I bonds interest rates â TreasuryDirect
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An example

The composite rate for I bonds issued from May 2024 through October 2024 is 4.28%.

Here's how we got that rate:

Fixed rate 1.30% Semiannual (1/2 year) inflation rate 1.48% Composite rate formula: [Fixed rate + (2 x semiannual inflation rate) + (fixed rate x semiannual inflation rate)] [0.0130 + (2 x 0.0148) + (0.0130 x 0.0148)] Gives a composite rate of [0.0130 + 0.0296 + 0.0001924] Adding the parts gives 0.0427924 Rounding gives 0.0428 Turning the decimal number to a percentage gives a composite rate of 4.28%

Interest rate changes depend on when we issued the bond

Although we announce the new rates in May and November, the date when the rate changes for your bond is every 6 months from the issue date of your bond. Use this table to understand when each new rate begins to apply to your I bond.

If we issued your bond in Your interest rate changes every January July 1 and January 1 February August 1 and February 1 March September 1 and March 1 April October 1 and April 1 May November 1 and May 1 June December 1 and June 1 July January 1 and July 1 August February 1 and August 1 September March 1 and September 1 October April 1 and October 1 November May 1 and November 1 December June 1 and December 1

The interest gets added to the bond's value

I bonds earn interest from the first day of the month you buy them.

Twice a year, we add all the interest the bond earned in the previous 6 months to the main (principal) value of the bond.

That gives the bond a new value (old value + interest earned).

Over the next 6 months, we apply the new interest rate to that entire new value.

This is called semiannually compounding (adding value 2 times a year). That way, your money grows not just from the interest percentage but from the fact that the interest is calculated on a growing balance.

How do you find the current value of an I bond? If the bond is in TreasuryDirect, look in your account there. If the bond is paper, use the Savings Bond Calculator.

Note: For bonds less than 5 years old, values shown in TreasuryDirect and the Calculator donât include the last 3 months of interest. Thatâs because if you cash a bond before 5 years, we donât pay you the final 3 months of interest.

What have interest rates been for I bonds?

We've put all the rates together in one chart â fixed rate, inflation rate, and combined rate. You can look up a specific bond there and see its entire history. You will probably have to enlarge the chart to view a particular row. We also have a Series I Bond rate history chart.

Below, we show you historical rates in separate tables.

Fixed rates

The fixed rate that we set each May and November applies to all bonds we issue in the 6 months following the date when we set the rate. The fixed rate applies for the life of the bond.

Inflation rates

The inflation rate that we set each May and November applies for 6 months to all I bonds that we ever issued.

Current composite rates

The table below shows the current composite rate for all I bonds. Each composite rate is a yearly rate that applies for 6 months.