T-bill calculator and ladder builder

Work out what a Treasury bill costs, what it pays and its investment rate. Then split your money into a ladder of bills, with a date for each one. The math follows the Treasury’s own rules. We checked it against 5,080 past Treasury auctions, from 2005 to 2026.

For bills held until they end · Free, no sign-up · The formula

Amount you get back

This is what you get back. You pay a little less.

Number of bills

Type 1 for one bill. Type 2 or more to build a ladder. Up to 13 for this term.

Term, in weeks

I know the

Investment rate

The rate you see first is a past average, not today’s rate. From 1928 to 2025, 3-month bills averaged 3.4% a year. Type the rate from your own auction or broker. See the Treasury’s daily bill rates

First bill starts on or after

13-week bills usually start on a Thursday. Leave it blank for the next one you can still bid for.

Federal tax rate

State and local tax rate

Both tax boxes are optional. Fill them in to see what you keep.

Each $10,000 bill costs $9,915.95 and pays $84.05 in 91 days at the 3.4% rate shown. A bill comes due every 3 weeks. After the last one, the wait is 4 weeks.

You pay in all

$39,663.80

You get back $40,000. Interest for one term: $336.20.

99.159454Price per $100

3.325%Discount rate

3.400%Investment rate

3.444%APY-style yield

3 weeksBetween bills

4 weeksWait after the last bill

Even ladders for 13-week bills:

Bill 1

Bill 2

Bill 3

Bill 4

Week 0Week 22

Each bar runs from the day you buy a bill to the day it pays you back. Bills come due 3 weeks apart. Then the wait is 4 weeks.

Save my plan

Hypothetical illustration based on your inputs. Not a prediction, a recommendation, or the performance of any Amaltash strategy.

How it works: each bill is priced with the Treasury’s formulas at the rate or price you enter, and held until it ends. Dates use the usual issue weekday for the term. Real rates are set at each auction.

Results change each time you change an input.

Real rates change. Fees, taxes and penalties are not included, and a rate you are offered can differ from this one.

Your bills, one by one

Bill	Buy date	Due date	Days	Face value	You pay	Interest
1	Week 0	Week 13	91	$10,000	$9,915.95	$84.05
2	Week 3	Week 16	91	$10,000	$9,915.95	$84.05
3	Week 6	Week 19	91	$10,000	$9,915.95	$84.05
4	Week 9	Week 22	91	$10,000	$9,915.95	$84.05
Total	—	—	—	$40,000	$39,663.80	$336.20

Dates use the usual issue weekday. A holiday can move a date.

Every due date for the next 12 months

Due date	Bill	Face value
Week 13	1	$10,000
Week 16	2	$10,000
Week 19	3	$10,000
Week 22	4	$10,000
Week 26	1	$10,000
Week 29	2	$10,000
Week 32	3	$10,000
Week 35	4	$10,000
Week 39	1	$10,000
Week 42	2	$10,000
Week 45	3	$10,000
Week 48	4	$10,000
Week 52	1	$10,000
Week 55	2	$10,000
Week 58	3	$10,000
Week 61	4	$10,000

This list assumes you renew each bill for the same term. A renewed bill gets the rate of its own auction, so no interest is shown.

One $10,000 bill at every term

Term	Days	Price per $100	You pay	Interest	Discount rate	Investment rate
4 weeks	28	99.739857	$9,973.99	$26.01	3.345%	3.400%
6 weeks	42	99.610292	$9,961.03	$38.97	3.340%	3.400%
8 weeks	56	99.481063	$9,948.11	$51.89	3.336%	3.400%
13 weeks	91	99.159454	$9,915.95	$84.05	3.325%	3.400%
17 weeks	119	98.903660	$9,890.37	$109.63	3.317%	3.400%
26 weeks	182	98.332920	$9,833.29	$166.71	3.298%	3.400%
52 weeks	364	96.693632	$9,669.36	$330.64	3.270%	3.400%

Example math at the rate shown. These are not current rates.

How to use the T-bill calculator

Type the amount you want back when the bill ends. Pick a term from 4 to 52 weeks. Then type the rate from your auction or broker. The calculator shows what you pay today, the interest you earn, and the date the bill pays you back.

A Treasury bill, or T-bill, is a short loan to the US government. You pay a bit less than the bill is worth. At the end you get the full amount.

Amount: the total you get back at the end. It is called the face value.
Number of bills: type 1 for one bill. Type 2 or more to build a ladder.
Term: how long each bill runs.
Rate type: pick the number you have. It can be the investment rate, the discount rate, or the price for each $100.
Tax rates: add them to see what you keep after tax. You can leave them blank.

