Inflation and I Bond

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The I Bond Calculator

Use the I Bond Calculator to get monthly values of your I bond investment. Get a graphical comparison of your I bond's growth to inflation. Download monthly values in CSV format.

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Inflation Calculator

April 10, 2025

Comparing I Bonds to Inflation

If you hold I bonds for five years or more, you'll receive the full interest when you redeem them. As of April 1, 2025, there are 260 I bonds that are older than five years, purchased between September 1998 and April 2020. Out of these, 211 will provide a real return if redeemed in April, meaning their values have increased beyond their inflation-adjusted purchase prices. The remaining 49 have not kept up with inflation, primarily due to the time lag in the inflation adjustment reflecting in the I bond rates. The I bond purchased in May 2000 boasts the highest return at 146.97%, while the February 2015 purchase shows the lowest return at -2.28%.

For I bonds with a fixed rate above zero, a larger percentage of these bonds exceeds inflation-adjusted levels, as illustrated in the graph below.

The chart below illustrates the growth of I bonds purchased monthly from September 1998 to April 2020, compared to inflation during the same period. The variance depicted in the graph represents the difference between the bond value and the inflation-adjusted purchase price as of 4/1/2025, expressed as a percentage of that adjusted price. This reflects the cumulative real growth from the purchase date to 4/1/2025, rather than annual growth.

For instance, as of 4/1/2025, a $10,000 I bond bought in September 1998 had increased by 146% compared to its inflation-adjusted purchase price.

Use the Next and Previous buttons to move around the purchase dates of bonds.

I Bonds 5 Years or Older: Sept 1998 - April 2020

Use the buttons to change dates

I Bonds Over Time

The chart below illustrates the number of I bonds older than five years in relation to their inflation-adjusted purchase prices from January 2020 to April 2025. For instance, in January 2020, there were 196 I bonds over five years old, with 193 surpassing their inflation-adjusted purchase prices and only three falling below that threshold.

In contrast, by April 2025, out of 260 I bonds older than five years, 211 (81%) exceeded their inflation-adjusted purchase prices, while 49 were below.

Click on a legend to toggle a dataset.

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Create a Summary of All Your I Bonds

Use this tool to generate a table summarizing all your I bonds as of the first of the current month. The table will list out the following information:

  • Purchase date
  • Purchase amount
  • Fixed interest
  • Accrued value, and
  • Redemption value.

An additional column will contain a link to the details of the individual I bonds. A copy button makes it easy to copy and paste the generated table into Microsoft Excel or other applications.

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Track I Bond in Quicken and Moneydance
Generate price history files for I bonds. Upload these files to Quicken or Moneydance to track them in these two programs.

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Track All Your I Bonds in Excel
A spreadsheet solution to track all your I bonds and get the accrued value, redemption value, and fixed rate on any date.

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