Real Interest Rate Calculator

Use our free real interest rate calculator to find the real interest rate — the nominal rate adjusted for inflation. Both the simple approximation (r ≈ i - π) and the exact Fisher equation calculation are provided.

Financial

Nominal Interest Rate (%)

Inflation Rate (%)

Principal Amount (optional)

Time Period (years, optional)

years

Currency

Formula

The real interest rate is the nominal interest rate adjusted for inflation. It represents the true cost of borrowing or the real return on savings. A positive real rate means your money grows in purchasing power.

r_real = (1 + r_nominal) / (1 + π) - 1 (approx: r ≈ i - π)

Percentage: The percentage value you want to apply

Number: The original number or value

Result: The calculated result

How It Works

1Enter the nominal (stated) interest rate.
2Enter the inflation rate.
3Optionally enter a principal amount and time period.
4The calculator shows both the approximate (r ≈ i - π) and exact Fisher equation results.

Examples

6% nominal rate with 2.5% inflation

1.Approximate: 6% - 2.5% = 3.50%
2.Exact Fisher: (1.06/1.025) - 1 = 3.41%

Result: 3.41%

Frequently Asked Questions

The real interest rate is the nominal interest rate adjusted for inflation. It shows the true cost of borrowing or true return on savings in terms of purchasing power.

The simple approximation (r ≈ i - π) works well for low rates. The Fisher equation is more precise for higher rates or when accuracy matters.

A negative real rate means inflation is higher than the nominal rate, so your purchasing power is declining despite earning interest.

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Real vs Nominal Interest Rates

CalculateMe Team

Last updated: 2026-07-15

Frequently Asked Questions

The real interest rate is the nominal interest rate adjusted for inflation. It shows the true cost of borrowing or true return on savings in terms of purchasing power.

The simple approximation (r ≈ i - π) works well for low rates. The Fisher equation is more precise for higher rates or when accuracy matters.

A negative real rate means inflation is higher than the nominal rate, so your purchasing power is declining despite earning interest.

Real Interest Rate Calculator

Formula

How It Works

Examples

6% nominal rate with 2.5% inflation

Frequently Asked Questions

What is the real interest rate?

Why are there two calculations?

What does a negative real rate mean?

Related Calculators

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Real Interest Rate Calculator

Formula

How It Works

Examples

6% nominal rate with 2.5% inflation

Frequently Asked Questions

What is the real interest rate?

Why are there two calculations?

What does a negative real rate mean?

Related Calculators

Related Articles