Calculator
Loan Interest Calculator
Use this tool to total the interest on a fixed-rate loan. Give it an amount, a rate and a term, and it reports the monthly payment, the interest across the life of the loan and the total repaid.
Enter your numbers and press Calculate. Nothing you type leaves your browser.
How this calculator works
The tool adds up the interest you would pay over the life of a fixed-rate loan, on the assumption that every payment is made on time.
M = P * r * (1 + r)^n / ((1 + r)^n - 1)
Total interest = (M * n) - P.
- P = amount borrowed
- r = monthly rate = annual rate / 12 / 100
- n = number of monthly payments
Both the rate and the term push interest up. Sending extra money to principal, or taking a shorter term, brings it down.
You supply the rate here, because it depends on the lender and on your credit profile. Type any rate you want to examine.
Common questions
Does total interest equal the APR?
It does not. Total interest is a dollar figure for the whole loan. The APR is an annualized percentage that also takes upfront fees into account.
What lowers the total interest?
Sending extra to principal, taking a shorter term, or finding a cheaper rate. Each one trims the balance, the number of months, or the monthly cost of the money.
Is the rate assumed to be fixed?
Yes. The math holds the rate steady for the full term. With a variable-rate loan, the cost moves as the rate does.
Why does a longer loan carry more interest?
Interest accrues across more months, even though each individual payment shrinks. Those smaller payments usually add up to more.