How this calculator works
T-bills are bought at a discount: the discount rate uses a 360-day year on face value, while the investment yield uses 365 days on the price you pay. Notes and bonds pay half the coupon every six months. Yield to maturity is approximated from the coupon plus the yearly share of any discount or premium.
Worked example
With the example values below: Investment yield, 4.093% (earn $200.00 in 26 weeks). Change any number above to run your own.
What you enter
| Input | Example |
|---|---|
| Security | Treasury bill |
| Face value | $10,000 |
| Purchase price | $9,800 |
| Term | 26 weeks |
Frequently asked questions
What is a Treasury bill?
A short-term loan to the US government, with maturities from 4 to 52 weeks. T-bills pay no coupon. You buy them below face value and receive the full face value at maturity, and the difference is your interest.
How do I buy Treasury bills?
Through TreasuryDirect, the government's site, where you bid at auction, or through a brokerage account, which can buy at auction or on the secondary market. Brokerages make it easier to sell before maturity.
Are Treasury bills taxable?
T-bill interest is subject to federal income tax but exempt from state and local income tax. That makes them worth more after tax than a CD or savings account at the same yield if you live in a high-tax state.
What's the difference between the discount rate and the investment yield?
The discount rate is the discount divided by face value on a 360-day year, which is how T-bills are quoted. The investment yield (bond-equivalent yield) divides the discount by the price you actually pay on a 365-day year. It's always a bit higher and is the one to compare with CDs and savings rates.
Grow what this calculator projects.
TruthSayer AI sends quantitative stock signals across valuations, earnings and dark-pool activity, each one traded in its own funded account first.
Estimates for planning only, not financial, tax or legal advice. Tax tools use 2026 federal figures (brackets, $16,100 / $32,200 standard deduction, $19,000 gift exclusion, $15M lifetime exemption). Rates shown as defaults are examples; replace them with quotes you actually receive.