Real Interest Rate Calculator
The Real Interest Rate Calculator computes real interest rate from the relation real rate = ((1 plus nominal rate over 100) divided by (1 plus inflation rate over 100) minus 1) times 100. It takes 2 inputs (nominal interest rate in %, inflation rate in %) and returns the real interest rate. Because this is a pure mathematical or physical formula rather than a jurisdiction-specific rule, the result never changes over time: the same inputs always produce the same answer, so you can rely on it whether you are checking homework, sizing a design, or sanity-checking another tool. Enter your values in the fields below and the result updates instantly; you can also share a permalink that pre-fills the exact calculation, which is useful for teaching, reports, or collaboration. For example, with nominal interest rate = 7 %, inflation rate = 3 %, the real interest rate works out to 3.883495, and the worked example further down the page shows every step so you can follow the arithmetic and reproduce it by hand. The method is the standard form documented by Federal Reserve, and the figure above each result carries the date it was last verified. This tool is general information and is not a substitute for professional engineering, medical, financial, or scientific advice; always check critical results against the primary source and your own judgement.
With Nominal interest rate = 7 %, Inflation rate = 3 %, the result is 3.883495.
Applies to: any numeric inputs. Method source: Federal Reserve, checked 2026-06-23.
The formula
real rate = ((1 plus nominal rate over 100) divided by (1 plus inflation rate over 100) minus 1) times 100
Worked example
With Nominal interest rate = 7 %, Inflation rate = 3 %:
- Divide (1 + nominal/100) by (1 + inflation/100)
- Subtract 1 and multiply by 100
- Real interest rate = 3.8834951456310662 percent
- Real Interest Rate = 3.883495
This worked example is one of the automated golden-value tests this calculator must pass before it can publish.
What this assumes
- Inputs are real numbers in the units shown.
- The result is the exact value of real rate = ((1 plus nominal rate over 100) divided by (1 plus inflation rate over 100) minus 1) times 100; general information, not professional advice.
Frequently asked questions
What formula does this use?
real rate = ((1 plus nominal rate over 100) divided by (1 plus inflation rate over 100) minus 1) times 100, the standard form documented by Federal Reserve.
Does the result ever change over time?
No. This is a pure formula with no external rate, so the same inputs always give the same result.
Official sources and verification
- Method: Federal Reserve, checked 2026-06-23.
Reviewed by the CalculatorHub team, edited by James Graham, 2026-06-23. See our methodology. General information, not professional advice.