Realränta

Realränta, or the real interest rate, is the rate of interest adjusted for inflation. It represents the true cost of borrowing or the real return to lending, reflecting the purchasing power of money over time. The concept is central to financial decision making, macroeconomic policy, and the functioning of credit markets.

In theory, the real rate is related to the nominal rate and inflation through the Fisher equation. The standard (one-period) approximation is r ≈ i − π^e, where i is the nominal interest rate and π^e is expected inflation. A more exact form uses (1 + i) = (1 + r)(1 + π^e). Economists also distinguish an ex post real rate, r^p = i − π^t, where π^t is the realized inflation rate. Realränta thus depends on both borrowing costs and inflation outcomes.

Real rates influence economic activity: higher real rates tend to discourage borrowing and investment and encourage saving, while lower or negative real rates can stimulate spending and expansion. Central banks influence nominal rates, but the effective real rate also hinges on inflation expectations, which can be shaped by monetary policy, credibility, and macroeconomic conditions. The neutral or natural real rate, r*, is the real rate that would prevail when inflation is stable and output is at full employment.

Realränta is not directly observable and varies over time and across instruments. Analysts distinguish between real risk-free rates and real yields on riskier assets, both of which incorporate expectations about future inflation, risk premia, and taxes.