Business loan interest rate is influenced by different factors such as business loan type, the lender's policy, and your eligibility as a borrower. However, the traditional bank loan interest rate is 3% - 7%, while online loans range from 11% - 44%. You can calculate your loan interest by multiplying the monthly or weekly interest on your loan by the number of months or weeks of your loan duration. A business loan calculator is an easier alternative for calculating interest on your business loan.