Transparent method
The formula
Worked example
Example inputs
How to interpret the result
Extra payment applied to a student loan removes future interest calculated on the balance it came off of, so an extra payment made early in the loan removes more total interest than the identical extra payment made later, once the balance has already shrunk on its own through years of regular payments.
Before you rely on it
What to check
Compare total interest saved at a couple of different extra-payment amounts and timings, since when the extra payment happens changes how much interest it actually removes.
The common error
Where people go wrong with student loan payoff calculator
Assuming an extra payment's benefit is the same regardless of when in the loan's life it's made. Extra payments made earlier, against a larger remaining balance, remove more total future interest than the identical payment made later.
Sensitivity evidence
How annual interest rate changes the months to payoff
| Annual interest rate | Months to payoff | Remaining interest |
|---|---|---|
| 4.5% | 43.4 months | $1,539 |
| 6.5% | 45.2 months | $2,342 |
| 8.5%worked example | 47.2 months | $3,239 |
| 10.5% | 49.4 months | $4,251 |
| 12.5% | 52.0 months | $5,406 |
Every input, tested
Which input moves the months to payoff most
| Input | Tested from | To | Months to payoff at each end | Swing |
|---|---|---|---|---|
| Monthly payment | $405 | $495 | 53.6 months to 42.2 months | 11.4 months (24%) |
| Current balance | $16,200 | $19,800 | 41.7 months to 52.9 months | 11.2 months (24%) |
| Annual interest rate | 6.5% | 10.5% | 45.2 months to 49.4 months | 4.2 months (9.0%) |
Two variables at once
Months to payoff by annual interest rate and current balance
| Annual interest rate \ Current balance | $14,400 | $18,000 | $21,600 |
|---|---|---|---|
| 4.5% | 34.2 months | 43.4 months | 53.0 months |
| 6.5% | 35.2 months | 45.2 months | 55.7 months |
| 8.5% | 36.4 months | 47.2 months | 58.9 months |
| 10.5% | 37.7 months | 49.4 months | 62.5 months |
| 12.5% | 39.1 months | 52.0 months | 66.9 months |
Step by step
The worked example, input by input
| Input | Value used |
|---|---|
| Current balance | $18,000 |
| Annual interest rate | 8.5% |
| Monthly payment | $450 |
| Months to payoff | 47.2 months |
| Remaining interest | $3,239 |
Where the inputs come from
Current balance is the principal plus any unpaid interest from the servicer's account page, annual interest rate is the loan's rate, and monthly payment is the amount you actually pay. If you have several loans, run them one at a time or combine them at a weighted rate. Note whether your payment is required or voluntary, and whether you are enrolled in an income-driven plan, in which the payment changes with income.
When the result stops applying
The estimate assumes a fixed rate and payment. Federal loans on income-driven plans may end in forgiveness before payoff, so paying faster is not always best. Interest paid on student loans may be deductible up to a limit, which lowers the effective rate. Private loans with variable rates can change the schedule.
What to compare it with
Compare with the initial schedule on the student loan payment calculator, and the refinance option on the student loan refinance page. The PSLF and income-driven repayment calculators show whether forgiveness may apply to you. The debt-free date and loan payoff pages work for other loans.
People also ask
Frequently asked questions
Should I pay off student loans early?
It depends on the rate and your other goals. Paying off a high-rate loan is a strong return, but federal loans with forgiveness options may be better left on their plan.
Is student loan interest deductible?
You may deduct up to a set amount of interest each year, with the deduction phasing out at higher incomes. Check the current limit and income range.
Do extra payments go to principal?
Only if the servicer applies them that way. Some apply extra to future payments first, so specify principal in writing or online.