T-Bill Yield Calculator (Treasury Bill Return Calculator)
Already bought a T-Bill and want to know your actual return? Enter the amount you paid and the face value — this calculator works out your annual yield, profit, and the original discount rate instantly.
From your TreasuryDirect or brokerage statement. Must be less than the face value above.
Use "Custom" if you bought on the secondary market and have a specific number of days remaining.
What is T-Bill Yield and How Is It Calculated?
Your T-Bill yield is the real annual return on what you actually paid — not the "discount rate" listed at auction. Because the discount rate is calculated on the face value using a 360-day year, it understates your true return. Yield is calculated on your purchase price using 365 days, which makes it directly comparable to a savings account or CD rate.
Discount Rate vs Yield (Which One Shows Your Real Return?)
| Rate | Calculated on | Day basis | Use it for |
|---|---|---|---|
| Discount Rate | Face value ($10,000) | 360 days | Pricing at auction |
| Yield (BEY) | What you paid ($9,750) | 365 days | Comparing to savings / CDs |
Yield is always slightly higher than the discount rate. A 4.5% discount rate typically produces a yield of around 4.67%.
T-Bill Yield Formula (Simple Explanation)
- Your profit = Face Value − What you paid
- Annual return (BEY) = (Profit ÷ What you paid) × (365 ÷ Days) × 100
- Original discount rate = (Profit ÷ Face Value) × (360 ÷ Days) × 100
Step 1 — Your profit:
$10,000 − $9,750 = $250
Step 2 — Your annual return (BEY):
($250 ÷ $9,750) × (365 ÷ 182) × 100 = 5.153%
Step 3 — The original discount rate:
($250 ÷ $10,000) × (360 ÷ 182) × 100 = 4.945%
Your actual annual return (5.153%) is higher than the auction discount rate (4.945%) because it is calculated on the smaller amount you paid, not the full face value.
Which T-Bill Calculator Should You Use?
| If you know... | Use this calculator |
|---|---|
| The price you paid (from your statement) | T-Bill Yield Calculator — this page |
| The discount rate (from auction results) | T-Bill Calculator |
Why T-Bill Yield Matters for Your Returns
Savings accounts, CDs, and money market funds all quote their returns as an annual percentage on what you invested. The T-Bill discount rate does not use the same basis — so you cannot directly compare them. Yield (BEY) fixes this. If your T-Bill yield is 5.15% and a CD offers 5.0%, you can now see the T-Bill wins — and it has the added bonus of being exempt from state tax.
Compare T-Bills with CDs, Savings Accounts, and Bonds
Related Calculators
Learn more: What Are Treasury Bills — Complete Guide · Are T-Bills Worth It? · How Much Can I Earn from T-Bills?
Frequently Asked Questions (FAQ)
What is T-Bill yield?
T-Bill yield is the annual return you earn on your investment. It is calculated based on your purchase price and expressed on a 365-day basis, making it comparable to savings account or CD interest rates.
How is T-Bill yield calculated?
T-Bill yield is calculated using the formula: (Earnings ÷ Purchase Price) × (365 ÷ Days) × 100. This gives your annualized return based on what you actually paid.
Why is T-Bill yield higher than the discount rate?
T-Bill yield is higher because it is calculated on the lower purchase price, not the full face value. Since you invest less but earn the full difference, the percentage return is higher.
When should I use a T-Bill yield calculator?
Use a T-Bill yield calculator when you already know your purchase price and want to find your actual annual return. If you only know the rate, use a T-Bill calculator instead.