I Bond Calculator

Use the calculator below to see how much your I bond may currently be worth, as well as when you may be able to cash it out without incurring penalties.

If you're thinking about buying a new I bond, this tool can only estimate how much you'll earn during the current rate period, since the composite rate changes twice a year. We will update this calculator when the next rate change is announced.

How are I bond rates set, and what could change in November?

An I bond's rate is a combination of a fixed interest rate and a variable inflation rate, together known as a composite rate.

The fixed interest rate remains the same throughout the bond's life, while the inflation rate changes twice a year based on the Consumer Price Index for All Urban Consumers (CPI-U), with the next rate to be announced in November.[1]

Looking historically at past rate changes can help us understand the relationship between inflation and I bonds. In May 2022, when the composite rate hit a staggering 9.62%, the CPI came in at 8.6%, which was the highest 12-month increase since December 1981.

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To understand what the Nov. 1 change may look like, we'll use the formula, which we go over in detail below. But here's a quick overview:

How do I bonds compare with other investments?

I bond yields can seem very attractive. And for many investors looking for income and rates that move in lockstep with inflation, they can be a good option.

"I bonds are a good place to park some cash that you will need in the intermediate term (one to five years). For example, placing cash in I bonds that you will use for a down payment in a couple of years makes a lot of sense," said Kenneth Chavis, a certified financial planner and senior wealth advisor at Versant Capital Management in Phoenix, in an email interview.

But remember that if inflation cools, so too will I bond yields. There are other products that will lock in the higher rates we're seeing today. These include:

Another thing to keep in mind: I bonds may not be as convenient to buy and manage as other securities. While many investors turn to bond exchange-traded funds (ETFs) for quick and easy diversification, I bonds are only bought and sold through the U.S. government via TreasuryDirect, not on secondary markets through brokers.

How much can you make with I bonds?

I bonds are complicated, and even though you earn a guaranteed rate for six months at a time, there's still quite a bit of calculating to arrive at your estimated return.

Let's use an example plugging actual values from previous rate changes.

So why even mention the six-month take? Because your rate is only guaranteed for six months. After that, the rate can go up or down. But just for this example, we'll assume the rate stays the same.

Add the first six months of interest ($199) to your original investment of $10,000 as your new principal. You would earn interest on that new number, or $10,199, for the next six months. That will result in an additional $203 in interest for your second six-month period and a total of about $402 ($199 + $203) in interest total for a one-year period.

At this point, you'd be able to exit the bond agreement. The problem is that if you cash in your bond before you've held it for five years, you lose the last three months of interest you earned.

Interest rates will change over time. If you kept your $10,000 bond for 30 years, you wouldn't lose any interest to penalties, but there is no guarantee your interest rate would stay the same. This can make it difficult to know exactly how much you can make investing in I bonds over a long period — though that is true for most investments.

How I bonds are taxed

Like other investments, the interest you earn from I bonds is subject to taxes. These taxes include federal income tax (but not state or local income tax) and any federal estate, gift, and excise taxes, plus any state-level estate or inheritance taxes[2].

When it comes to reporting your interest, you have two options:

I bond tax benefits

An education tax exclusion can help you exclude all or part of your I bond interest from your gross income if you meet several conditions:

How to buy I bonds

1. Understand how I bonds work

You purchase I bonds electronically by creating an account on the TreasuryDirect website. Paper I bonds used to be purchasable when filing a federal income tax return, but this was discontinued in 2025.

But before you go diving into I bonds, remember:

2. Decide how much you want to invest in I bonds

I bonds have a minimum purchase amount of $25 and a maximum of $10,000 each calendar year. You can buy them in any amount up to $10,000.

3. Figure out how long to keep your I bonds

If you sell an I bond before you've held it for 12 months, you'll receive no interest. If you sell a bond before you've held it for five years, you may lose the last three months' worth of interest. If you hold the bond for five years or more, you won't lose any interest. I bonds can earn interest for 30 years unless you cash them out before then.

Frequently asked questions