Word	What it means
Face value	The full amount the bill pays you at the end
Term	How long the bill runs, in weeks
Discount rate	The rate an auction sets, measured against the face value
Investment rate	The same interest, measured against the price you pay

The rate you see first is a past average, not today’s rate. From 1928 to 2025, 3-month bills averaged 3.4% a year.

How is the price of a T-bill calculated?

A T-bill sells for less than its face value. The Treasury takes the discount rate, multiplies it by the days in the term, and divides by 360. That share comes off the face value. A $1,000 bill for 26 weeks at a made-up 4% rate costs $979.78.

P = F \left(1 - \frac{d \times t}{360}\right)

In words: Take the face value. Take off the rate times the days, divided by 360.

$P$: the price you pay
$F$: the face value, paid to you when the bill ends
$d$: the discount rate, as a decimal
$t$: the days until the bill ends

Here is a $10,000 bill for 13 weeks, which is 91 days. The 4% rate is made up for the example.

Multiply the rate by the days: 0.04 × 91 = 3.64.
Divide by 360: 3.64 ÷ 360 = 0.010111.
Take that share off the face value: $10,000 × (1 − 0.010111) = $9,898.89.
The gap is your interest: $10,000 − $9,898.89 = $101.11.

The Treasury shows the same math with its own example. A $1,000 bill for 26 weeks at a 0.145% discount rate sells for $999.27. It rounds the price for each $100 to six decimal places.

Do you know the investment rate and not the discount rate? Then the price comes from this formula. It works for bills of 183 days or fewer.

P = \frac{F}{1 + i \times \frac{t}{y}}

In words: Multiply the rate by the days. Divide by the days in the year. Add one. Then divide the face value by the result.

$P$: the price you pay
$F$: the face value, paid to you when the bill ends
$i$: the investment rate, as a decimal
$t$: the days until the bill ends
$y$: the days in the year after the bill starts: 365 or 366

A price is what a later sum is worth today.

Work out what a sum is worth later with the future value calculator →

Discount rate vs investment rate: what is the difference?

Both rates describe the same bill. The discount rate compares your interest with the face value and uses a 360-day year. The investment rate compares it with the price you paid and uses a 365-day year. So the investment rate is the higher one. Use it to compare with a bank.

d = \frac{F - P}{F} \times \frac{360}{t}

In words: Divide your interest by the face value. Then multiply by 360 and divide by the days.

$d$: the discount rate, as a decimal
$F$: the face value, paid to you when the bill ends
$P$: the price you pay
$t$: the days until the bill ends

i = \frac{F - P}{P} \times \frac{y}{t}

In words: Divide your interest by the price you paid. Then multiply by the days in the year and divide by the days in the term.

$i$: the investment rate, as a decimal
$F$: the face value, paid to you when the bill ends
$P$: the price you pay
$y$: the days in the year after the bill starts: 365 or 366
$t$: the days until the bill ends

You may see other names for these two rates.

Bank discount rate: the same as the discount rate.
Coupon equivalent: the same as the investment rate. You will see this name on the Treasury’s page of daily rates.
Bond equivalent yield: one more name for the investment rate.

The gap between the two rates grows with the rate and with the term. This table shows the gap in percentage points, in a 365-day year. The rates are made up.

Discount rate	4 weeks	6 weeks	8 weeks	13 weeks	17 weeks	26 weeks	52 weeks
1%	0.015	0.015	0.015	0.016	0.017	0.019	0.022
2%	0.031	0.033	0.034	0.038	0.041	0.048	0.059
3%	0.049	0.052	0.056	0.065	0.072	0.089	0.113
4%	0.068	0.075	0.081	0.097	0.110	0.139	0.183
5%	0.089	0.099	0.109	0.134	0.155	0.201	0.270
6%	0.112	0.126	0.141	0.177	0.206	0.274	0.375
8%	0.162	0.188	0.213	0.279	0.331	0.453	0.639

Real auctions show the same pattern. The next table covers the 1,399 regular bill auctions issued from November 1, 2021 to October 20, 2026. The source is the US Treasury. These are past results, not a forecast.

