T-Bill Yield Calculator
Know what you paid for a T-Bill? Enter your purchase price and face value to instantly calculate your annual yield, earnings, and back-calculated discount rate. This is the reverse of the standard calculator — useful when you already know your purchase price from a TreasuryDirect auction result or brokerage statement.
The full amount you receive at maturity. Minimum $100.
The discounted price you paid. Must be less than face value.
Choose the duration matching your T-Bill. Use "Custom" for secondary market purchases with remaining days that don't match a standard term.
What is T-Bill Yield?
T-Bill yield is the annualized return you earn on a Treasury Bill based on what you paid and what you receive at maturity. Because T-Bills are sold at a discount and redeemed at full face value, your yield is the difference expressed as an annual percentage.
Yield is always expressed on a 365-day basis (unlike the discount rate which uses 360 days) — making it directly comparable to APY on savings accounts and CDs.
Yield vs Discount Rate — What's the Difference?
T-Bills have two rates that are often confused:
| Rate | Based On | Day Count | Used For |
|---|---|---|---|
| Discount Rate | Face Value | 360-day year | Pricing the T-Bill at auction |
| Investment Yield | Purchase Price | 365-day year | Comparing returns to other investments |
T-Bill Yield Formula
- Earnings = Face Value − Purchase Price
- Investment Rate / BEY (%) = (Earnings ÷ Purchase Price) × (365 ÷ Days) × 100
- Discount Rate (%) = (Earnings ÷ Face Value) × (360 ÷ Days) × 100
Worked Example
Earnings = $10,000 − $9,750 = $250
Investment Rate (BEY) = ($250 ÷ $9,750) × (365 ÷ 182) × 100 = 5.153%
Discount Rate = ($250 ÷ $10,000) × (360 ÷ 182) × 100 = 4.945%
When to Use This Calculator vs the Standard T-Bill Calculator
| Calculator | You Know | You Want to Find |
|---|---|---|
| T-Bill Yield Calculator (this page) | Purchase price from your statement | Your actual annual yield |
| T-Bill Calculator | Discount rate from auction results | Purchase price and earnings |
Why Yield Matters
Yield lets you compare T-Bills directly against other investments like CDs, savings accounts, and money market funds — all of which express returns as an annual percentage on the amount invested. The discount rate alone is not useful for comparison because it uses a different basis.
Compare T-Bills With Other Investments
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
What is T-Bill yield?
T-Bill yield is the annualized return you earn based on your purchase price and face value. It is expressed on a 365-day basis, making it directly comparable to APY on savings accounts and CDs. Yield is always slightly higher than the stated discount rate.
How is T-Bill yield calculated?
Yield = (Earnings / Purchase Price) × (365 / Days) × 100. For example, if you paid $9,750 for a $10,000 T-Bill maturing in 182 days, your earnings are $250 and your annualized yield is approximately 5.15%.
Why is yield higher than the discount rate?
Because yield is calculated on the lower purchase price, not the full face value. You invest less than face value but earn a return based on that smaller amount — which makes the percentage return higher than the discount rate.
When should I use the yield calculator vs the T-Bill calculator?
Use the yield calculator when you already know your purchase price (from a brokerage statement or auction result) and want to find your actual annual return. Use the T-Bill calculator when you know the discount rate and want to find the purchase price and earnings.