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Loans

Student Loan Payoff Calculator

See how long your student loans take to pay off, what they really cost, and how much extra payments save.

Updated June 2026 · Editorial standards

Your loan

$
%
$
$
Time to payoff
10 years and 2 months
Total interest
$13,479
Total paid
$48,479
Interest saved
$0

At $400/month, this $35,000 loan takes 10 years and 2 months to pay off and costs $13,479 in interest. Try adding an extra payment to see the savings.

Loan balance over time

Total cost — principal vs interest

Year-by-year payoff schedule

PeriodBalancePrincipal paidTotal interest
Year 1$32,503$2,497$2,303
Year 2$29,831$5,169$4,431
Year 3$26,972$8,028$6,372
Year 4$23,911$11,089$8,111
Year 5$20,637$14,363$9,637
Year 6$17,132$17,868$10,932
Year 7$13,382$21,618$11,982
Year 8$9,368$25,632$12,768
Year 9$5,073$29,927$13,273
Year 10$476$34,524$13,476
By the KalkWise Editorial Team Reviewed for accuracy Updated June 2026

What is the student loan payoff calculator?

In short

To find how long a student loan takes to pay off, apply your monthly payment against the balance plus accrued interest each month until the balance reaches zero. A $35,000 loan at 6.8% interest with a $400 monthly payment takes about 121 months (10.1 years) to pay off and costs roughly $13,400 in total interest. Adding even $100/month extra cuts the payoff to about 7.5 years and saves around $3,800 in interest.

This student loan payoff calculator simulates your loan month by month: it shows how long the loan takes to pay off, the total interest you'll pay, and exactly how much time and money an extra monthly payment saves. It also warns you when your payment is too small to make progress against the interest.

How to use this calculator

  1. 1Enter your current student loan balance.
  2. 2Enter the loan's annual interest rate (APR).
  3. 3Enter your required monthly payment.
  4. 4Optionally add an extra monthly payment to see the time and interest saved.
  5. 5Review the payoff timeline, total interest, and balance chart with and without the extra payment.

The formula

n=−ln(1−r·PM)ln(1+r)
Months to payoff: n = −ln(1 − r × P ÷ M) ÷ ln(1 + r), where P is the balance, M the monthly payment, and r the monthly interest rate. KalkWise simulates each month individually, so extra payments are applied precisely.
n
— Number of months to pay off the loan
P
— Current loan balance
M
— Total monthly payment (required + extra)
r
— Monthly interest rate = APR ÷ 12

Worked example

The scenario

A $35,000 student loan at 6.8% APR with a $400 monthly payment and an extra $100/month applied to principal.

gives

The result

Without the extra payment: ~121 months (10.1 years) and about $13,400 in interest. With $500/month total: ~89 months (7.5 years) and about $9,600 in interest — saving roughly $3,800 and nearly 3 years.

Common use cases

  • Estimating your real student loan payoff date based on what you actually pay
  • Quantifying the interest savings from rounding your payment up by $50–$200/month
  • Checking whether your income-driven payment is even covering the monthly interest
  • Comparing aggressive payoff vs. minimum payments before deciding to invest extra cash
  • Planning a debt-free date before a major life event like buying a home

Limitations & assumptions

  • Assumes a fixed interest rate; variable-rate private loans will deviate from the projection.
  • Does not model income-driven repayment (IDR) plans, forgiveness programs, or subsidized interest pauses.
  • Federal loan fees, capitalized interest from deferment, and late fees are not included.
  • Assumes payments are made on time every month with no skipped payments.

Frequently asked questions

At 6.8% interest with a $400 monthly payment, a $35,000 student loan takes about 121 months — just over 10 years — and costs roughly $13,400 in interest, for a total repayment of about $48,400. Raising the payment to $500/month cuts the payoff to about 7.5 years and the interest to roughly $9,600.

Disclaimer: KalkWise calculators are provided for general informational and educational purposes only and do not constitute financial, investment, tax, or legal advice. Results are estimates based on the figures you enter and the assumptions described above. Actual outcomes will vary. Consult a qualified professional before making financial decisions.