Student Loan Calculator

Capitalisation is the detail that surprises most graduates: on an unsubsidised loan, interest builds while you study and through the grace period, then joins the principal — so you start repaying more than you borrowed, and from then on you pay interest on that interest. Making even small payments during the grace period, if your lender allows it, stops that from happening. Extra payments are powerful for the opposite reason: because your regular payment already covers the month’s interest, everything extra goes straight against principal, which cuts both the balance and all the future interest it would have generated.

Interest accrued during the grace period is principal × rate × months ÷ 12, added to the balance at repayment. The monthly payment then follows the standard amortisation formula P × r × (1+r)^n ÷ ((1+r)^n − 1), where r is the monthly rate and n the number of payments.

This models a single fixed-rate loan on a standard amortised schedule. It does not cover income-driven repayment plans, loan forgiveness programmes, deferment beyond the grace period you enter, variable rates, or origination fees, all of which vary enormously by country and lender. If you hold several loans at different rates, calculate each separately or use the Debt Payoff Calculator.

Borrowing 30,000 at 6.5% with a 6-month unsubsidised grace period capitalises about 975 of interest, giving a balance of 30,975 at the first payment and a monthly payment of roughly 352 over 10 years.

1. Enter the amount borrowed and the annual interest rate.
2. Set the repayment term and the grace period in months.
3. Choose whether the loan is subsidised or unsubsidised.
4. Add any extra monthly payment to see the interest and time saved.

• Assuming the balance at your first payment equals the amount you borrowed.
• Treating a subsidised loan and an unsubsidised one as the same thing.
• Choosing a longer term for the lower payment without noticing the extra interest.
• Adding several loans at different rates together as if they were one.

The Student Loan Calculator works out your monthly payment and total interest, and — unlike a generic loan calculator — models the interest that accrues during your grace period and is capitalised onto the balance when repayment begins. It also shows what any extra monthly payment would save.

Students and graduates planning repayment, and anyone deciding whether to pay extra towards an education loan.

• Models grace-period capitalisation, which most loan calculators ignore entirely.
• Distinguishes subsidised from unsubsidised loans.
• Shows the interest and time saved by paying extra each month.
• Charts the falling balance and exports the summary as CSV.

• Estimating the monthly payment before you graduate.
• Seeing how much the grace period adds to what you owe.
• Deciding whether an extra 50 or 100 a month is worth it.
• Comparing a 10-year term with a longer one.