The Payday Loan Calculator will instantly calculate payday loan interest with just a click. The way a payday loan works is that you typically write a post dated check (or agree to a wire transfer from your checking account at some data in the future if its an online payday loan) and then receive an upfront lump sum for some amount less than the amount that you will pay them in the future via the post dated check or wire transfer. Enter in the total payday loan amount, the loan term in days (7 days, 14 days, 21 days, etc.) and the total payday loan fee (i.e. if you have to write a post dated check for $550 to get a payday loan of $500 then the payday loan is $550 – $500 or $50) and the Payday Loan Calculator will calculate the APR of the payday loan so you can know just how much payday loan interest you are paying and what the payday loan interest rate is. Start calculating what the interest rate for the payday loan is now!