Free calculator

Loan Interest Calculator

This calculator adds up the interest a fixed-rate loan charges over its whole term, assuming every payment is made on time. It also shows the payment and the total repaid.

The lowest rates are only available to the most qualified applicants.

Advertising disclosure: Loancalculated may receive a referral fee if you apply through the link above. That fee does not change the rate you are offered, and it does not change our content. We are not a lender. Read the full disclosure.

By the Loancalculated Editorial Team · Last updated 2026-09-16

Enter your numbers and press Calculate. Nothing you type leaves your browser.

Compare personal loan offers Run the numbers first

The lowest rates are only available to the most qualified applicants.

Advertising disclosure: Loancalculated may receive a referral fee if you apply through the link above. That fee does not change the rate you are offered, and it does not change our content. We are not a lender. Read the full disclosure.

How this calculator works

Interest is the price of borrowing. This tool totals it across the life of a fixed-rate loan.

Payment = P × i ÷ (1 − (1 + i)−n)

Total interest = payment × n − P.

A higher rate or a longer term raises the total. Paying extra toward principal, or choosing a shorter term, lowers it.

Enter your own rate, since pricing depends on the lender and your credit profile.

Frequently asked questions

Is total interest the same thing as the APR?
No. Total interest is a dollar figure for the whole loan. The APR is an annual percentage that also folds in upfront fees.
How do I pay less interest?
Send extra money to principal, pick a shorter term, or secure a lower rate. Each change reduces the balance, the number of months, or the monthly cost of the money.
Does this assume the rate never moves?
Yes. It holds the rate constant for the entire term. A variable-rate loan can end up cheaper or dearer as the rate resets.
Why does a longer loan cost more in interest?
You are charged interest for more months. The smaller payment is real, but the sum of all those payments is usually larger.

Related calculators