Series I Savings Bonds, or I Bonds for short, earn interest which is credited to their value each month. The interest rate changes every six months to compensate for inflation. There are calculators that will apply the different rates to determine how much an I Bond is worth at any point in time. (See the Links page.) But these calculators are like a 'black box'. They show the result, but not how it is arrived at. Also, for I Bonds held less than 5 years they omit the last three months interest, because it would be forfeit if the owner redeems.

The purpose of this web site is to show the complete history of interest earned and the resulting value for any I Bond. This way you can see how the current value is arrived at and not just accept the results of a 'black box'. Also, no deduction is made for any early withdrawl penalty. If an owner wants to redeem his bonds before five years, he just needs to look at their value 3 months earlier.

Home Page

This page has links to pages for every I Bond issued. Click [$25], [$50], [$75], [$100], [$200], [$500], [$1,000], [$5,000], or [$10,000] to choose which denomination of I Bond to display. All $50 and larger denominations and are multiples of the $25 bond's value. For example, if the value of a $25 bond is $25.58, then the value of a $5,000 bond will be exactly 200 times as much, or $5,116.00.

Growth in Value of One I Bond

This page shows the growth in value for an I Bond purchased at any time during the indicated month. Interest is earned for an entire month even if the purchase is made on the month's last day; and it is credited the first day of the following month. I Bonds can't be redeemed before one year; and if held less than five years, the last three month's interest is forfeit. Therefore, if redeemed between one and five years, you will receive the value shown for three months before redemption.

Separate Windows

It's intended that when you click the link for a month on the home page, the page for that month will open in a separate window. This way you can more easily view multiple months, one after the other. This works with most browsers including Internet Explorer and Safari. However, if you prefer to use only one window, close the original home page window after the second window opens, and then just use the remaining window.


You should be able to copy and paste rows from one of the bond tables into a spreadsheet for further manipulation. My Excel version 2003 – does a fair job of pasting each table element into the appropriate cells. Here's how I do it:

  1. To select the cells to copy click just to the left of the 'J' in Jan. Hold down the shift key and click just to the right of the last number in the bottom row.
  2. After Copying, select the top left cell in a blank Excel worksheet and Paste.
  3. If the headings are off by one column, select the cells making up the Jan heading and choose Insert / Cells / Shift Cells Right.

Errors and Comments

I welcome comments about errors, suggested improvements, or just general impressions. Please email me at