Series I Bond Calculator

Series I bonds (sold since September 1998) are bought at face value and grow with a composite rate: a fixed rate set for the bond's life plus an inflation adjustment that resets every May and November. That makes their value path hard to compute by hand — the Treasury's published tables are the only authoritative source, and that's what the calculator reads.

How I bond values move

• Rates reset semiannually: your bond's rate changes on its own 6-month anniversary schedule, not on the calendar reset — a common source of confusion the tables resolve exactly.
• 3-month penalty under 5 years: values shown for bonds younger than 5 years already exclude the last 3 months of interest, exactly what your bank would pay today.
• 12-month lockup: I bonds can't be cashed at all in the first year (the calculator will tell you when yours becomes redeemable).
• 30-year life: after final maturity the bond stops earning — the 2028-2029 wave of maturing 1998-99 I bonds is coming.

Paper I bonds from tax refunds

Millions of paper I bonds were issued through the IRS tax-refund program (2010–2024, denominations $50 to $5,000). They work the same as any I bond — pick "Series I", the printed denomination and the issue date, and you'll get the exact redemption value. Keep the whole stack organized in the private inventory.

High-inflation vintages are worth checking

I bonds bought in 2021–2022 rode record 7.12% and 9.62% inflation rates; many holders don't realize how much they've grown — or that rates have since fallen, which changes the hold-or-cash math. See today's exact value first, then decide.

→ Check your bond's value now (free)