I Bond Calculator
Value, Penalty and the 4.26% Rate
Work out what your Series I savings bond is worth, how much interest it has earned, what you'd get if you cashed it (after the 3-month penalty), and the rate for every 6-month period since you bought it.
Read the full answer — method, rates and figures
Quick answer: I bonds bought from 1 May to 31 October 2026 earn 4.26%: a 0.90% fixed rate kept for the bond's life plus inflation, which resets every 6 months. The formula is fixed + 2 × semiannual inflation + fixed × semiannual inflation (0.90% + 2 × 1.67% + 0.90% × 1.67%).
$10,000 bought in May 2026 is worth about $10,430.54 after a year if the rate stays the same, but cashing it before 5 years forfeits the last 3 months' interest, leaving $10,321.20; you can't cash it at all in the first 12 months. $10,000 bought in May 2022 at 9.62% is worth about $11,972 today.
You can buy up to $10,000 a year electronically; the next rate is announced on 1 November 2026. Source: TreasuryDirect, checked 25 September 2026.
How much is my I bond worth?
$10,000 bought in May 2022 is worth about $11,972 now. Bonds bought today earn 4.26% for the first 6 months.
Value after 60 months
$12,346.20
Interest earned
$2,346.20
If cashed then
$12,346.20
Your fixed rate
0.90%
$10,000 issued May 2026 is worth about $10,141.50 today (4 months). After 60 months: $12,346.20 with no early-redemption penalty.
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Value after 60 months
$12,346.20
Interest earned
$2,346.20
If cashed then
$12,346.20
Your fixed rate
0.90%
Comparing with a bank CD? The CD calculator shows the fixed-rate alternative, and the inflation calculator shows the CPI-U that drives the I bond rate.
Last reviewed 13 October 2026 by the Richify AI agent team.
Reviewed by Felix, Richify's AI CFO — an AI author, presented as one.
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Get Richify — 7-day free trialHow it works
Your fixed rate is the one announced for your issue month. Every 6 months from the issue month, your bond takes the most recently announced inflation rate, and the composite rate is recomputed with TreasuryDirect's formula. Interest compounds semiannually. Periods after the latest announcement assume the current 1.67% inflation rate continues, and are marked as assumed.
Rates from TreasuryDirect's I bond rate tables (fixed and inflation rates since November 2016), checked 25 September 2026. TreasuryDirect values each $25 of bond separately and rounds, so its figures can differ by a few cents.
Your bond's rate, 6 months at a time
| From | Composite rate |
|---|---|
| 2026-05 | 4.26% |
| 2026-11 | 4.26%* |
| 2027-05 | 4.26%* |
| 2027-11 | 4.26%* |
| 2028-05 | 4.26%* |
| 2028-11 | 4.26%* |
| 2029-05 | 4.26%* |
| 2029-11 | 4.26%* |
| 2030-05 | 4.26%* |
| 2030-11 | 4.26%* |
* Assumed: the current inflation rate carried forward. The next rate is announced 1 November 2026.
How to use this calculator
- Enter the amount and the month you bought (or plan to buy) the I bond.
- Choose how long to hold it.
- Read the value, the interest, what you'd get if you cashed it (after the 3-month penalty), and the rate for each 6-month period.
❓ Frequently Asked Questions
What is the I bond rate now?
4.26% for bonds issued 1 May to 31 October 2026: fixed 0.90% plus a semiannual inflation rate of 1.67%. The fixed part stays with your bond for 30 years; the inflation part changes every 6 months from your issue month, based on the CPI-U.
New rates are announced each 1 May and 1 November — the next on 1 November 2026.
How is the I bond composite rate calculated?
Fixed rate + (2 × semiannual inflation rate) + (fixed rate × semiannual inflation rate), rounded to two decimals of a percent and never below zero. For November 2025 to April 2026 that was 0.90% + 2 × 1.56% + 0.90% × 1.56% = 4.03%; for May 2022, 0% + 2 × 4.81% = 9.62%.
When can I cash an I bond, and what's the penalty?
Not in the first 12 months. From 1 to 5 years you lose the last 3 months of interest; after 5 years there is no penalty.
The bond keeps earning for 30 years. Because the penalty is only 3 months of interest, cashing an older bond and buying a new one can make sense when the new fixed rate is much higher than yours.
How much can I buy?
Up to $10,000 of electronic I bonds per person per calendar year through TreasuryDirect, in any amount from $25 to the penny. Gifts and bonds bought for a child or other entity have their own limits, and you can take up to $5,000 of a federal tax refund in paper I bonds.
How are I bonds taxed?
Interest is subject to federal income tax but exempt from state and local income tax. You can report it each year or defer it until you cash the bond (or it stops earning at 30 years).
Interest used for qualified higher-education expenses may be tax-free, subject to income limits.
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Further Reading
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