.

• Loan Balance: current principal balance (dollars).
• Interest Rate (APR %): annual percentage rate as a percent (for example, enter 5 for 5%).
• Adjusted Gross Income: annual AGI (dollars per year).
• Family Size: household size used for the poverty guideline.
• Payment Percentage of Discretionary Income: plan percentage (commonly 5%–15% depending on plan and loan type; this page uses your entered value).
• Forgiveness Term (years): number of years to simulate before forgiveness (commonly 20 or 25 years depending on plan/eligibility).

When you interpret results, keep the time basis straight: income is annual, interest is converted to a monthly rate, and the simulation runs in monthly steps. If you accidentally enter monthly income as if it were annual, the payment estimate will be far too low.

Core formula used for the monthly payment

Many IDR plans base payments on discretionary income, which is typically defined as AGI minus a plan-specific multiple of the federal poverty guideline for your family size. This calculator uses the selected plan settings and computes:

Discretionary income = max(0, AGI − planMultiplier × PovertyGuideline)
Monthly payment = (Discretionary income × p) ÷ 12

In MathML form:

If AGI is low enough that AGI − 1.5 × PovertyGuideline is negative, discretionary income is treated as zero and the calculated payment becomes $0.00. In practice, some plans also include additional rules (for example, caps relative to a standard payment), but this page focuses on a clear, explainable baseline.

Poverty guideline table used

The calculator includes poverty-guideline years through 2026 and separate regions for the 48 contiguous states and D.C., Alaska, and Hawaii. For 2026, household size 1 is $15,960 in the contiguous U.S., with higher Alaska and Hawaii values.

Source metadata: HHS poverty guidelines through 2026 and Department of Education income-driven repayment plan concepts. Effective years: 2024, 2025, 2026 poverty-guideline scenarios. Last updated on AgentCalc: May 13, 2026. Limitation: legal and policy status for repayment plans can change; verify current plan availability and terms with official sources.

How the payoff/forgiveness simulation works

After computing the monthly payment, the calculator simulates repayment for the selected number of months. Each month it adds interest and subtracts the required payment. If the required payment is below monthly interest, the unpaid interest is tracked as accrued interest and can increase the projected forgiveness amount. The payment is not automatically raised to interest unless a selected plan explicitly requires it.

Important: Real IDR rules can be more nuanced (for example, interest subsidies, capitalization rules, and plan-specific definitions). Use this as an estimate for scenario planning, and confirm final numbers with your loan servicer or official Department of Education tools.

Worked example (with realistic inputs)

Example scenario:

• Loan Balance: $50,000
• Interest Rate (APR %): 5%
• Adjusted Gross Income: $45,000
• Family Size: 2
• Payment Percentage: 10%
• Forgiveness Term: 20 years

Using the 2026 contiguous-U.S. poverty guideline for a family of 2 ($21,560), discretionary income is:

Discretionary income = max(0, 45,000 − 1.5 × 21,560) = max(0, 45,000 − 32,340) = $12,660

Monthly payment estimate:

Monthly payment = (12,660 × 0.10) ÷ 12 = $105.50

Then the calculator simulates interest and payments over 20 years to estimate total paid and any remaining balance at the end of the term. If you repeat the same example but increase AGI to $60,000, the discretionary income rises and the monthly payment increases; that typically reduces the remaining balance at the end of the term.

Tips for interpreting results

• Check the direction: Higher AGI or a higher percentage should increase the payment; larger family size should usually decrease it.
• Compare scenarios: Try two or three income levels (current, optimistic, conservative) to see how sensitive forgiveness is to income changes.
• Stress-test the term: Compare 20 vs. 25 years if you are unsure which forgiveness horizon applies to your situation.
• Know what’s not included: This estimate does not model income growth, annual recertification changes, taxes on forgiveness, or plan-specific edge cases.

Assumptions and limitations

• Income is treated as constant over the full term (no raises, unemployment, or recertification changes).
• Poverty guideline basis: selected poverty-guideline year and region, including 2026 values for the contiguous U.S., Alaska, and Hawaii.
• Interest accrual: required payment, monthly interest, accrued interest, and projected forgiveness are shown separately.
• Single-loan simplification: the model treats your balance as one loan with one interest rate.
• Educational estimate only: official payments can differ due to program rules and servicer calculations.

Introduction: Practical notes for real-world planning

Borrowers often use IDR estimates for budgeting and for comparing repayment strategies. A few practical considerations can help you use the output responsibly:

• Annual recertification: Many IDR plans require you to update income and family size periodically. If your income rises, your payment can rise; if your income falls, your payment can fall. This calculator holds income constant so you can isolate the effect of today’s inputs.
• Income definition: AGI is not the same as gross pay. Pre-tax retirement contributions, health insurance premiums, and certain deductions can affect AGI. If you are planning ahead, it can be useful to run one scenario with last year’s AGI and another with a projected AGI.
• Household size details: Household size rules can be nuanced (for example, dependents and marital status). Use the definition that applies to your filing and repayment situation, and consider running a “family size +1” scenario if you expect a change.
• Multiple loans: If you have loans with different rates, a weighted-average rate can be a reasonable first pass. For a more precise analysis, you would model each loan separately; this page intentionally stays simple.
• Forgiveness and taxes: Some forgiveness programs may have tax implications depending on current law and your state. This calculator reports a remaining balance as “forgiven” for planning, but it does not estimate any tax bill.

For best results, treat the calculator as a scenario tool: run a baseline, then change one input at a time. That approach makes it easier to see which variable is driving the outcome and reduces the chance of drawing conclusions from a single, fragile set of assumptions.

Quick sanity checks (to catch common input mistakes)

If your result looks surprising, these checks often identify the issue quickly:

• Interest rate entered as a percent: Enter 6.5 for 6.5%, not 0.065.
• Income entered annually: If you earn $4,000 per month, enter 48000 as annual AGI (or your actual AGI), not 4000.
• Family size is a whole number: Use 1, 2, 3, 4, etc. If you enter 0, the poverty guideline extension logic will not represent a real household.
• Payment percentage is a percent: Enter 10 for 10%, not 0.10.
• Term is in years: Enter 20 for 20 years, not 240.

Finally, remember that the monthly payment shown is derived from discretionary income and the selected plan. If the required payment is $0.00, monthly interest can still accrue in this educational projection unless the plan rules modeled here say otherwise.