Calculate the monthly values of your I bond investment. Get a graphical view comparing the growth of your I bond to the increase in inflation.
You can also download the monthly values as a CSV file by pressing the Download CSV button on the next page.
ibdate is the date of purchase in YYYY-MM format and the value after
ibval is the amount without the dollar sign. In the second example we are linking an I bond for $7,534.59 purchased in July 2000.
The composite rate will never be less than zero. The interest income is computed by applying the composite rate based on the interest computation methodology.
Composite rate = [fixed rate + (2 x semiannual inflation rate) + (fixed rate x semiannual inflation rate)]
Inflation-adjusted value = (Purchase value of bond/base CPI-U index) X CPI-U index for the month