Savings Bond Calculator
Enter your Series EE bond's purchase price, its fixed annual rate, the purchase date, and the date to value it as of. The calculator compounds the rate semiannually and applies the Treasury's 20-year doubling guarantee to estimate the current redemption value.
How to calculate savings bond
A Series EE bond's fixed rate compounds semiannually, so each completed six-month period multiplies the balance by (1 + half the annual rate). The calculator counts whole six-month periods from the purchase date to the valuation date, then compounds the purchase price by that many periods. Separately, the US Treasury guarantees that an EE bond purchased since May 2005 will be worth at least double its purchase price at its original 20-year maturity, so once the bond has been held 20 years or more, the calculator uses the higher of the compounded value or double the purchase price.
periods = floor(days held / 182.5); value = max(price x (1 + rate/2/100)^periods, price x 2 if 20+ years); interest = value - price
Worked example
A $1,000 Series EE bond purchased July 2016 with a 2.10% fixed annual rate, valued as of July 2026 (10 years held).
- Days held: 10 years = 3,652 days
- Completed semiannual periods: floor(3,652 / 182.5) = 20
- Rate per period: 2.10% / 2 = 1.05%
- Compounded value: $1,000 x 1.0105^20 = about $1,232.33
- 20-year doubling guarantee does not apply yet (only 10 years held), so the compounded value stands
Result: Estimated redemption value is about $1,232.33, or about $232.33 in interest after 10 years.
Frequently asked questions
How do I find my Series EE bond's fixed rate?
The fixed rate depends on the bond's issue date and does not change after purchase. Look up your bond's issue date and serial number on TreasuryDirect's Savings Bond Calculator or your paper bond, then enter the fixed rate shown there into this calculator.
What is the 20-year doubling guarantee?
The US Treasury guarantees that a Series EE bond purchased since May 2005 will be worth at least twice its purchase price at its original 20-year maturity. If the fixed rate alone would not double the value by then, the Treasury adds a one-time adjustment at the 20-year mark to make up the difference. This calculator applies that guarantee once the bond has been held 20 years or more.
Does this calculator work for I bonds?
No. I bonds combine a fixed rate with a separate inflation rate that resets every six months, which is a different product from the fixed-rate Series EE bond modeled here. An I bond's variable inflation component means its future value cannot be projected the same way; check TreasuryDirect directly for I bond redemption values.
How often does interest compound on an EE bond?
Semiannually. Every six months the bond's value grows by half of the annual fixed rate, applied to the balance at the start of that period, not just the original purchase price. This calculator counts the number of completed six-month periods since purchase to apply that compounding.
Can I cash in an EE bond before 20 years?
Yes, after a required one-year minimum holding period, though cashing in before 5 years forfeits the last 3 months of interest. Cashing in early also means you miss the 20-year doubling guarantee, so the redemption value would be based purely on the compounded fixed rate up to that point.