What is Nominal Interest Rate?
The nominal interest rate is the stated or quoted rate of interest on a loan, deposit, or financial instrument before adjusting for inflation or for the effect of compounding more frequently than annually. It is the headline rate shown in loan and savings advertisements but does not reflect the true economic cost or return.
How It Works
- Nominal Rate = Real Rate + Expected Inflation (Fisher equation, approximate).
- When compounding happens more than once per year, the effective rate exceeds the nominal.
- Effective Annual Rate = (1 + nominal/m)^m – 1, where m is compounding frequency.
- Use the nominal rate for stated terms, the effective rate for true cost comparisons.
- Inflation erodes the purchasing power of nominal returns over time.
Saudi Context
Saudi consumer financing products quote nominal annual rates (and required APR disclosures). SAMA publishes SAIBOR as the benchmark short-term nominal rate for SAR-denominated lending. Because the SAR is pegged to the USD, Saudi nominal rates closely track US Fed Funds policy adjusted for local liquidity and country risk.
Example
A bank advertises a 12% nominal annual rate on a personal loan, compounded monthly. Monthly rate = 1%. Effective annual rate = (1.01)^12 – 1 = 12.68%. The borrower’s true annual cost is 12.68%, not 12%.