Student loan payment calculator guide
Student loan cost begins with principal but can grow before repayment when interest accrues. Subsidized federal loans, unsubsidized federal loans and private loans can treat school and grace-period interest differently.
This calculator models a fixed-payment scenario. Federal income-driven repayment, consolidation and forgiveness rules are eligibility-sensitive and changing; use the official Loan Simulator for current personalized results.
How to use this student loan calculator
- Enter principal and rate: Use the loan’s current fixed terms.
- Set time until repayment: Include the modeled school, grace or deferment months.
- Identify interest treatment: Select subsidized treatment only when applicable to the modeled period.
- Choose a fixed term: Use this for standard amortization comparisons.
- Use official federal tools: Check current plan eligibility, IDR payments and forgiveness separately.
Formula and variables
Pre-repayment interest is estimated with simple monthly accrual. The repayment principal is then amortized over the fixed term.
Repayment principal = original principal + capitalized accrued interest- Original principal — Amount borrowed
- Balance before modeled pre-repayment interest.
- Repayment principal — Starting repayment balance
- Principal plus accrued interest when capitalization is selected.
Worked example: $35,000 unsubsidized loan
Assume 5.5% interest, six months until repayment and a 120-month fixed term.
- Principal
- $35,000
- Pre-repayment period
- 6 months
- Term
- 120 months
- Estimate interest during the six-month period.
- Add it to principal when capitalization is selected.
- Amortize the repayment balance.
Result: Capitalization raises both the repayment balance and later interest
Exact capitalization events and subsidies depend on the loan and current rules.
Understanding your results
Pre-repayment interest
Interest estimated before scheduled repayment begins.
Repayment principal
Starting balance after selected capitalization treatment.
Fixed payment
Standard amortization scenario rather than an IDR payment.
Assumptions
- Fixed rate and monthly accrual.
- No payments before repayment unless interest is marked subsidized.
- Extra payments reduce principal.
Limitations
- IDR, PSLF and forgiveness are not projected.
- Exact disbursement and capitalization dates are simplified.
- Private loan contract terms can differ.
Common mistakes
- Borrowing the maximum without a budget.
- Confusing subsidized and unsubsidized interest.
- Ignoring interest while in school.
- Choosing private loans without comparing federal protections.
- Using stale IDR formulas instead of the official simulator.
- Using forbearance without reviewing interest and forgiveness effects.
Practical use cases
Estimate standard repayment
Model principal, interest and a fixed term.
Measure capitalization
Compare paying pre-repayment interest with adding it to principal.
Test extra payments
Estimate faster payoff after repayment begins.
Planning and decision guide
Federal and private loans are different products
Federal loans generally provide statutory protections and current federal repayment options. Private terms depend on the contract, credit underwriting and lender policies. Compare protections as well as rate.
Subsidized and unsubsidized interest
Eligible subsidized loans may receive an interest subsidy during specified periods. Unsubsidized and private loans commonly accrue interest from disbursement. Verify each loan in StudentAid.gov or its contract.
Repayment plans require current official calculations
Income-driven plans use income, family information, loan type and changing federal rules. The Federal Student Aid Loan Simulator is the appropriate source for current eligibility, projected payment and forgiveness scenarios.
Payment pauses can increase cost
Interest may accrue during deferment or forbearance and these periods can affect forgiveness progress. Ask the servicer about alternatives before pausing payments.
Borrowing decisions begin before repayment
Compare grants, scholarships, work-study, school net price and expected total borrowing. File required aid applications on time and avoid treating the offered maximum as a recommended amount.
Frequently asked questions
How much will my student loan payment be?
For a fixed plan it depends on repayment principal, rate and term. Federal IDR payments require the official Loan Simulator.
What is capitalized interest?
It is unpaid interest added to principal, after which interest can be charged on the larger balance.
Should I choose federal or private student loans?
Compare current eligibility and terms. Federal loans commonly provide protections and repayment options not guaranteed by private contracts.
Can I pay student-loan interest while in school?
Many loans allow payments before they are required. Confirm application instructions with the servicer.
Does this calculator estimate PSLF or IDR forgiveness?
No. Use StudentAid.gov because current eligibility and calculations depend on program rules and borrower history.
Sources and review
- Compare student loan repayment plans with Loan Simulator — Federal Student Aid. Accessed 2026-07-10.
- How to prepare for student loan payments — Federal Student Aid. Accessed 2026-07-10.
Reviewed 2026-07-10.