Calculate real price from nominal price and price index, convert amounts between periods with matching indexes, and find their total inflation rate. Historical CPI-U presets use U.S. annual averages (1982–84 = 100), ending in 2023; the corrected 2023 value is 304.702.

Use indexes from the same series and reference base. Presets are historical U.S. CPI-U annual averages, all items, not seasonally adjusted (1982–84 = 100); they end in 2023.

Historical CPI preset

Real Price Formula

The following formula is used to calculate the Real Price. 

RP = NP / PI × 100
  • Where RP is the Real Price ($)
  • NP is the nominal price ($) 
  • PI is the price index with reference base = 100; for a base-1 index, omit the ×100 factor.

To calculate real price with a base-100 index, divide nominal price by the index and multiply by 100. Use indexes from the same series and reference base for period conversions.

How to Calculate Real Price?

The following example problems outline how to calculate Real Price.

Example Problem #1:

  1. First, determine the nominal price ($).
    1. The nominal price ($) is given as 100.
  2. Next, determine the price index.
    1. The price index is provided as 30.
  3. Finally, calculate the Real Price using the equation above: 

RP = NP / PI * 100

The values given above are inserted into the equation below:

RP = 100 / 30 * 100 = 333.33 ($)

Example Problem #2: 

For this problem, the variables needed are provided below:

nominal price ($) = 400

price index = 20

This example problem is a test of your knowledge on the subject. Use the calculator above to check your answer. 

RP = NP / PI * 100 = ?