Student debt calculator
Student Loan Payoff Calculator
Estimate payoff time, total interest, and how extra payments may affect a student loan balance.
How this calculator works
The calculator uses a simplified monthly amortization model. Each month, interest is estimated first, then the remaining payment reduces principal.
monthly interest = current balance x annual rate / 12
principal paid = monthly payment - monthly interest
The extra monthly payment is added to your regular payment. The lump-sum scenario first reduces the balance, then estimates payoff time using your monthly payment plus extra amount.
Worked example
Suppose your student loan balance is $38,500, your weighted average rate is 6.25%, and your current payment is $430. Adding $100 per month may move more money toward principal. A separate $2,000 one-time payment can also reduce future interest if your servicer applies it to principal.
Federal loan caution
If your loans are federal, do not use this calculator as the only decision tool. Federal repayment plans, income-driven repayment, Public Service Loan Forgiveness, deferment, forbearance, interest subsidies, and servicer rules can change the best strategy. Use official StudentAid.gov resources before changing a federal student loan plan.
Related tools & guides
- Decision guide: How to choose a student loan repayment strategy
- Compare other debts: Debt Payoff Calculator
- Plan cash flow: Monthly Budget Calculator
Frequently asked questions
How do extra payments affect student loans?
Extra payments can reduce principal faster if the servicer applies them correctly. That may shorten payoff time and reduce future interest.
Does this include income-driven repayment?
No. It does not model IDR payments, forgiveness, recertification, payment count rules, subsidies, tax outcomes, or official federal loan programs.
Should I pay extra on federal student loans?
It depends. Extra payments can save interest, but they may not be the best move if you qualify for forgiveness or need a lower payment plan.
Can I use this for private student loans?
Yes, as a simple estimate. Check your private lender's rate type, fees, autopay discounts, prepayment rules, and payment allocation instructions.
Important note
This page is educational only and is not financial, lending, credit, student aid, tax, legal, accounting, or benefits advice. It does not determine eligibility for federal repayment plans, forgiveness, deferment, forbearance, discharge, consolidation, refinancing, or borrower defense. For federal student loans, use Federal Student Aid Loan Simulator and official repayment information from StudentAid.gov repayment plans.