Savings Bond Calculator

Quick Answer

Last updated: 10 November 2026 ·How we calculate this: TreasuryDirect rules for Series EE and I savings bonds

How This Savings Bond Calculator Works

Choose EE or I bond, enter what you paid and how long you will hold the bond, and the rate. For EE bonds, enter the fixed rate set when you bought the bond. For I bonds, enter the fixed rate and the semiannual inflation rate; the calculator combines them with the Treasury’s composite rate formula. It grows the bond every 6 months, applies the 3-month penalty if you cash in before 5 years, and adds the 20-year doubling guarantee for EE bonds.

How to Use the Savings Bond Calculator

1. Choose Series EE or Series I.
2. Enter the amount you paid and how long you will hold the bond.
3. Enter the EE fixed rate, or the I bond fixed and semiannual inflation rates.
4. Press Calculate.
5. Read the estimated value, the interest, and any penalty or doubling.

Savings Bond Formulas

• Growth: value = amount × (1 + rate ÷ 2)^(number of 6-month periods)
• I bond composite rate: fixed rate + (2 × semiannual inflation rate) + (fixed rate × semiannual inflation rate)
• EE guarantee: at 20 years the value is at least 2 × the amount paid
• Early cash-in: before 5 years, you get the value from 3 months earlier

Key Terms

• Series EE bond: a savings bond with a fixed rate and a 20-year doubling guarantee.
• Series I bond: a savings bond whose rate combines a fixed rate and inflation.
• Composite rate: the combined I bond rate from the fixed and inflation rates.
• Semiannual compounding: interest added to principal every 6 months.
• Redeem: to cash in a savings bond.

Worked Example

You buy $5,000 of I bonds in November 2026 and cash them in after 3 years. Assume the rate stays at 5.51%.

• Composite rate = 1.40% + 2 × 2.04% + 1.40% × 2.04% = 5.51%
• You held them less than 5 years, so the last 3 months of interest are lost: interest is counted for 33 months.
• Estimated value = $5,806.66
• Interest earned = $806.66, all subject to federal income tax but not state tax.

Real-Life Examples

• EE for 20 years: $10,000 at 2.90% would grow to $17,786 on its own, so the Treasury tops it up to $20,000.
• EE for 10 years: $1,000 at 2.90% is worth about $1,333.65.
• I bond for 3 years: $5,000 at 5.51% is worth about $5,806.66 after the 3-month penalty.
• Holding to 5 years: waiting until 60 months removes the penalty.

Savings Bonds vs CDs

• Savings bonds: backed by the US government, exempt from state and local income tax, and federal tax can be deferred until you cash in.
• CDs: fixed terms at banks, FDIC insured up to the limit, interest taxed each year at federal and state level.
• Access: bonds are locked for 12 months; CDs charge an early withdrawal penalty.

EE Bond Value Over Time

EE or I Bond?

An EE bond’s fixed rate is often lower than the I bond rate, but the doubling guarantee means an EE bond held exactly 20 years earns the equivalent of about 3.5% a year. If you will hold for 20 years, EE bonds can beat a low fixed rate; if you might cash in sooner, the guarantee does not help. I bonds protect your savings against inflation, so they suit money you want to keep its buying power.

Common Mistakes to Avoid

• Cashing in before 5 years without thinking. You lose 3 months of interest.
• Selling an EE bond just before 20 years. You miss the doubling top-up.
• Assuming I bond rates stay the same. The inflation part changes every 6 months.
• Using this for old paper bonds. Older bonds follow different rules; use TreasuryDirect’s tool.
• Forgetting tax. Interest is federally taxable when you cash in.

Frequently Asked Questions

References & Sources