T-Bill Yield Calculator
Convert a Treasury bill’s purchase price and maturity into its discount yield and the coupon-equivalent (investment) yield you can compare to other bonds.
How it works
Bank discount = (face − price)/face × 360/days · Investment yield = (face − price)/price × 365/days
Treasury bills pay no coupon; you buy them below face value and collect the full face at maturity, and that gap is your return. The quoted "bank discount" rate understates the true return because it divides by face value and uses a 360-day year. The investment (coupon-equivalent) yield divides by the price you actually paid over a 365-day year, so it is the honest number to line up against CDs, notes and other bonds.
Worked example
Pay $985 for a $1,000 bill maturing in 182 days. The $15 gain is 1.523% over the period. Bank discount is 15/1000 × 360/182 = 2.97%; the investment yield is 15/985 × 365/182 = 3.05% — slightly higher, and the one to quote for comparisons.
Sources: U.S. Treasury — Bills
Frequently asked questions
Why are two different yields shown?
The bank discount yield is the traditional quote convention, but it flatters the return by using face value and a 360-day year. The investment yield uses your actual price and 365 days, so it reflects what you truly earn and compares fairly to other investments.
Are T-bill returns taxed?
Treasury bill interest is subject to federal income tax but is exempt from state and local tax, which can make the after-tax yield attractive for investors in high-tax states.
Can the price be above face value?
For a standard T-bill bought at auction or secondary market, no — bills trade at a discount and mature at par. This tool expects a price below face value and flags anything higher.
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Educational estimate, not investment advice. Markets involve risk of loss and future returns are never guaranteed.