DIY Cost Tools
Student Loan Calculator
FINANCIAL CALCULATOR
Estimate the required payment, faster payoff time, total interest, and time saved when making extra monthly student loan payments.
How it works
The required payment uses fixed-rate amortization. The payoff simulation applies interest monthly and sends the extra payment directly toward the balance.
Formula
Required payment = principal × r(1+r)ⁿ ÷ ((1+r)ⁿ − 1)
Important limits
- Variable rates, capitalization, deferment, forgiveness, income-driven plans, fees, and tax effects are excluded.
- Confirm that your servicer applies extra payments to principal as intended.
- Federal loan benefits can be valuable; compare options before refinancing or prepaying.
Frequently asked questions
Does an extra payment reduce interest?
In this model, yes, because it lowers principal sooner.
Why can my servicer’s number differ?
Daily interest, rounding, payment dates, fees, and capitalization rules can change the result.
Reviewing student-loan estimates
Use the current principal balance, interest rate, and remaining term for a repayment estimate. Interest capitalization, fees, deferment, variable rates, and repayment-plan rules can make an actual servicer schedule differ from a basic fixed-payment calculation.
Compare both the monthly payment and total interest. Extending the term may reduce the payment while increasing lifetime cost. Extra payments generally help most when applied to principal, but confirm the servicer’s instructions and whether any special benefit or forgiveness program could be affected. Federal and private loans can have very different protections, repayment options, and refinancing consequences. Treat the result as an estimate and verify decisions with official loan documents and the current servicer.
Review notes
The schedule uses monthly compounding and a fixed payment. Last reviewed September 30, 2026.