EE Bond Doubling Calculator
Series EE bonds are guaranteed to double if held 20 years — see the guaranteed value, the implied minimum yield, and what your fixed rate alone would give.
How it works
Fixed value = purchase × (1 + rate ÷ 2)^(years × 2) · Guaranteed value(20 yr) = purchase × 2 · Yield to double = 2^(1/20) − 1
The U.S. Treasury guarantees that a Series EE bond will be worth at least twice its purchase price if held for 20 years, regardless of the low fixed rate printed on it. That guarantee is equivalent to a minimum compound yield of about 3.53% per year — often higher than the stated fixed rate, which is why holding EE bonds exactly to the 20-year mark is the whole point. Cash out early and you only get the modest fixed-rate accrual with no doubling bonus.
Worked example
A $1,000 EE bond with a 2.7% fixed rate would grow to about $1,712 in 20 years on rate alone, but the Treasury tops it up to the guaranteed $2,000. That doubling equals a 3.53% annual yield — noticeably better than 2.7%.
Sources: TreasuryDirect — Series EE bonds
Frequently asked questions
Do all EE bonds double in value?
Yes — EE bonds bought since 2005 are guaranteed to double if held for 20 years. If the fixed rate alone has not doubled the bond by then, the Treasury adds a one-time adjustment to reach exactly double.
What happens if I hold past 20 years?
After the 20-year doubling, the bond keeps earning its fixed rate for another 10 years until it stops earning interest at 30 years. The doubling bonus is only applied once, at year 20.
Why does doubling equal about 3.5%?
Doubling money in 20 years requires a compound rate of 2^(1/20) − 1 ≈ 3.53% per year. That is the effective minimum yield the guarantee locks in.
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Educational estimate, not investment advice. Options and margin involve substantial risk.