I-Bond Composite Rate

I-Bond value calculator

Estimate what a Series I bond is worth over time at the current rate.

How the I-Bond rate works

A Series I savings bond earns a composite rate that combines afixed rate (set for the life of the bond at purchase) and asemiannual inflation rate (reset twice a year based on CPI). The U.S. Treasury publishes new rates on May 1 and November 1. The composite formula is:

composite = fixed + (2 × semiannual inflation) + (fixed × semiannual inflation)

Interest is added monthly and compounds semiannually. You must hold an I-Bond for at least1 year. If you redeem before 5 years, you forfeit the most recent3 months of interest. Figures here are estimates that assume the current rate persists; the actual rate your bond earns resets every six months.