U.S. · Savings bonds
I bond rate May 2026: 4.26%.
The fixed, inflation and composite rates for I bonds issued May 1 to October 31, 2026, and what has changed since.
I bonds issued from May 1 to October 31, 2026 earn a composite rate of 4.26% for their first six months: a 0.90% fixed rate that never changes plus a 1.67% six-month inflation rate. Since November 1, 2026 new I bonds carry a 1.40% fixed rate and a 5.51% composite rate. A May 2026 bond moves to 5.00% at its next six-month period.
I bond rate calculator
Result
The May 2026 I bond rate, in full
On May 1, 2026 the Treasury set a fixed rate of 0.90% and a six-month inflation rate of 1.67%. Combining them with the TreasuryDirect formula gives the composite (earnings) rate of 4.26%, a yearly rate that applies to a bond for its first six months. The fixed rate is locked for the life of the bond, up to 30 years. The inflation part is reset every May 1 and November 1 for all I bonds.
Composite = fixed + (2 × inflation) + (fixed × inflation) = 0.0090 + (2 × 0.0167) + (0.0090 × 0.0167) = 0.04255, which rounds to 4.26%.
What the May rate means now
The May 2026 rate was available for I bonds issued from May 1 to October 31, 2026. On November 1, 2026 TreasuryDirect set a new fixed rate of 1.40% and a combined rate of 5.51% for bonds issued from November 1, 2026 to April 30, 2027, so a new purchase no longer gets the May rate. If you bought in May through October 2026 you keep the 0.90% fixed rate for life, and your bond moves to the new inflation rate at its next six-month period.
| Rate set on | Fixed rate (for life) | Six-month inflation rate | Composite rate, first six months |
|---|---|---|---|
| November 1, 2026 | 1.40% | 2.04% | 5.51% |
| May 1, 2026 | 0.90% | 1.67% | 4.26% |
| November 1, 2025 | 0.90% | 1.56% | 4.03% |
| May 1, 2025 | 1.10% | 1.43% | 3.98% |
The composite column is each row's fixed and inflation rate run through the same formula; the November 2026 and May 2026 results match the rates TreasuryDirect shows.
Worked example
$10,000 of I bonds bought in May 2026. For May through October 2026 the bond earns 4.26% a year, about $213 over the six months (10,000 × 4.26% ÷ 2). From the bond's next six-month period (November 2026 for a May purchase) the November 1, 2026 inflation rate of 2.04% applies with the same 0.90% fixed rate: 0.0090 + (2 × 0.0204) + (0.0090 × 0.0204) = 0.04998, or 5.00% a year, about $250 for that period. These are approximations: interest accrues monthly and compounds every six months, so the exact figures are slightly higher after the first period.
Rules that affect what you keep
You can cash in an I bond after 12 months. If you cash in before 5 years, you lose the last 3 months of interest. I bonds are bought electronically in a TreasuryDirect account, and one Social Security number or employer ID may buy up to $10,000 in electronic I bonds per calendar year. I bonds earn interest until you cash them in or they reach 30 years.
Sources
Primary sources opened and checked on November 2, 2026. Figures are as published by the source on that date.
- TreasuryDirect, I bonds interest rates (read November 2, 2026)
- TreasuryDirect, I bonds (read November 2, 2026)
Frequently asked questions
What was the I bond rate in May 2026?
The composite rate for I bonds issued May 1 to October 31, 2026 was 4.26%, made of a 0.90% fixed rate and a 1.67% six-month inflation rate, per TreasuryDirect.
Can I still buy I bonds at the May 2026 rate?
No. The May rate applied to bonds issued through October 31, 2026. Since November 1, 2026, new I bonds carry a 1.40% fixed rate and a 5.51% composite rate for bonds issued through April 30, 2027.
Does the fixed rate on my May 2026 I bond change?
No. The 0.90% fixed rate applies for the life of the bond. Only the inflation part is reset every six months.
How is the I bond composite rate calculated?
Composite rate = fixed rate + (2 × semiannual inflation rate) + (fixed rate × semiannual inflation rate), rounded to the nearest 0.01%.
How much can I buy in a year?
One Social Security number or employer ID may buy up to $10,000 in electronic I bonds in a calendar year, per TreasuryDirect.
Reference data, not investment advice
Rates are copied from TreasuryDirect on the date shown. Interest estimates are approximations. Check TreasuryDirect for the current rate and your own bond's value before you buy or cash in.