Student Loan Calculator

How this is calculated

M = P·r(1+r)ⁿ ÷ ((1+r)ⁿ − 1)   where r = rate ÷ 12, n = years × 12

Worked example: $30,000 at 6% over 10 years → about $333/month and roughly $10,000 of interest. It assumes a fixed rate and equal payments; variable-rate and income-driven plans differ.

Before you overpay

Student loans sometimes carry forgiveness, subsidised interest, or income caps that make aggressive repayment counterproductive. Model the plain numbers here, then check the specific rules of your loan.

Term length is the lever that costs the most

Extending a study loan from ten years to twenty roughly halves the monthly payment and far more than doubles the total interest, because the balance stays large for twice as long. That trade is sometimes the right one — a lower payment can be the difference between coping and defaulting in the first years of a career — but it should be made deliberately, with the total cost visible, rather than accepted because the monthly figure looked comfortable.

Move the term slider and watch the interest figure rather than the payment. The payment is what you feel each month; the interest is what the decision actually costs.

Subsidised, unsubsidised and the interest that grows while you study

The most expensive detail in student lending is when interest starts. On subsidised loans, interest may not accrue while you are studying. On unsubsidised loans it usually does, and if it is capitalised — added to the balance at the end of the grace period — you begin repaying a larger loan than you borrowed and then pay interest on that interest. A four-year degree can add a meaningful percentage to the principal before the first payment is due.

Where the rules allow it, paying even the interest during study prevents capitalisation entirely and is usually the highest-return small payment available to a student.

Income-driven plans change the calculation completely

Where repayment is a percentage of income above a threshold rather than a fixed instalment, this amortization model does not describe your loan. Under such plans the balance can grow despite regular payment, forgiveness may cancel the remainder after a set period, and paying extra can be actively counterproductive — money volunteered toward a balance that was going to be forgiven is simply gone. The UK's graduate repayment system and several US plans work this way.

Model the plain amortization here to understand the shape of a conventional loan, then check the actual rules of your scheme before overpaying anything.

Refinancing, and what you give up

Refinancing government loans into private ones can lower the rate and will usually forfeit the protections that came with them: income-driven repayment, deferment, forbearance and any forgiveness path. That is often a poor trade for a modest rate reduction. Refinancing private loans into cheaper private loans carries less risk, since there were fewer protections to lose.