3 Month T Bill Calculator

Treasury Investing Tool

Estimate the purchase price, maturity value, dollar earnings, and annualized investment yield for a 13-week U.S. Treasury bill. This calculator uses the standard bank discount pricing convention for T-bills and helps you see how discount rates and days to maturity affect your return.

Calculator Inputs

Pricing Formula Price = Face × (1 – Rate × Days / Basis)

Maturity Value T-bills mature at full face value.

Income Source Earnings come from the discount between purchase price and par value.

How a 3 month T bill calculator works

A 3 month T bill calculator helps investors estimate the price and return of a short-term U.S. Treasury bill, commonly called a 13-week bill. These securities are backed by the full faith and credit of the U.S. government and are typically viewed as one of the lowest-credit-risk investments available in global markets. Instead of paying a periodic coupon like a Treasury note or bond, a Treasury bill is issued at a discount to face value and then pays its full face value at maturity. That discount is your return.

If you are comparing a T-bill with a high-yield savings account, money market fund, brokered CD, or a Treasury ETF, the calculator gives you a cleaner way to understand exactly what you are paying today and what you get back at maturity. For a standard 3-month bill, the maturity period is usually around 91 days, though the exact day count can vary by auction and settlement calendar. The key inputs are face value, quantity, quoted discount rate, and days to maturity. Once those are known, you can estimate purchase price, total cash outlay, dollar earnings, holding-period return, and annualized yield.

The standard pricing convention for T-bills is based on a bank discount rate, usually annualized on a 360-day basis. That can make T-bill quotes look slightly different from the APY figures you see on bank deposits. A good calculator bridges that gap by translating the discount quote into an annualized investment yield based on what you actually invested.

The core formula behind a 3 month Treasury bill

The basic discount pricing formula used for a Treasury bill is:

Price = Face Value × (1 – Discount Rate × Days to Maturity / Day Count Basis)

For example, assume a $1,000 face-value 3-month T-bill with a 5.20% discount rate and 91 days to maturity on a 360-day basis:

• Discount fraction = 0.0520 × 91 / 360 = 0.013144…
• Purchase price = $1,000 × (1 – 0.013144…) = about $986.86
• Maturity value = $1,000
• Earnings = $1,000 – $986.86 = about $13.14 per bill

If you buy 10 of those bills, your estimated purchase cost would be roughly $9,868.56, and your maturity value would be $10,000. Your total earnings would be about $131.44. This is why T-bills are often used by conservative investors, savers moving cash in stages, and institutions managing short-duration liquidity.

What inputs matter most

1. Face value: This is the amount you receive when the bill matures. Treasury bills are often purchased in $100 increments.
2. Quantity: Buying multiple bills scales your investment and your earnings linearly.
3. Discount rate: This quoted auction or market rate drives the discount from par.
4. Days to maturity: Even a small change in days can slightly change the price and annualized return.
5. Day-count basis: T-bills are normally quoted on a 360-day discount basis, but many investors like to compare returns using a 365-day investment basis.

This is why a specialized 3 month T bill calculator is useful. It gives you a practical estimate rather than forcing you to convert auction terminology by hand.

Why investors use 3 month T-bills

Short-term Treasury bills serve several roles in a portfolio. First, they are popular as a cash alternative when yields are attractive relative to savings accounts. Second, they are used to reduce interest-rate sensitivity because a 3-month maturity has very low duration compared with longer bonds. Third, they can be laddered so that part of your cash reserves matures frequently, which may help with flexibility and reinvestment planning.

• Capital preservation focus: Principal is returned at maturity if held to maturity and barring a U.S. government default scenario.
• Short duration: Price sensitivity is limited compared with longer-term bonds.
• Liquidity planning: Frequent Treasury bill auctions make short ladders relatively easy to build.
• Tax efficiency: Treasury interest is generally exempt from state and local taxes.
• Benchmark status: The 3-month bill is widely used as a reference rate in finance and macroeconomic analysis.

Historical context: recent 3-month T-bill rates

Yields on 3-month Treasury bills can move sharply as the Federal Reserve changes policy and money markets reprice. The table below summarizes recent annual average levels for the 3-month Treasury bill secondary market rate, based on Federal Reserve economic data. These figures help explain why a calculator is so useful: the same $10,000 investment can produce very different outcomes depending on the prevailing rate environment.

Year	Approx. Annual Average 3-Month T-Bill Rate	Rate Environment
2019	2.04%	Moderate short-term rates before the 2020 collapse
2020	0.67%	Emergency rate cuts pushed cash yields sharply lower
2021	0.05%	Near-zero rate environment
2022	1.66%	Rapid monetary tightening lifted short-term yields
2023	5.02%	High policy-rate environment boosted T-bill returns

Historical series can be reviewed through the Federal Reserve Bank of St. Louis FRED database and U.S. Treasury data. For official information, see FRED 3-Month Treasury Bill Secondary Market Rate.

Understanding discount yield vs investment yield

One of the most important concepts in any 3 month T bill calculator is the difference between the quoted discount yield and the investment yield. They are related, but they are not the same thing.

Discount yield is based on face value and typically annualized using a 360-day year. That is the quote convention used for Treasury bills. By contrast, investment yield is based on the amount of money you actually put to work, which is the purchase price. Because you invest less than face value, the investment yield is usually slightly higher than the quoted discount rate for the same bill.

