How to use the function TBILLEQ() in Excel and other spreadsheet tools for US Treasury Bills?

TBILLEQ() is a function provided in Microsoft Excel, Apache OpenOffice and other spreadsheet tools. It allows you to calculate the BEY (Bond Equivalent Yield) for a US Treasury Bill (T-Bill) with a given discount rate.

TBILLEQ(settlement, maturity, discount)

where:
  settlement = the settlement date after purchasing the T-Bill 
  maturity = the maturity date of the T-Bill 
  discount = the discount rate 

You can follow these steps to use the TBILLEQ() function:

1. Start Excel or other spreadsheet tool.

2. Enter the following formula in a cell:

=TBILLEQ("2024-12-26", "2025-06-26", 0.04170)

3. Take the output:

0.043189677 (4.3190% as the BEY)

4. Compare it with the following T-Bill transaction example:

CUSIP: 912797NW3
Type: 26-Week Bill 
Par Amount: $10,000.00 (Face value) 
Purchase Price: $9,789.18

Investment/Interest Rate: 4.319% (BEY - Bond Equivalent Yield)
Yield: 4.170% (Discount rate)
Price per $100: 97.891833

Discount: $210.82

Issue Date: 2024-12-26 (Settlement date)
Maturity Date: 2025-06-26

As you can see, the output of the TBILLEQ() function matches well with the BEY in this example.

You can also use our online calculator to validate the result. Click this link "T-Bill 912797NW3 settled on 2024-12-26 with a discount rate of 4.1700%, you will see the BEY of 4.3190% displayed.

You can also try the following 52-week T-Bill:

Term and Type of Security: 364-Day Bill 
CUSIP: 912797QD

High Rate: 3.820% (Discount rate)
Price: 96.137556
Investment Rate: 3.989% (BEY - Bond Equivalent Yield)

Issue Date: 2025-04-17
Maturity Date: 2026-04-16

Enter the following formula in a cell:

=TBILLEQ("2025-04-17", "2026-04-16", 0.03820)

output:
  0.039889895 (3.9890% as the BEY)

As you can see, the output of the TBILLEQ() function matches well with the BEY in this example.

You can also use our online calculator to validate the result. Click this link "T-Bill 912797NW3 settled on 2025-04-17 with a discount rate of 3.820%, you will see the BEY of 3.9890% displayed.

⇒ TBILLYIELD() Spreadsheet Function for T-Bill

⇐ TBILLPRICE() Spreadsheet Function for T-Bill

⇑ Spreadsheet Functions for T-Bill

⇑⇑ US Treasury Securities