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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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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Compare I Bond to Bond Funds

Compare I Bond to

  • VUSTX
  • VBMFX
  • VFISX
  • VSGBX
  • VFITX

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September 13, 2023

Comparing I Bonds to Inflation

If you hold I bonds for five years or longer you will get the full interest when you redeem them. As of September 1, 2023, there are 240 I bonds that are older than five years. These are the I bonds purchased from September 1998 through August 2018, the five year mark as of September 2023. Of these 240 I bonds, 164 will provide a real return if you redeem them in August. In other words, 164 of these I bonds have grown in their values to exceed their inflation-adjusted purchase prices and the remaining 76 are lagging behind inflation.

For I bonds with fixed rate greater than zero, a higher percentage of the bonds is above inflation-adjusted levels, as shown in the graph below.

For I bonds purchased each month starting from September 1998 through August 2018, the chart below shows how much the bonds had grown in values compared to the growth in inflation for the same period. The variance shown in the graph is the difference between the bond value and the inflation-adjusted purchase price on 9/1/2023 as a percentage of the inflation-adjusted purchase price. So it is the cumulative real growth from the purchase date through 9/1/2023 (not annual growth). As an example, as on 9/1/2023, a $10,000 I bond purchased in September 1998 had grown 130.15% over 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 - August 2018

Use the buttons to change dates

I Bonds Over Time

The chart below shows the number of I bonds older than five years above and below their inflation-adjusted purchase prices for each month from January 2020 through September 2023. For example, in January 2020, there were 196 I bonds older than 5 years. Out of them, 193 had grown in their values to exceed their respective purchase prices adjusted for inflation, and only three were below those levels. On the other hand, in September 2023, 164 out of a total of 240 I bonds (68%) older than five years were above and 76 were below their inflation-adjusted purchase prices.

Click on a legend to toggle a dataset.

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