Treasury Bill Yield Calculator
US Treasury bills are the safest short-term instruments in the US financial system. They are sold at a discount and mature at face value, with the difference representing the investor's return. Two yield measures are used: the bank discount yield (the traditional money market convention) and the bond-equivalent yield (BEY), which makes T-bill returns comparable to coupon-bearing Treasury securities. This calculator computes both from the face value, purchase price, and days to maturity. Current T-bill auction results including discount rates are published by the U.S. Treasury after every weekly auction at TreasuryDirect.gov.
T-bill yield formulas
Discount = face value - purchase price
Discount yield = (discount / face value) * (360 / days)
Bond-equivalent yield = (discount / price) * (365 / days)
The discount yield uses face value as the investment base and a 360-day year (money market convention). The BEY uses purchase price as the base and a 365-day year, making it comparable to semiannual-coupon bond yields stated on a 365-day basis.
Investing in Treasury bills
- T-bills are backed by the full faith and credit of the US government and are considered the risk-free rate benchmark.
- Interest is exempt from state and local income taxes (but not federal income tax), per federal law.
- T-bills are available in minimum denominations of $100 through TreasuryDirect.gov.
- The Federal Reserve publishes H.15 selected interest rates daily, which include T-bill secondary market rates for 4, 13, and 26-week maturities.
- Money market funds typically hold T-bills and similar instruments; their yields closely track T-bill rates.
Frequently asked questions
What is a Treasury bill?
A Treasury bill (T-bill) is a short-term US government debt obligation with maturities of 4, 8, 13, 17, 26, or 52 weeks. T-bills are sold at a discount to face value and pay no coupon; the return is the difference between purchase price and face value at maturity.
What is the discount yield?
The discount yield (bank discount rate) measures the T-bill's return as a percentage of face value, annualized on a 360-day basis. It is the convention used in the money market: Discount yield = (face - price) / face * (360 / days).
What is the bond-equivalent yield?
The bond-equivalent yield (BEY) converts the T-bill return to an annual yield comparable to coupon-bearing Treasury notes and bonds. It is calculated on a 365-day basis using the purchase price as the denominator: BEY = (face - price) / price * (365 / days).
Why is BEY higher than the discount yield?
BEY is higher because it uses the (lower) purchase price as the denominator rather than the face value, and uses 365 days rather than 360. Because you invest less than face value but earn the full discount, your actual return as a percentage of investment is higher than the discount yield implies.
Where can I buy Treasury bills?
Treasury bills are sold at auction and can be purchased directly through the US Treasury's TreasuryDirect website (treasurydirect.gov) without fees, or through banks and brokers. Auction results, including discount rates and BEYs, are published by the US Treasury after each weekly auction.
Official sources
- U.S. Treasury: TreasuryDirect - Auction Results and T-Bill Rates.
- Federal Reserve: H.15 Selected Interest Rates.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.