Real Interest Rate
The real interest rate is the nominal interest rate adjusted for inflation, representing the actual purchasing power of interest earned or paid on borrowed or invested funds; it equals the nominal rate minus the expected or actual inflation rate.
The distinction between real and nominal interest rates was one of the most fundamental in macroeconomics and finance. The nominal interest rate was the stated or quoted rate — for example, the RBI's repo rate of 6.5 percent or a bank's fixed deposit rate of 7.5 percent. The real interest rate adjusted this nominal figure for the erosion of purchasing power caused by inflation. If a bank paid 7.5 percent on an FD but inflation was 6 percent, the depositor's real return was approximately 1.5 percent — their purchasing power grew by only 1.5 percent in real terms despite earning 7.5 percent in nominal terms.
The precise relationship was given by the Fisher equation, named after economist Irving Fisher: (1 + nominal rate) = (1 + real rate) × (1 + inflation rate). For typical Indian inflation and interest rate levels, the simpler approximation worked reasonably well: Real Rate ≈ Nominal Rate − Inflation Rate. For more precision with higher rates, the full Fisher equation was required.
The concept of ex-ante (expected) versus ex-post (realised) real interest rates was important in practice. An ex-ante real rate used expected inflation at the time of the lending/borrowing decision. An ex-post real rate used actual inflation that was subsequently realised. If inflation turned out higher than expected, borrowers benefited (they repaid in depreciated currency) while lenders/savers lost real purchasing power — this was the "inflation tax" on savings.
The RBI monitored real interest rates as an important indicator of the stance of monetary policy. A positive real policy rate (repo rate above CPI inflation) indicated restrictive monetary conditions — borrowing was genuinely expensive in real terms and the policy was acting to cool demand. A negative real policy rate (repo rate below CPI inflation) indicated accommodative conditions — borrowing was cheap in real terms and the policy was stimulative. During 2020–2022, India's real policy rate was significantly negative as inflation rose sharply while the RBI kept the repo rate at 4 percent to support COVID-affected growth.
For household financial planning, the real return on savings was the economically meaningful figure. Bank fixed deposits offering nominal rates of 6–7 percent with CPI inflation at 5–6 percent yielded real returns of 0–2 percent. After considering income tax on FD interest (at the investor's slab rate), the after-tax real return was frequently negative for investors in the 30 percent tax bracket, creating a powerful incentive for higher-allocation to real assets (gold, property) and equity as inflation hedges over long horizons.
The real interest rate also played a central role in corporate investment decisions. Firms evaluated capital expenditure projects by comparing their expected real return on investment against the real cost of capital. High real interest rates raised the hurdle rate for investment, potentially dampening capex cycles and long-term growth. The relationship between real interest rates and investment was one of the key transmission mechanisms through which monetary policy influenced economic activity in India.