How to Calculate the Real Interest Rate
The real interest rate equals the nominal interest rate minus the inflation rate (the Fisher equation).
The Real Interest Rate formula
Calculator
Enter the nominal interest rate and inflation, and get the real interest rate plus the exact Fisher value.
The stated, money interest rate on the loan or bond.
Expected inflation for forward-looking decisions, actual inflation after the fact.
Money lent grows 4% faster than prices, so savers gain purchasing power.
- Exact Fisher real rate
- 3.92%
- Real return reading
- Positive real return
((1 + nominal) ÷ (1 + inflation)) − 1. AP accepts the subtraction shortcut above.
How to calculate Real Interest Rate, step by step
- 1Find the nominal interest rate. The stated, money interest rate on the loan or bond.
- 2Find the inflation rate. Expected inflation for forward-looking decisions, or actual inflation after the fact.
- 3Subtract. Real rate = nominal rate − inflation rate.
Worked example: Real Interest Rate
If the nominal interest rate is 6% and inflation is 2%, the real interest rate = 6% − 2% = 4%.
Expected and actual are different numbers
The rate written into a loan is set using the inflation people EXPECT. What actually happens decides who came out ahead, and the two rarely match.
A lender writing a 6% loan while expecting 2% inflation is planning on a 4% real return. If inflation turns out to be 5%, the real return was 1%. The lender lost, the borrower gained, and neither did anything differently.
That is the whole mechanism behind unexpected inflation redistributing from lenders to borrowers, and it is why the effect only works when the inflation is unexpected. Once lenders expect 5%, they charge 9% and the real return is back where they wanted it, which is the Fisher effect: nominal rates move roughly one for one with expected inflation.
It also explains why deflation is dangerous for debtors. With a 3% nominal rate and prices falling 1%, the real rate is 4%, and the debt gets harder to repay in real terms every year.
Real Interest Rate questions
Why does the real interest rate matter?
It reflects the true cost of borrowing and reward for saving in terms of purchasing power, which is what drives investment and saving decisions.
What is the Fisher effect?
Over time, nominal interest rates tend to move one-for-one with expected inflation, keeping the real rate relatively stable.
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