I Bond Calculator
How much is my I bond worth? Choose the month you bought it and the amount, and see its current value, the interest it has earned, whether the 3-month penalty applies, and the rate for every six-month period. The calculator uses Treasury’s official rates from September 1998 to date. Its $25 values match Treasury’s published value files to the cent, and larger amounts follow Treasury’s own scaling rules (31 CFR 359.19 and 359.55).
Maintained by Archie Chang · Rates and values checked against Treasury October 23, 2026 · Methodology & sources
Your I bond
Value as of (default is this month)
Values run through November 2026, the last month that needs only announced rates. Later months depend on future announcements, so they are not shown.
What your I bond is worth
Value on the first of October 2026 (after the 3-month interest penalty)
$11,904.00
$10,000.00 invested, $1,904.00 of interest counted
- Fixed rate of this bond (never changes)
- 0.00%
- Composite rate of the rate period that contains this month
- 3.34%
- 3-month interest penalty
- Applies: $100.00 of interest not counted
- Until the penalty ends (5 years)
- 7 months
- Value without the penalty
- $12,004.00
Electronic values follow 31 CFR 359.55: your amount ÷ 100 × the value of a $100 bond (4 × the $25 value), rounded to the cent.
Rate periods and value for your bond
| Period | Composite rate | Value at start of period |
|---|---|---|
| May 2022 to October 2022 | 9.62% | $10,000.00 |
| November 2022 to April 2023 | 6.48% | $10,480.00 |
| May 2023 to October 2023 | 3.38% | $10,820.00 |
| November 2023 to April 2024 | 3.94% | $11,004.00 |
| May 2024 to October 2024 | 2.96% | $11,220.00 |
| November 2024 to April 2025 | 1.90% | $11,388.00 |
| May 2025 to October 2025 | 2.86% | $11,496.00 |
| November 2025 to April 2026 | 3.12% | $11,660.00 |
| May 2026 to October 2026 (in progress) | 3.34% | $11,840.00 |
Interest is added to the value every month and compounds twice a year, at each six-month mark. The value at the start of a period is before any 3-month penalty.
How an I bond’s value grows
An I bond is bought at face value and earns interest from the first day of the issue month. Its rate has two parts: a fixed rate set when you buy, which never changes, and an inflation rate that resets every six months. Together they make the composite rate. The rate period is six months long and starts on the issue month of your bond and every six months after it. Interest is added every month and compounded twice a year.
Example from Treasury’s tables: a $1,000 paper I bond bought in May 2022 (0.00% fixed) is worth $1,064.80 in May 2023. The first six months earned 9.62% a year, and the second period earned 6.48%, but because the bond is less than five years old the last three months of interest are left out of that value. Our calculator returns exactly $1,064.80 for it.
The current rate is 4.26% and the November 2026 change is on the I bond rate page. To compare with a bank product, try the CD rate calculator. For Series EE bonds, use the savings bond calculator.
The 3-month interest penalty
Cash an I bond less than five years after the issue date and Treasury gives you the value from three months earlier. The calculator shows that amount as your value and tells you how much interest was left out. Once the bond reaches five years the penalty disappears and the full value counts. A bond cannot be cashed during its first year, and the value is never lower than what you paid. Treasury’s published value tables already include the penalty (31 CFR 359.40(b)).
How accurate is this calculator?
We compared our method with every value in Treasury’s Savings Bond Value Files for a $25 Series I bond, from September 1998 to November 2026: 57,608 values for bonds issued in every month, including bonds in their first year (no value), under five years old (penalty), through the 0% rate periods of 2009 and 2015, and the high-rate bonds of 2022. All of them match to the cent. Treasury’s paper tables for bigger denominations are the $25 value times the denomination divided by 25 (287,541 values checked), and the calculator does the same for paper bonds. Electronic bonds use the same $25 value under 31 CFR 359.55. Values stop at November 2026 because later months depend on rates Treasury sets in future announcements.
I bond value questions
How much is my I bond worth?
Pick the month and year you bought it, enter the amount, and the calculator gives its value for any month through November 2026. It applies your bond’s own fixed rate, the composite rate for each six-month period, monthly interest and semiannual compounding. For a bond under five years old the value excludes the last three months of interest, as Treasury’s published value tables do (31 CFR 359.40(b)).
How does the 3-month interest penalty work?
If you cash an I bond before it is five years old, Treasury takes away the last three months of interest (31 CFR 359.7): the value is calculated as if you redeemed three months earlier, and never below what you paid. After five years there is no penalty. The redemption values Treasury publishes already include the penalty (31 CFR 359.40(b)).
When can I cash an I bond?
Not in the first 12 months after the issue month (6 months for bonds issued before February 2003). After that you can cash the bond. Before five years you lose the last three months of interest, and the bond stops earning interest after 30 years.
How is the value of an I bond calculated?
Interest accrues from the first day of the issue month at the composite rate: fixed rate + 2 × six-month inflation rate + fixed × inflation rate. The rate is reset every six months from your issue month. Within a period the value grows by (1 + rate ÷ 2) to the power of months ÷ 6, rounded to the cent, and at the end of each six-month period the interest is compounded into the value. Treasury calculates all interest on a $25 unit and scales it to larger amounts (31 CFR 359.19).
How are electronic I bond values calculated?
31 CFR 359.55 values a book-entry (electronic) bond as the amount you paid ÷ 100 × the current redemption value of a $100 bond, rounded to the nearest cent, and 31 CFR 359.19 bases every calculation on a $25 unit, so the $100 value is 4 × the $25 value. Example: a $10,000 electronic bond bought in May 2022 is worth $11,904.00 in October 2026, which is the official $25 value of $29.76 × 400. Paper bonds work the same way: the $25 value × the denomination ÷ 25. The calculator shows the value on the first of the month, and Treasury’s own tools may use the exact day.
What fixed rate did my I bond get?
Treasury set it in May or November of the year you bought and it never changes. The calculator shows it for your issue month. For example, bonds issued from November 2025 to October 2026 have a fixed rate of 0.90%, and bonds from May 2022 to October 2022 have 0.00%.
Is I bond interest taxable?
I bond interest is subject to federal income tax and exempt from state and local income tax. You can report it every year or wait until you cash the bond or it matures after 30 years. This calculator does not include taxes. Check TreasuryDirect’s tax information and a tax professional for your situation.
What is the current I bond interest rate?
For bonds issued May 1 to October 31, 2026 the composite rate is 4.26% (0.90% fixed). The new inflation rate from November 1, 2026 computes to 2.04% for six months, and the new fixed rate is not announced yet. See the I bond rate page for the full history.
Sources (checked October 23, 2026): Treasury Savings Bond Value Files · TreasuryDirect Savings Bond Calculator · 31 CFR Part 359 · TreasuryDirect: I bond interest rates · Treasury rate chart (PDF)