Treasury Bills Calculator
Calculate T-Bill prices, Bank Discount Yield, and Bond Equivalent Yield
Calculate the purchase price of a T-Bill given the discount rate
T-Bill Parameters
Typically $10,000 minimum
Common: 28, 91, 182, or 364 days
The quoted discount rate from auction
Quick Reference
4-Week T-Bills: ~28 days
13-Week T-Bills: ~91 days
26-Week T-Bills: ~182 days
52-Week T-Bills: ~364 days
Results
Enter T-Bill details and click Calculate
Results will appear here
Understanding T-Bills
What are Treasury Bills?
T-Bills are short-term U.S. government debt securities with maturities of one year or less. They are sold at a discount from face value and mature at par. The difference between purchase price and face value is the investor's return. T-Bills are considered the safest investment.
Bank Discount Yield (BDY)
Formula: BDY = (Discount / Face Value) × (360 / Days). This is the quoted rate on T-Bills. BDY understates true return because: (1) it uses face value instead of purchase price in denominator, and (2) it uses 360-day year instead of 365 days.
Bond Equivalent Yield (BEY)
Formula: BEY = (Discount / Purchase Price) × (365 / Days). BEY provides the actual annualized return and is comparable to yields on other securities. Always higher than BDY for the same T-Bill. Use BEY when comparing T-Bills to bonds or other investments.
Practical Tips
T-Bills are auctioned weekly (4-week, 13-week, 26-week) and monthly (52-week) by the Treasury. You can buy directly from TreasuryDirect.gov with no fees. Interest is paid as the difference between purchase price and face value at maturity. Ideal for short-term cash management and preserving capital.