Example:

• Face value = $10,000
• Purchase price = $9,868.56
• Earnings = $131.44
• Holding-period return = $131.44 ÷ $9,868.56 = about 1.33%
• Annualized investment yield on a 365-day basis = about 5.34%

That distinction matters when comparing a T-bill against a bank account APY, a money market mutual fund 7-day yield, or a broker CD quote. A robust calculator gives you both perspectives so your comparisons are more apples-to-apples.

Real-world Treasury bill terms and auction facts

The 3-month Treasury bill is part of a broader T-bill lineup offered by the U.S. Treasury. Knowing where the 13-week bill fits can help with laddering and reinvestment strategy.

Treasury Bill Term	Common Name	Typical Auction Frequency
4 weeks	1-month bill	Weekly
8 weeks	2-month bill	Weekly
13 weeks	3-month bill	Weekly
17 weeks	4-month bill	Weekly
26 weeks	6-month bill	Weekly
52 weeks	1-year bill	Every 4 weeks

Official Treasury information on auction schedules, terms, and how marketable securities work can be found at TreasuryDirect and through the U.S. Treasury interest rate statistics pages.

How to use this calculator effectively

To get the most accurate estimate, start with the exact bill term and quoted rate from the auction announcement, your brokerage platform, or TreasuryDirect reference material. Then enter the face value and quantity you intend to buy. If you are buying through an auction, remember that the final accepted price depends on the auction results. If you are buying in the secondary market, your execution price may differ slightly because of bid-ask spreads and market timing.

Best practices when modeling a purchase

1. Use the exact days to maturity whenever possible rather than assuming every 3-month period is identical.
2. Match the day-count basis to the convention you are comparing against.
3. Look at both dollar earnings and annualized yield.
4. If you are laddering, calculate several maturities side by side rather than only one purchase.
5. Consider taxes, settlement timing, and reinvestment assumptions before making a final decision.

3 month T-bill vs savings account vs CD

A 3-month T-bill can be attractive when short-term Treasury yields are above deposit rates, especially for taxable investors in high-tax states because Treasury interest is generally exempt from state and local income taxes. However, a savings account may offer same-day liquidity, and a CD may offer a fixed APY with FDIC insurance if held at an insured bank within coverage limits. Each tool fits a different job.

• T-bill: Marketable government security, short duration, state-tax advantage, fixed maturity date.
• Savings account: Very liquid, easy to access, variable rate, often lower yield than top market alternatives.
• CD: Fixed term, potential early-withdrawal penalties, FDIC coverage at insured institutions, rate may be competitive depending on term.

A calculator is especially helpful here because deposit products are often quoted as APY, while T-bills are quoted on a discount basis. Translating the quote into a purchase price and effective annualized investment yield makes the decision more practical.

Risks and limitations to keep in mind

Even though Treasury bills are considered among the safest investments from a credit standpoint, they are not completely free of practical considerations. If you hold the bill to maturity, you know the amount you will receive. But if you need to sell before maturity in the secondary market, the price may be slightly higher or lower than your purchase price depending on current yields and trading conditions.

• Reinvestment risk: When the bill matures, future yields may be lower.
• Opportunity cost: Locking money for 91 days could be less flexible than a liquid account.
• Tax planning: Federal taxes still matter, even if state and local taxes may not.
• Inflation risk: If inflation exceeds your return, real purchasing power can still decline.
• Execution differences: Actual auction outcomes and brokerage pricing can differ slightly from estimates.

Who should use a 3 month T bill calculator?

This type of calculator is useful for individual savers, retirees managing cash reserves, business owners with short-term surplus cash, fixed-income investors comparing front-end Treasury yields, and anyone building a rolling Treasury ladder. It is also useful for financial planners who need a quick estimate of net cash deployment and maturity proceeds for clients considering very short-term government securities.

Frequently asked questions

Is a 3 month T-bill the same as a 13-week Treasury bill?

Yes. In practice, the terms are often used interchangeably. Most 3-month Treasury bills are issued as 13-week bills, which typically means about 91 days to maturity.

Why is the purchase price lower than the maturity value?

T-bills are zero-coupon securities. You do not receive periodic interest payments. Instead, you buy the bill below face value and receive the full face value at maturity. The difference is your return.

Why does the annualized yield look higher than the discount rate?

The discount rate is based on face value and often uses a 360-day year. The investment yield is based on the lower purchase price you actually paid, and many investors annualize it on a 365-day basis. That usually produces a somewhat higher number.

Are 3 month T-bills taxable?

Income from Treasury bills is generally subject to federal income tax, but it is generally exempt from state and local income taxes. Tax rules can vary by situation, so consult a qualified tax professional for personalized advice.

Bottom line

A 3 month T bill calculator gives you a fast, accurate way to understand what a Treasury bill may cost today and what it may return at maturity. That is especially valuable when rates are changing quickly and when you are comparing Treasuries with cash alternatives. By entering the face value, quantity, discount rate, and exact days to maturity, you can estimate your purchase price, earnings, and annualized investment yield with far more clarity than you get from the quoted rate alone.

For official investing details, current auction conventions, and security descriptions, review the U.S. Treasury’s materials at TreasuryDirect.gov. For market history and research context, the Federal Reserve’s FRED series remains one of the most useful public references for short-term Treasury rate trends.