What is the student loan payoff calculator?
In short
A $35,000 student loan at 6.8% on the standard 10-year plan costs about $403 per month and $13,400 in total interest. Adding $100 extra per month cuts the payoff to about 7.5 years and saves roughly $3,800 in interest. If your payment doesn't exceed the ~$198 monthly interest charge, the balance never shrinks.
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
- 1Enter your current student loan balance.
- 2Enter the loan's annual interest rate (APR).
- 3Enter your required monthly payment.
- 4Optionally add an extra monthly payment to see the time and interest saved.
- 5Review the payoff timeline, total interest, and balance chart with and without the extra payment.
The formula
- 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.
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
How long does it take to pay off $35,000 in student loans?
What happens if my payment only covers the interest?
How much does an extra $100 a month save on student loans?
Should I pay off student loans early or invest?
What is the standard student loan repayment term?
Do extra payments on student loans go to principal?
Is it better to pay off the highest-rate student loan first?
How is student loan interest calculated?
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.