Treasury bill yield calculator
Enter a bill by price or by quoted discount rate. This returns all three published conventions, the gaps between them in basis points, and a ladder mode that blends bills with a money-weighted rate instead of averaging rates that were never on the same basis.
Worked example — A 26-week bill at $979.40 per $1,000 face yields: 4.218%. Coupon-equivalent investment yield. The quoted bank discount rate on the same bill is 4.075%.
26-week bill: The exact boundary where the coupon-equivalent formula switches to the quadratic branch.
Advanced: your tax rate 3
No state tax: A resident of a state with no income tax, such as Texas, Florida, or Washington.
The discount basis divides the gain by face value and annualises on 360 days. The investment basis divides by the price actually paid and annualises on 365. They are different quantities that share a name in casual use.
The gaps, in basis points
Discount to coupon equivalent +14.3 bp, coupon equivalent to effective annual +4.5 bp, discount to effective annual +18.8 bp. An article that puts a 360-day discount rate beside a bank APY is off by the third of those numbers before it starts.
Where the price came from
At $979.40 for $1,000.00 of face, the implied discount quote is 4.075%. Switch the input above to go the other way.
Tax is where the comparison is settled
Bill interest is exempt from state and local income tax. At your rates, a fully taxable CD would have to pay 4.218% to leave you with what this bill leaves you with. The full four-way comparison lives on the tax-equivalent yield page.
Standard Treasury bill terms and their exact day count
The Treasury's own standard auction terms, in calendar days, which is what every yield formula on this page annualises against.
| Term | Days |
|---|---|
| 4-week | 28 |
| 8-week | 56 |
| 13-week | 91 |
| 17-week | 119 |
| 26-week | 182 |
| 52-week | 364 |
Bank discount rate, coupon-equivalent yield, and effective annual yield compared
One bill, on the 26-week default above, in four legitimate conventions. The gap between the discount rate and the effective annual yield is +18.8 bp of pure notation, not return.
| Convention | Rate | Divides by | Year | Use it for |
|---|---|---|---|---|
| Bank discount rate | 4.075% | Face value | 360 days | Reading an auction result. Nothing else. |
| Treasury coupon equivalent | 4.218% | Price paid | 365 days | Comparing a bill with a coupon-paying note or bond. |
| Simple 365-day yield | 4.218% | Price paid | 365 days | Identical to the coupon equivalent below 183 days. |
| Effective annual yield | 4.263% | Price paid, compounded | 365 days | Comparing with a savings account or a money-market APY. |
Is Treasury bill interest taxed by the state?
No. Treasury bill interest is exempt from state and local income tax, though it is fully taxable at the federal level. On the default bill above, its $20.60 of gain is taxed only once, at the federal rate; a fully taxable certificate of deposit paying the same after-tax amount would need to yield 4.218% before state and local tax.
What JMM thinks
The discount rate is a quoting convention inherited from paper, and it is the least useful of the three for a buyer. Use the coupon-equivalent yield when comparing a bill with a note or a bond, use the effective annual yield when comparing it with a savings account or a certificate of deposit, and use the discount rate only to read an auction result. Then settle the comparison after tax, since bill interest is exempt from state and local income tax and CD interest is not, which is worth more than the yield difference for a lot of readers in high-tax states.
What this does not model: this page quotes nothing, every price and term is yours to enter, and no bill price here comes from any market or auction. It does not model a sale before maturity, a broker's fee, or the reinvestment of maturing cash. For the full four-way after-tax comparison use the tax-equivalent yield calculator. For a security that pays coupons, use the bond yield calculator.
The next question after this one
Tax-equivalent yield calculatorCalculatorBills are state-tax exempt. This is what that exemption is worth against a CD or a muni at your rates.Open nextOther questions
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Auction-schedule aware ladders, rollover modelling, and a bill against money-market fund comparison are Pro features. The launch list sends one email at launch.