4 Week Treasury Bill Calculator

Financial Tools

Calculate the price, yield, and return of a 4-week (28-day) U.S. Treasury Bill.

Results Summary

Summary of key financial metrics for your 4-week T-Bill investment.

What is a 4 Week Treasury Bill Calculator?

A 4 week treasury bill calculator is a financial tool designed to determine the key metrics of a short-term U.S. government debt security known as a Treasury Bill (T-Bill). Unlike bonds, T-Bills are purchased at a discount to their face value and do not pay periodic interest. The investor’s return is the difference between the discounted purchase price and the face value received when the bill matures in 28 days. This calculator helps investors understand their potential earnings and the effective yield of their investment before they buy.

This tool is essential for investors looking for safe, short-term places to park their cash. By inputting the T-Bill’s face value and the auction’s discount rate, users can instantly see the purchase price, the total interest earned (the discount), and, most importantly, the Bond Equivalent Yield (BEY). The BEY annualizes the return, making it easy to compare the profitability of a 4-week T-Bill with other investment vehicles like savings accounts or other bonds.

4 Week Treasury Bill Formula and Explanation

The calculations behind a 4 week treasury bill calculator involve two primary steps: determining the purchase price from the discount rate and then calculating the investment yield based on that price. The formulas distinguish between the 360-day year used for bank discount calculations and the 365-day year used for the comparable Bond Equivalent Yield.

Formulas Used:

1. Discount Amount = Face Value × (Discount Rate / 100) × (28 / 360)
2. Purchase Price = Face Value – Discount Amount
3. Bond Equivalent Yield (BEY) = ((Face Value – Purchase Price) / Purchase Price) × (365 / 28) × 100

The first formula calculates the total discount (your profit) using the standard 360-day convention for money markets. The second simply subtracts this discount from the face value to find your cost. The third and most critical formula computes the BEY, which provides the annualized return on your investment, making it directly comparable to other interest-bearing securities.

Variables Table

Explanation of variables used in the 4-week T-Bill calculations.

Variable	Meaning	Unit	Typical Range
Face Value (FV)	The amount paid back at maturity.	USD ($)	$100 – $1,000,000+
Discount Rate (DR)	The annualized rate quoted at auction to determine price.	Percent (%)	0.1% – 6.0%
Days to Maturity (T)	The fixed term of the T-Bill.	Days	28 (Fixed for this calculator)
Purchase Price (PP)	The price you pay for the T-Bill.	USD ($)	Always less than Face Value
Bond Equivalent Yield (BEY)	The annualized investment yield for comparison.	Percent (%)	Often slightly higher than the Discount Rate

Practical Examples

Understanding the numbers with real-world scenarios makes the concepts clearer. Here are a couple of examples using the 4 week treasury bill calculator.

Example 1: Standard Investment

• Inputs:
  • Face Value: $10,000
  • Discount Rate: 5.0%
• Results:
  • Discount Amount: $10,000 * 0.05 * (28/360) = $38.89
  • Purchase Price: $10,000 – $38.89 = $9,961.11
  • Bond Equivalent Yield: (($38.89 / $9,961.11) * (365 / 28)) * 100 = 5.09%

Example 2: Higher Face Value and Different Rate

• Inputs:
  • Face Value: $50,000
  • Discount Rate: 4.5%
• Results:
  • Discount Amount: $50,000 * 0.045 * (28/360) = $175.00
  • Purchase Price: $50,000 – $175.00 = $49,825.00
  • Bond Equivalent Yield: (($175.00 / $49,825.00) * (365 / 28)) * 100 = 4.58%

How to Use This 4 Week Treasury Bill Calculator

Using this calculator is a straightforward process. Follow these steps to determine your potential T-Bill returns:

1. Enter Face Value: In the first field, input the total face value of the T-Bill you intend to purchase. This is the amount you’ll be paid at maturity. Common amounts are $1,000, $10,000, or more.
2. Enter Discount Rate: In the second field, enter the high rate or discount rate from the Treasury auction. This is not the final yield but is used to calculate your purchase price.
3. Review the Results: The calculator will automatically update. The most important figure for comparison is the Bond Equivalent Yield, which shows the annualized return. You will also see your exact Purchase Price and the total interest you’ll earn (Discount Amount).
4. Analyze the Chart and Table: Use the visual chart to quickly see the relationship between what you pay and what you get. The summary table provides a clean breakdown of all key metrics for your records.

Key Factors That Affect 4-Week T-Bill Rates

The rates offered on Treasury Bills are not static; they are influenced by a wide range of economic factors. Understanding these can provide context for the rates you see in our 4 week treasury bill calculator.

• Federal Reserve Monetary Policy: The Fed’s target for the federal funds rate is the most significant driver. When the Fed raises rates to fight inflation, T-Bill rates almost always follow suit.
• Inflation Expectations: If investors expect higher inflation, they will demand a higher yield on T-Bills to ensure their investment yields a real (after-inflation) return.
• Economic Growth: In a strong economy, demand for money increases, which can push rates up. Conversely, in a weak economy, the Fed may lower rates to stimulate growth, pushing T-bill yields down.
• Market Demand (Flight to Safety): During times of market volatility or uncertainty, investors often sell riskier assets like stocks and buy ultra-safe T-Bills. This increased demand can push prices up and yields down.
• Government Financing Needs: The amount of debt the U.S. Treasury needs to issue can impact rates. Larger auctions might require higher yields to attract enough buyers.
• Global Economic Conditions: Demand for U.S. T-Bills from foreign governments and investors also plays a role, influenced by global economic stability and interest rates in other countries.

Frequently Asked Questions (FAQ)

What’s the difference between the discount rate and the yield?

The discount rate is used to calculate the purchase price based on the face value and a 360-day year. The yield (specifically, the Bond Equivalent Yield) is your actual annualized return on investment, based on the price you paid and a 365-day year, making it better for comparing to other investments.

Are T-Bill earnings taxable?

Yes, the interest earned on T-Bills is subject to federal income tax. However, it is exempt from all state and local income taxes, which is a significant benefit for investors in high-tax states.

Why is a 360-day year used in the discount calculation?

This is a long-standing convention in money markets, known as the “bank year.” It simplifies certain calculations. However, for true yield comparison, the 365-day year is used to calculate the BEY.

What is the minimum investment for a T-Bill?

Through TreasuryDirect, the minimum purchase amount is $100, with multiples of $100 thereafter.

Can I lose money on a T-Bill?

If you hold the T-Bill to maturity, you cannot lose money, as it is backed by the full faith and credit of the U.S. government. You are guaranteed to receive the full face value. You could theoretically lose money only if you sell the bill on the secondary market before maturity for less than you paid.

What is Bond Equivalent Yield (BEY)?

BEY is a standardized metric that allows you to compare the yield of a discount security like a T-Bill to a traditional coupon-paying bond. Our 4 week treasury bill calculator highlights this as the primary result.

How does this calculator handle the maturity period?

This calculator is specifically designed for 4-week T-Bills and has the days to maturity hardcoded to 28 days to ensure accuracy for this specific security.

Where can I buy 4-week T-Bills?

You can buy them directly from the U.S. government through the TreasuryDirect website in a non-competitive bid, or through a bank or broker.