Uses the official TreasuryDirect bank-discount method: rate on face value over 360 days, yield on purchase price over 365 days.
📊 This Rate Across All Standard T-Bill Tenors
| Tenor | Days | Purchase Price | Dollar Discount | CEY |
|---|
🏛️ What Is a US Treasury Bill?
A Treasury Bill, or T-Bill, is a short-term debt security issued by the US government with a maturity of one year or less. Unlike a bond, a T-Bill doesn't pay periodic interest at all — instead, you buy it below its face value and receive the full face value when it matures. The difference between what you pay and what you receive is your entire return. T-Bills are backed by the full faith and credit of the US government and have never defaulted, making them one of the safest short-term investments available to anyone in the US, UK, or elsewhere with access to TreasuryDirect or a brokerage.
📖 How to Use This Calculator (With Example)
Say you're considering a 13-week (91-day) T-Bill with a $10,000 face value at a 5.25% discount rate — a typical auction result. Set Solve For to "Price & Yield", select the 13-Week tenor, enter Face Value = 10000 and Discount Rate = 5.25, then click Calculate. The result shows a purchase price of about $9,867.29, a dollar discount (your profit) of about $132.71, and a coupon-equivalent yield of about 5.40% — noticeably higher than the quoted 5.25% discount rate, because your actual return is measured against what you paid, not the face value.
🔢 Formula Used (Official TreasuryDirect Method)
The discount rate is applied to the face value using a 360-day banking-year convention — this is the rate you'll see quoted at Treasury auctions. The coupon-equivalent yield (also called the investment rate) recalculates that same return on your actual purchase price using a 365-day year, which is what makes it directly comparable to a savings account APY, CD rate, or bond yield.
👥 Who This Is For
- Conservative investors parking cash safely while earning a competitive short-term rate
- Residents of high-tax states who benefit from the state and local tax exemption on T-Bill interest
- Anyone comparing T-Bills to a high-yield savings account or CD before deciding where to hold short-term cash
- Finance students learning the bank-discount pricing convention used across money markets
📊 ThinkForU vs Other T-Bill Calculators
| Feature | ThinkForU ⭐ | Typical Finance Sites |
|---|---|---|
| No Login Required | ✅ | ✅ |
| Zero Data Storage | ✅ | ❌ |
| Official TreasuryDirect Formula | ✅ | Often simplified |
| All Standard Tenors Compared at Once | ✅ | Usually one at a time |
| Reverse Calculation (from Purchase Price) | ✅ | Rarely offered |
| Downloadable Result | ✅ | ❌ |
What is a Treasury Bill (T-Bill)?
A short-term debt security issued by the US government, sold at a discount to face value. You buy it for less than face value and receive the full face value at maturity — the difference is your return.
What is the difference between the discount rate and the investment rate (CEY)?
The discount rate is quoted at auctions on face value using a 360-day year. The coupon-equivalent yield is calculated on the purchase price using a 365-day year, making it comparable to savings accounts and bonds — and always slightly higher than the discount rate.
Are T-Bills taxable?
Interest is subject to federal income tax but exempt from state and local income tax — an advantage for residents of high-tax states.
What T-Bill maturities are available?
The US Treasury currently offers 4, 8, 13, 17, 26, and 52-week bills, auctioned regularly throughout the year.
Can I lose money on a T-Bill?
Not if held to maturity — T-Bills are backed by the US government and have never defaulted. Selling early on the secondary market could result in a gain or loss depending on rate movements.
How is the T-Bill purchase price calculated?
Purchase price equals face value minus the discount, where the discount equals face value × discount rate × days to maturity ÷ 360.
Is a T-Bill better than a high-yield savings account?
It depends on current rates and your tax situation — T-Bills often win for high-tax-state residents due to the state tax exemption, while savings accounts offer more flexibility since T-Bills lock in a fixed term.