Savings Bond Calculator (I Bond & Series EE Bond)
Free savings bond calculator for U.S. Series I and Series EE bonds. Enter your purchase amount and rate to project the accrued value, redemption value, and early-redemption penalty over time.
What Is a Savings Bond Calculator?
U.S. savings bonds are low-risk securities issued directly by the Treasury to individual savers rather than traded on a market. Series I bonds combine a fixed rate that never changes with a semiannual inflation rate that resets twice a year, so their return keeps pace with inflation. Series EE bonds pay a single fixed rate instead, but carry a distinctive guarantee: Treasury promises to make an EE bond worth exactly double its purchase price by its 20-year anniversary, topping up the balance with a one-time adjustment if accumulated interest alone would fall short.
This calculator projects the accrued value and redemption value of either series over a chosen holding period, and applies the two rules that catch most first-time buyers off guard: bonds cannot be cashed in the first 12 months at all, and cashing in before 5 years forfeits the most recent 3 months of interest. Because real I bond rates change every six months, treat the projection here as an illustration of the mechanics rather than an exact prediction of a specific bond's future value.
How to Use This Savings Bond Calculator
- Choose the bond series Pick Series I for an inflation-adjusted bond, or Series EE for a fixed-rate bond with the 20-year doubling guarantee.
- Enter the purchase amount The amount you paid (or plan to pay) for the electronic bond.
- Enter the fixed rate The rate announced by Treasury when the bond was issued -- this stays fixed for the bond's entire life.
- For I bonds, enter the semiannual inflation rate The current inflation-linked component, which this calculator assumes stays constant across future 6-month periods.
- Set the holding period Choose how many years you plan to hold the bond, from 1 to 30, and read off the accrued value, redemption value, and milestone table below.
Tips for getting more out of it
- If you plan to redeem within 5 years, check the accrued value at both your target date and 3 months earlier -- the difference is exactly what the early-redemption penalty will cost you.
- Because I bond rates reset every 6 months, a bond bought years ago is likely earning a different composite rate today than this calculator's single-rate assumption would suggest -- use TreasuryDirect's own calculator for an existing bond's exact current value.
- Series EE bonds are the more predictable of the two series if you specifically want the year-20 doubling guarantee; I bonds are the better inflation hedge if your priority is keeping pace with rising prices.
- Electronic I bonds and EE bonds bought through TreasuryDirect can be purchased in any amount to the cent, with a $25 minimum -- there is no need to buy in round $50 or $100 increments as older paper bonds required.
- Both series stop earning any interest after 30 years, so a bond left forgotten past its final maturity is quietly losing purchasing power to inflation with no offsetting return.
When to Use This Calculator
Deciding when a bond clears the 5-year penalty window
Compare the accrued value against the redemption value at different holding periods to see exactly how much the 3-month interest forfeiture costs if you cash out early.
Projecting an I bond's growth under today's rate
Estimate how a new I bond purchase might grow if the current composite rate held steady, while remembering the rate itself resets every 6 months.
Checking whether an EE bond is on track to double
See how much of the 20-year doubling comes from ordinary compounding versus the one-time top-up Treasury applies if interest alone would not be enough.
Comparing I bonds and EE bonds side by side
Switch between the two series with the same purchase amount to see how an inflation-linked bond and a fixed-rate, doubling-guaranteed bond diverge over a long holding period.
Savings Bond Glossary
- Composite rate
- The I bond's actual annual rate: fixed rate + (2 x semiannual inflation rate) + (fixed rate x semiannual inflation rate). It is guaranteed never to fall below 0%.
- Fixed rate
- The rate set by Treasury when a bond is issued. It never changes for that bond's life -- for I bonds it is one input into the composite rate, and for EE bonds it is the only rate.
- Semiannual inflation rate
- The inflation-linked component of an I bond's composite rate, based on CPI-U data and reset every May 1 and November 1.
- Par value
- The original purchase amount. An I bond or EE bond is guaranteed never to be redeemed for less than par, even after an early-redemption penalty.
- Early-redemption penalty
- Cashing in a savings bond less than 5 years after purchase forfeits the most recent 3 months of interest. Bonds cannot be redeemed at all in the first 12 months.
- 20-year doubling guarantee
- Treasury's promise that a Series EE bond will be worth at least double its purchase price by its 20-year anniversary, with a one-time balance adjustment if needed to reach that value.
- TreasuryDirect
- The U.S. Treasury's official website for buying, holding, and redeeming electronic savings bonds directly from the government.
Savings Bond Calculator FAQ
Side Note -- Why Savings Bonds Feel Different from Every Other Investment
Series EE bonds have existed in something close to their current form since 1980, but their defining feature -- the promise to double in value by year 20 -- has meant very different things depending on when a bond was bought. In the early 1980s, fixed rates were high enough that ordinary compounding alone could double a bond well before the 20-year mark. By the 2000s and 2010s, as fixed rates fell toward zero, most EE bonds needed a Treasury top-up adjustment at the 20-year anniversary just to reach double face value, turning what looked like a modest fixed-rate bond into an effective yield that quietly beat the stated rate for anyone who held it the full term.
I bonds, by contrast, are a much newer invention, first issued in 1998 specifically to give individual savers an inflation hedge that did not require buying and tracking Treasury Inflation-Protected Securities (TIPS) through a brokerage account. Because the inflation-linked half of an I bond's rate is published twice a year using the same Consumer Price Index data that drives Social Security cost-of-living adjustments, I bond rates became an unusually visible bellwether during periods of high inflation, with some announcement dates drawing more everyday attention than most bond-market news ever gets.
One quirk that trips up plenty of savers: the interest a savings bond earns is exempt from state and local income tax everywhere in the U.S., and federal tax on that interest can be deferred all the way until the bond is redeemed or reaches final maturity at 30 years -- whichever comes first. Held long enough and used for qualifying higher-education expenses, I bond interest can even be excluded from federal tax entirely under the Education Savings Bond Program, a benefit that is easy to miss because it is buried in tax-filing instructions rather than advertised on the bond itself.