How Much Does a $10,000 Treasury Bill Cost? Real Numbers

If you’ve ever Googled “how much does a $10,000 treasury bill cost,” the short answer is: you pay less than $10,000 when you buy it, and you get $10,000 back when it matures. The difference is your interest. But how much less? That depends on the discount rate from the auction, and it changes every auction. So let me walk you through the real math, give you a concrete example, and throw in some mistakes I’ve seen people make (and made myself).

What Is a Treasury Bill and How Does Pricing Work?

A Treasury bill (T-bill) is a short-term debt security issued by the U.S. government. It matures in one year or less. Unlike a coupon bond, a T-bill doesn’t pay interest checks. Instead, it’s sold at a discount to its face value. You pay, say, $970 today, wait a few months, then get $1,000 back. That $30 is your interest.

The Discount Pricing Mechanism

T-bills are quoted on a discount rate basis, not a dollar price basis. The discount rate is the annualized percentage deduction from face value. The formula for calculating the price (also called the “discount price”) is:

Why 360? It’s a standard market convention (based on a 360-day year) used for short-term instruments. The Treasury publishes auction results with the discount rate, but you can also see the “price per $100” on TreasuryDirect.

Why Do T-bills Sell Below Face Value?

It’s basically a loan from you to the government. The government doesn’t want to fuss with paying interest checks for a 4-week loan, so they just sell the loan at a discount. When it matures, they pay the full face value. The “discount” is effectively interest. That’s why the cost is always below $10,000 for a $10,000 bill — unless rates are zero or negative, which hasn’t happened for T-bills in the modern era.

How to Calculate the Cost of a $10,000 Treasury Bill

Let’s get to the numbers. You want to know the cost for a $10,000 face-value T-bill. The math is simple once you know the discount rate and the term.

The Simple Formula for T-Bill Price

Where:

- Discount Rate is the annualized yield from the Treasury auction (in decimal form). For example, 5% becomes 0.05.
- Days is the term of the bill (e.g., 28, 91, 182, or 364 days).

Real Example: 26-Week T-Bill at 5% Discount Rate

Let’s take a 26-week (182-day) T-bill auctioned at a discount rate of 5% (this is just an example — real rates fluctuate).

So you’d pay $9,747.22 today. In 26 weeks, the government pays you $10,000. Your interest is $252.78. That’s the “cost” — after you get the face value, you’ve earned $252.78.

Example with a Different Discount Rate

Rates change, so the price changes too. Let’s say the discount rate jumps to 5.5% for the same 182-day bill.

Now you pay $25.32 less because the discount is higher. Higher discount rates = lower cost. If the discount rate drops to 4%, you pay more upfront:

Interesting, right? The cost moves inversely with rates.

What About the “Price per $100” Quotes?

On TreasuryDirect, you’ll often see a price like “98.412” per $100 of face value. For a $10,000 bill, that means you pay 98.412 × 100 = $9,841.20. That’s just another way to quote the same discount. Don’t get confused.

Factors That Affect the Final Price for a $10,000 T-Bill

The price you pay isn’t random — it’s set by auction and market forces. Here’s what moves it.

Auction Bidding Process

T-bills are sold in weekly auctions. Bidders submit either competitive bids (they specify a discount rate) or non-competitive bids (they accept whatever the auction yields). Non-competitive bidders get the average discount rate and are guaranteed to receive their bills in full. Competitive bidders might get shut out if their rate is too high. For retail investors, the non-competitive route is the way to go — you get the same rate as the auction’s average.

The Fed’s Interest Rate Decisions

The Federal Reserve’s monetary policy has a direct hand in T-bill rates. When the Fed raises its benchmark rate, T-bill yields tend to climb, which lowers the upfront cost (because the discount rate is higher). When the Fed cuts rates, costs rise. You can’t predict the future, but you can watch Federal Reserve announcements to guess what might happen in T-bill auctions.

The Time to Maturity

Longer maturities usually come with higher discount rates to compensate for more time risk. A 4-week bill will have a much smaller discount (and a cost closer to $10,000) than a 52-week bill at the same annual yield — because the dollar discount is proportional to time.

