About IBondLab

IBondLab is a set of free calculators for U.S. Series I savings bonds — current value, accrued interest, early-redemption penalties and I-bond vs CD/TIPS comparisons. Every tool runs entirely in your browser, so the numbers you type never leave your device.

The math uses the published composite rate (fixed plus twice the semiannual inflation rate) compounded semi-annually. Rates are stored as constants, so the site stays correct without updates.

IBondLab is maintained by an independent maker. It may show non-intrusive advertising once traffic justifies it. We do not collect or sell your data.