If you don’t know your interest rate (IRR), but only have your APR, there is a way of figuring out the actual interest rate on Excel.
For this, you need to know your EMI (monthly payment), duration of the loan (number of months) and principal (amount you borrowed).
Let’s assume your EMI is 2,000 and you are paying over 5 years (60 months) on a loan of 100,000. Use Excel’s RATE function. In this example:
=RATE(60, 2000, -100000) * 12 = 7.42%
I multiplied by 12 to convert the monthly interest rate to annual. Since the payment is in months (60 months), Excel returns the interest rate in months as well.
Note that this method does not require the APR. Just the EMI, duration and principal will suffice.