Student Loan Calculator
Student loans are usually repaid over ten years or more, so small changes to the payment can shift the total cost by thousands. This calculator shows your standard payment, the interest you will pay, how much sooner and cheaper an extra monthly payment makes it, and what payment you would need to be debt-free by a date you choose. It assumes a fixed rate; federal and private loans, income-driven plans and deferral rules vary, so treat the numbers as estimates.
How to use the student loan calculator
- Enter your balance, interest rate and the standard repayment term.
- Add an extra monthly payment to see the time and interest saved.
- Enter a target payoff time to see the monthly payment that would achieve it.
Formula
Payment = L × i ÷ (1 − (1 + i)−n), where L is the balance, i the monthly rate (annual rate ÷ 12) and n the number of months. With extra payments, interest is charged monthly on the remaining balance and the extra reduces principal directly.
Worked examples
The standard plan
$30,000 at 5.5% over 10 years costs $325.58 a month and $9,069.46 in total interest.
An extra $100 a month
Paying $100 extra clears the loan in 86 months (about 7.2 years) instead of 120, saves about $2,753 in interest and finishes 34 months sooner.
A 7-year target
To be debt-free in 7 years the payment is about $431.10, roughly $106 more than the standard plan.
Paying student loans wisely
How much does the term matter?
| $30,000 at 5.5% | Monthly payment | Total interest |
|---|---|---|
| 5 years | $573.03 | $4,382 |
| 10 years | $325.58 | $9,069 |
| 20 years | $206.37 | $19,528 |
A longer term lowers the payment but roughly doubles the interest between 10 and 20 years.
Where extra money helps most
If you have several loans, extra payments usually save the most when applied to the highest-interest loan first (the “avalanche” method). Some people prefer paying off the smallest balance first for motivation (the “snowball” method). Both beat paying only the minimum.
Questions to ask your servicer
- Is my rate fixed or variable?
- How are extra payments applied?
- Does interest capitalise (get added to the balance), and when?
- What repayment or forgiveness options exist for my type of loan?
Keep in mind
This tool covers a simple fixed-rate loan. Your circumstances, loan type and local rules may differ, and this is not financial advice.
Practice problems
Try these yourself first, then check your answer. The answers come from the calculator above.
- A $24,000 loan at 6% over 10 years. What is the payment and total interest?
Show answer
Standard monthly payment: $266.45 · Payment to be debt-free in 10 years: $266.45
- The same loan with $75 extra a month. How much sooner is it paid off?
Show answer
Standard monthly payment: $266.45 · Payment to be debt-free in 8 years: $315.39
Common mistakes to avoid
- Assuming extra payments are applied to principal. Ask your servicer how extra payments are applied, and to apply them to the highest-rate loan first.
- Forgetting that interest may accrue during school or deferment, raising the balance.
- Choosing a plan by the monthly payment alone. A longer term lowers the payment but raises the total cost.
Frequently asked questions
How is a student loan payment calculated?
With the amortization formula above, using the balance, the monthly rate and the number of months.
Do extra payments really help?
Yes. They reduce the balance that interest is charged on, so you finish sooner and pay less interest.
Should I pay off student loans early?
It depends on the interest rate compared with what you could earn elsewhere, your emergency fund and other debts. This tool shows the numbers; it is not financial advice.
Does this cover income-driven plans?
No. It models a fixed payment. Income-driven plans base payments on income and may forgive a balance after a period, so check with your servicer.
Reviewed September 26, 2026 by the SolveCalcPro editorial team. Found a mistake? Tell us; see our editorial policy.