Student Loan Interest Costs Across 45 Scenarios
Three balances, five rates, three terms. Each cell shows the total interest you would pay over the life of the loan, with the monthly payment underneath. No fees, no capitalization, no variable rate: just the baseline.
10 Years
| Balance | 4% | 5% | 6% | 7% | 8% |
|---|---|---|---|---|---|
| $20,000 | $4,299 $202/mo | $5,456 $212/mo | $6,645 $222/mo | $7,866 $232/mo | $9,119 $243/mo |
| $40,000 | $8,598 $405/mo | $10,911 $424/mo | $13,290 $444/mo | $15,732 $464/mo | $18,237 $485/mo |
| $60,000 | $12,896 $607/mo | $16,367 $636/mo | $19,935 $666/mo | $23,598 $697/mo | $27,356 $728/mo |
15 Years
| Balance | 4% | 5% | 6% | 7% | 8% |
|---|---|---|---|---|---|
| $20,000 | $6,629 $148/mo | $8,469 $158/mo | $10,379 $169/mo | $12,358 $180/mo | $14,403 $191/mo |
| $40,000 | $13,258 $296/mo | $16,937 $316/mo | $20,758 $338/mo | $24,716 $360/mo | $28,807 $382/mo |
| $60,000 | $19,886 $444/mo | $25,406 $474/mo | $31,137 $506/mo | $37,073 $539/mo | $43,210 $573/mo |
20 Years
| Balance | 4% | 5% | 6% | 7% | 8% |
|---|---|---|---|---|---|
| $20,000 | $9,087 $121/mo | $11,678 $132/mo | $14,389 $143/mo | $17,214 $155/mo | $20,149 $167/mo |
| $40,000 | $18,174 $242/mo | $23,356 $264/mo | $28,777 $287/mo | $34,429 $310/mo | $40,298 $335/mo |
| $60,000 | $27,261 $364/mo | $35,034 $396/mo | $43,166 $430/mo | $51,643 $465/mo | $60,447 $502/mo |
Each cell: total interest over the full term, then the monthly payment.
What the Grid Shows
Term doubles the interest
At 6% on $40,000, a 10-year term costs $13,290 in interest. Stretch it to 20 years and the interest is $28,777. The monthly payment falls from $444 to $287, but you pay $15,487 more to get there.
Rate compounds over time
At 20 years on $40,000, 4% costs $18,174 and 8% costs $40,298. Doubling the rate more than doubles the interest. On a short term the gap is smaller, which is why a high rate hurts most when the loan runs long.
Balance scales, rate does not
Double the balance and the interest roughly doubles. Double the rate and it more than doubles. At 8% over 20 years, $60,000 costs $60,447 in interest, more than the amount borrowed.
How These Numbers Are Calculated
Every cell uses the standard fixed-rate amortization formula:
Payment = P × r / (1 - (1 + r)-n)
P is the balance, r is the annual rate divided by 12, and n is the term in months. Total interest is the sum of all payments minus the amount borrowed. The model assumes a fixed rate, monthly payments, no fees, and no interest capitalization. Those assumptions matter: a capitalized balance or a variable rate will produce different numbers.
These are estimates for planning, not a quote. Confirm your own terms with your servicer or the Loan Simulator at StudentAid.gov.
Next Step
To run your own balance instead of reading a grid, use the interest calculator or the payoff calculator. To see what extra payments do to the total, use the extra payment calculator, and for the mechanics behind the numbers, read how amortization works.