About
About ibondrate
A free, open calculator that turns one I bond issue date into a clear redemption-timing plan.
US Series I savings bonds have rules that make timing matter: a 12-month lock, a 3-month interest penalty before 5 years, and a rate that resets every 6 months on the bond's anniversary. ibondrate does the arithmetic for your specific bond.
It uses the U.S. Treasury fixed-rate and semiannual-inflation tables (cross-checked against TreasuryDirect announcements) and the published composite-rate formula, then shows the current and next rate, an estimated value, the 3-month penalty, every key date, and the best month to redeem so the penalty falls on the lowest-rate months. It is a static page, so your inputs stay in your browser. Not affiliated with the U.S. Treasury or TreasuryDirect; informational only, not financial advice.