I Bond Yield Calculator 2026
Calculate your I Bond composite rate, monthly interest earned, and see how your yield resets semi-annually. Based on the Nov 2025 fixed rate of 1.30% from TreasuryDirect.gov.
How I Bond Composite Rate Works
Series I Savings Bonds earn interest based on a composite rate combining two components: a fixed rate and a semiannual inflation rate tied to the Consumer Price Index (CPI-U). The formula is: Composite = fixed + (2 × semiannual CPI) + (fixed × semiannual CPI). The fixed rate is set at purchase and never changes for the life of the bond. The inflation component resets every six months — in May and November — based on CPI-U data reported by the Bureau of Labor Statistics.
Bonds purchased from November 2025 through April 2026 carry a fixed rate of 1.30%, the highest fixed rate since 2007. This locks in a real return above inflation for the entire holding period, regardless of future CPI resets. Source: TreasuryDirect.gov. Last updated: May 2026.
I Bond Rate Reset Schedule
| Purchase Month | Reset Months | First Reset |
|---|---|---|
| January | January / July | July (6 months later) |
| February | February / August | August |
| March | March / September | September |
| November–April (2025–26) | Varies by month | Fixed at 1.30% for life |
I Bonds vs HYSA vs Treasury Bills 2026
As of May 2026, high-yield savings accounts offer around 4.5–5.0% APY, while 6-month Treasury Bills yield approximately 4.2–4.6%. I Bonds with the 1.30% fixed rate plus current CPI inflation offer roughly 4.28% composite. The key advantage of I Bonds is that the fixed component persists for 30 years — if inflation rises again, your yield automatically rises too, unlike a locked CD or T-Bill. The trade-off: 12-month lockup (no redemption in year one) and a 3-month interest penalty if redeemed before 5 years. For funds you won't need for at least 5 years, I Bonds with a high fixed rate are a compelling inflation hedge.