91 Day Treasury Bill Calculator: Real Price, Real Yield, No Guesswork
Enter the face value and quoted discount rate, and see exactly what you'd pay today, what you'd collect at maturity, and how the return truly compares once it's converted to a real annualized yield.
The amount you'll receive when the bill matures.
The annualized discount rate as quoted at auction or by your broker.
Why a Treasury Bill Doesn't Pay Interest the Usual Way
A bond pays you periodic interest and hands back your original principal at the end. A treasury bill flips that entirely, you buy it below its face value, collect nothing along the way, and simply receive the full face value the day it matures. The gap between what you paid and what you receive back is your entire return, which means the real work of understanding a T-bill is understanding exactly how that discount is calculated in the first place.
The Actual Discount Pricing Formula
The price you pay is the face value minus a discount, and that discount equals the face value multiplied by the quoted discount rate and the number of days in the term, all divided by 360. That 360 day denominator is a money market tradition rather than a true calendar convention, and it's exactly why the quoted discount rate alone slightly understates your true return, which is where bond equivalent yield comes in as the more honest comparison figure.
Why Bond Equivalent Yield Tells the Real Story
Bond equivalent yield takes your actual gain, the difference between face value and purchase price, divides it by what you actually paid rather than the face value, and annualizes using a true 365 day year instead of the 360 day money market convention. That combination makes it directly comparable to yields quoted on coupon bonds, CDs, and other interest-bearing investments, which is exactly why serious comparisons between a T-bill and any other fixed income option should lean on bond equivalent yield rather than the raw quoted discount rate.
Reading the Term Comparison
Toggle the comparison view on and you'll see your same face value and discount rate applied across several common bill terms side by side. This matters because term length interacts with the current shape of the yield curve, sometimes shorter bills pay more, sometimes longer ones do, and the only way to know which fits your situation is comparing the actual numbers rather than assuming longer always means more return.
Treasury Bills Around the World
The exact term lengths differ by country, the United States commonly issues 4, 8, 13, 26, and 52 week bills, while other government bond markets issue their own standard short-term maturities under different names, treasury bills, T-bills, or short-term government notes depending on the country. The discounting mechanics behind this calculator apply broadly to any short-term government security sold at a discount to face value, not just a specific national market.
Standards This Tool Follows
| Reference | How it's applied here |
|---|---|
| ISO 8601 | Your settlement date is entered and processed in the unambiguous YYYY-MM-DD format |
| ISO 4217 | Monetary figures follow standard international currency conventions |
| Money market day count conventions | Discount pricing uses the standard 360 day basis, with bond equivalent yield shown on a 365 day basis for comparison |
Frequently Asked Questions
How is the price of a 91 day treasury bill calculated?
The price equals face value minus a discount, where the discount is face value multiplied by the discount rate and the number of days in the term, divided by 360.
Why does the discount yield use a 360 day year instead of 365?
It's a long-standing money market convention that slightly understates the true annualized return, which is exactly why bond equivalent yield exists as a more accurate comparison figure.
What is bond equivalent yield and why does it matter?
It restates the bill's return using actual purchase price and a 365 day year, making it directly comparable to bonds and other interest-bearing investments quoted the standard way.
How does a 91 day bill compare to other treasury bill terms?
It depends on the current shape of the yield curve, sometimes shorter terms pay more, sometimes longer ones do, which is exactly why comparing actual numbers across terms matters more than assuming one length is always better.