USAUS Treasury Series I Savings BondFinance & SalaryUS Treasury Series I Savings Bond Composite Rate & Interest Calculator
Calculate your semiannual and annual interest yield on US Treasury Series I Savings Bonds using the Treasury composite formula combining fixed rate and semiannual inflation rate (CPI-U).
Calculator Inputs
Live Real-TimeTotal Annualized I-Bond Composite Rate (%)
Annual Guaranteed Interest Earned ($/yr)
502 %
3-Month Interest Penalty (if redeemed before 5 years)
125.5 %
Detailed Calculation Breakdown
Calculation Methodology
Composite Rate = Fixed Rate + (2 * Semiannual Inflation Rate) + (Fixed Rate * Semiannual Inflation Rate). Annual Interest = Principal * (Composite Rate% / 100).
Important Legal & Educational Disclaimer
I-Bonds must be held for a minimum of 1 year. If redeemed before 5 years, you forfeit the previous 3 months of interest. Annual purchase limit is $10,000 per SSN per calendar year.
This calculator is designed for educational and informational purposes only based on public statutory frameworks. The outputs do not constitute binding financial, tax, or legal advice. We assume no liability for decisions made based on these estimations. Always verify with the relevant official authorities or a certified professional advisor.
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