Finance
Student Loan Payoff Calculator
See your payoff date and total interest. Test how a target monthly payment, lump sum, or refinance rate accelerates payoff.
How this is calculated
Standard amortization, solved for time. Given a balance, an interest rate, and a fixed monthly payment, the payoff date is:
n = -log(1 - (B · r) / M) / log(1 + r)
where B is balance, r is the monthly rate, and M is the monthly payment.
Three ways to accelerate
- Higher payment: every extra dollar goes to principal.
- Refinance: a lower rate cuts total interest, often dramatically.
- Lump sum: apply windfalls (tax refund, bonus) directly.
Federal forgiveness programs (PSLF, IDR) aren't modeled — outcomes depend on employer and policy. Use this for private loans or as the worst-case for federal.
Frequently asked
- Yes — switch the rate field to your refinance rate to see the difference in total interest. We don't model federal forgiveness programs (PSLF, IDR) since outcomes depend on employer and policy.