I bond value calculator
To estimate what a Series I savings bond is worth today, enter the amount you paid and the bond’s issue period below. The calculator compounds each six-month interest window at the composite rate in effect, applies the rule that I bonds cannot be redeemed in the first 12 months, and subtracts the 3-months-interest penalty if you have held it less than five years. This is an estimate — for the exact penny value, use TreasuryDirect’s official Savings Bond Calculator.
Data as of May 2026.
How the estimate works
The calculator models the official accrual rules for Series I bonds:
- Monthly accrual, semiannual compounding. Interest is added every month and compounds every 6 months. We compound each of the bond’s own six-month windows at the composite rate that applied to it.
- 12-month lock-up. An I bond cannot be cashed in its first year, so values inside that window are shown as accrued value, not a redemption amount.
- 3-month penalty under 5 years. If you redeem before 5 years, you forfeit the most recent 3 months of interest.
- 0% floor. The composite rate is never below 0%, so an I bond never loses nominal value.
This is a transparent approximation, not the official figure. See the methodology for the exact formula and its limits, and the how interest accrues guide.
Frequently asked questions
How do I find out what my I bond is worth?
Enter your purchase amount and the bond's issue period above for an estimate. The calculator compounds each of the bond's six-month windows at the composite rate Treasury had in effect, then subtracts the 3-month penalty if you have held it less than five years. For the exact penny value, use TreasuryDirect's official Savings Bond Calculator.
Why does my I bond value differ from TreasuryDirect's?
This is a transparent estimate. Treasury computes value per $25 of face value using exact monthly accrual factors and rounds to the cent; this tool compounds semiannually and approximates the final partial window. Differences are usually a few cents to a couple of dollars. Treat TreasuryDirect's figure as authoritative.
Can I cash my I bond at any time?
No. You cannot redeem an I bond in the first 12 months. From 12 months to 5 years you can redeem but forfeit the last 3 months of interest. After 5 years there is no penalty. I bonds stop earning interest after 30 years.
Related
- Composite-rate calculator · EE doubling calculator
- The 3-month early-redemption penalty · I bond rates by period
Not investment or tax advice. BondValue is an independent reference, not affiliated with the U.S. Treasury or TreasuryDirect. Savings bond rates reset every 6 months (on May 1 and November 1), and any value shown here is an estimate. Verify current rates and the exact penny value of your bonds at TreasuryDirect’s official Savings Bond Calculator. Consult a qualified professional before making financial decisions.
Last updated: 2026-06-21