What drives the cost
Student loans amortize like any other fixed loan: a level monthly payment split between interest and principal. Two levers dominate the total cost — the interest rate and the term. A $30,000 loan at 6% over 10 years costs about $9,967 in interest; stretch it to 20 years and the payment drops but total interest more than doubles. Longer terms ease monthly cash flow at a steep long-run price.
The power of extra payments
Because interest accrues on the balance, every extra dollar toward principal removes all the future interest that dollar would have generated. Try the extra-payment field: even a modest additional amount can cut months off the loan and save meaningful interest. Ask your servicer to apply extra payments to principal, not toward future installments, or the benefit is lost.
Fixed vs variable, and repayment plans
- Fixed-rate loans (this calculator's model) keep the same payment for the life of the loan — predictable and safest.
- Income-driven plans (common for government loans) cap payments at a share of income and may forgive remaining balances after many years, but often increase total interest paid.
- Refinancing can lower a high rate, but refinancing federal loans into private ones usually forfeits protections like income-driven plans and forgiveness — weigh carefully.
Where student debt fits in your plan
Low-rate student loans (say under 5%) are often worth paying on schedule while you invest and build an emergency fund. Higher-rate loans deserve more aggressive payoff. Whatever the rate, always capture any employer retirement match first — a 50–100% instant return beats prepaying almost any loan.