Secondary Market vs. TreasuryDirect

Buying new issues through TreasuryDirect means you always get the auction-determined price. If you buy on the secondary market via a broker, the price can be slightly higher or lower depending on current market yields and spreads. In the secondary market, you might even pay a small commission (or “markup”), making the effective cost higher than the official T-bill price. For a clean $10,000 transaction, I prefer TreasuryDirect — no fees, no spread, direct from the source.

Step-by-Step: Buying a $10,000 T-Bill and Knowing Your Exact Cost

Here’s how I buy T-bills, and it’s the same for almost anyone in the U.S.

Step 1: Set Up a TreasuryDirect Account

TreasuryDirect is the official platform for buying Treasury securities. Go to treasurydirect.gov (a very official .gov site) and create an account. It takes about 10 minutes. You’ll link your bank account for purchases and redemptions. No fees.

Step 2: Place Your Bid

Once your account is set up, choose “Buy Direct” and pick a T-bill. For a $10,000 investment, enter $10,000. You’ll be asked whether you want to reinvest on maturity, and you can set that up if you like. Then, choose non-competitive bidding (unless you’re a pro). Note: you can buy in $100 increments, so $10,000 works nicely.

Step 3: See the Auction Results

The Treasury holds auctions regularly — 4-week and 8-week bills every Tuesday, 17-week every Wednesday, 13-week and 26-week every Monday, and 52-week every month. Results are posted the same day. When you log in, you’ll see the “price per $100” and the discount rate for your purchase.

Step 4: The Money You Actually Pay

Your account will be debited the day after the auction with the exact discount price. For a $10,000 face-value bill, you’ll see a debit like $9,735.50 (depending on the rate). That’s the cost. You’re done.

Common Mistakes When Estimating T-Bill Costs

Over the years, I’ve seen a few recurring errors. Here are the ones that really trip people up.

Mistake #1: Forgetting the Price Is Per $100

If the auction says “price 97.88” and you think that means $97.88 for a $100 bill, you’re right, but for a $10,000 bill you need to multiply by 100. That gives $9,788. Not $97.88. Simple, but easy to miss.

Mistake #2: Using the Simple Discount Rate Instead of the Investment Rate

T-bill yields are sometimes reported as the “investment rate” (which annualizes the actual earnings over the holding period) rather than the “discount rate.” The investment rate is usually higher than the discount rate. If you use the investment rate in the discount formula, you’ll get a price that’s lower than reality. Make sure you’re using the discount rate unless you’re doing a proper yield comparison.

Mistake #3: Confounding Face Value with Purchase Price

Some people budget $10,000 and are surprised to have a few hundred dollars left over. That’s great, but don’t spend that leftover until the bill matures. You actually have $10,000 invested once you include the discount, but your cash outlay is lower. Plan for that.

How Taxes Affect the Real Cost of a T-Bill

You don’t get to keep all the interest. T-bill interest is subject to federal income tax, but it’s exempt from state and local taxes. That’s a nice benefit if you live in a high-income-tax state. In practical terms, your “real cost” includes the tax you’ll owe on the $300 or so you earn. If you’re in the 24% federal bracket, you’ll owe roughly $24 on a $100 bill (face value) interest, but that’s not paid at purchase — it’s paid during tax season.

Also, if you buy in a tax-advantaged account like an IRA, you defer or eliminate that tax. That can make the effective after-tax cost lower. I always check whether my tax situation justifies buying in a taxable brokerage or inside an IRA. For small amounts, it’s often simpler to stick with a taxable account and just report the interest income.

Frequently Asked Questions

So, how much does a $10,000 Treasury bill cost? It’s not a fixed number — it’s a function of the discount rate and the bill’s term. At the end of the day, your “cost” is really the purchase price, usually between $9,700 and $9,900 for a typical rate environment. The rest is interest you earn when the bill matures. Understanding this simple math will save you from confusion and help you compare T-bills to other investments like CDs or high-yield savings. Happy investing — and don’t forget to check the actual auction results before you bid.