Effective Interest Rate (EIR) is the actual annual interest rate that reflects the true cost or return of a financial product after considering compounding and additional charges.
Effective Interest Rate (EIR) gives a more accurate picture of the real interest paid or earned compared to the nominal (stated) rate. It takes into account the effect of compounding frequency (monthly, quarterly, etc.) and any additional fees or charges.
The formula is:
EIR = (1 + r/n)ⁿ − 1
Where:
EIR is important because it allows borrowers and investors to compare different financial products fairly, even if they have different compounding methods.
Understanding EIR helps in making informed decisions about loans, fixed deposits, credit cards, and other financial instruments.
"If a loan has a nominal interest rate of 12% compounded monthly, the effective interest rate will be higher than 12% due to compounding, making the actual cost of borrowing more."