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Savings Bond Calculator (US I Bonds)

Estimate the value of a US Series I savings bond using the composite rate formula.

Also try:🏦 High-Yield Savings Account 💳 CD Interest Rate 💹 Compound Interest

💱 Amounts shown in selected currency. Rates are approximate — for exact rates check your bank.

About This Calculator

Series I savings bonds earn a composite rate combining a fixed rate and a semi-annual inflation rate, compounded every six months. Enter your bond details to estimate its value.

About This Calculator

Series I savings bonds earn a composite rate combining a fixed rate and a semi-annual inflation rate, compounded every six months. Enter your bond details to estimate its value.

Frequently Asked Questions

How is the I bond composite rate calculated?

Composite Rate = Fixed Rate + (2 × Semi-Annual Inflation Rate) + (Fixed Rate × Semi-Annual Inflation Rate), compounded every 6 months.

How long do I bonds earn interest?

I bonds earn interest for up to 30 years, but you must hold them at least 1 year, and you forfeit the last 3 months of interest if cashed before 5 years.