Term	Auctions	Issued on the usual weekday	Ran the usual days	Rate gap: middle / widest
4 weeks	260	Tuesday, 258 of 260	98.5%	0.073 / 0.124
6 weeks	87	Thursday, 83 of 87	89.7%	0.072 / 0.085
8 weeks	260	Tuesday, 258 of 260	98.5%	0.087 / 0.137
13 weeks	259	Thursday, 249 of 259	92.7%	0.105 / 0.164
17 weeks	209	Tuesday, 207 of 209	98.1%	0.126 / 0.187
26 weeks	259	Thursday, 249 of 259	92.7%	0.148 / 0.240
52 weeks	65	Thursday, 62 of 65	95.4%	0.179 / 0.303

The APY-style yield goes one step more. It is the yearly rate if you could buy the same bill at the same price all year. The next bill gets its own rate, so read it as math and not as a forecast.

\text{APY-style yield} = \left(\frac{F}{P}\right)^{y / t} - 1

In words: Divide the face value by the price. Raise it to the number of terms that fit in a year. Then take away one.

$F$: the face value, paid to you when the bill ends
$P$: the price you pay
$y$: the days in the year after the bill starts: 365 or 366
$t$: the days until the bill ends

Turn any rate into an APY with the APR calculator →

How much interest does a T-bill pay?

Your interest is the face value minus the price you paid. You get it all at the end, in one payment. Take a made-up 4% discount rate. A $10,000 bill then pays $31.11 over 4 weeks, $101.11 over 13 weeks, $202.22 over 26 weeks, and $404.44 over 52 weeks.

\text{interest} = F - P

In words: Take the price you paid away from the face value.

$F$: the face value, paid to you when the bill ends
$P$: the price you pay

The table shows examples at a made-up 4% discount rate. It is not a current rate.

Face value	4 weeks	13 weeks	26 weeks	52 weeks
$1,000	$3.11	$10.11	$20.22	$40.44
$5,000	$15.56	$50.56	$101.11	$202.22
$10,000	$31.11	$101.11	$202.22	$404.44
$25,000	$77.78	$252.78	$505.56	$1,011.11
$50,000	$155.56	$505.56	$1,011.11	$2,022.22
$100,000	$311.11	$1,011.11	$2,022.22	$4,044.44

A bill pays simple interest, one time. Nothing is added along the way.

Check plain interest with the simple interest calculator →

Leave the interest in and see it grow on the compound interest calculator →

What terms do Treasury bills come in, and when are they sold?

Treasury bills come in seven terms: 4, 6, 8, 13, 17, 26 and 52 weeks. The Treasury sells every term each week, except the 52-week bill. That one is sold every four weeks. The smallest bill you can buy is $100, and bills go up in $100 steps.

These facts come from TreasuryDirect, as of November 12, 2026. Three words help here.

Auction: the sale where the rate for a new bill is set.
Issue date: the day the bill starts and you pay for it.
Non-competitive bid: you agree to take the rate the auction sets. You can buy up to $10 million of one bill this way.

Term	Usual days	Sold	Auction day	Issue day
4 weeks	28	Every week	Thursday	Tuesday
6 weeks	42	Every week	Tuesday	Thursday
8 weeks	56	Every week	Thursday	Tuesday
13 weeks	91	Every week	Monday	Thursday
17 weeks	119	Every week	Wednesday	Tuesday
26 weeks	182	Every week	Monday	Thursday
52 weeks	364	Every four weeks	Tuesday	Thursday

A holiday can move a day. The calculator uses the usual issue day for the dates it shows.

The 6-week bill is the newest term. In the Treasury’s auction data, the first regular one was issued on February 20, 2025. The 17-week bill started on October 25, 2022.

How to build a T-bill ladder with this calculator

A ladder is a set of bills that end on different dates. Type your total amount, then choose how many bills and which term. The calculator splits the money into equal bills in $100 steps. It lists each buy date and each date a bill pays you back.

Type the total for the whole ladder.
Set the number of bills. Each bill is one step of the ladder.
Pick one term. Every bill in the ladder uses it.
Read the dates. The first bill starts on the next issue day you can still bid for.
Check the wait after the last bill. Tap an even ladder if you want every wait to match.
Save the dates to your calendar.

\text{face value per bill} = \left\lfloor \frac{A}{n \times 100} \right\rfloor \times 100

In words: Divide your total by the number of bills. Then round down to a whole $100.

$A$: the total amount you type
$n$: the number of bills

So $10,000 across 3 bills is $3,300 each, with $100 left over. And $25,000 across 4 bills is $6,200 each, with $200 left over.

TreasuryDirect can renew a bill for you when it ends. It only renews into a bill of the same term. As of November 12, 2026, you can set up this many renewals.

Term	Renewals you can set	Weeks covered in all
4 weeks	25	104
6 weeks	16	102
8 weeks	10	88
13 weeks	7	104
17 weeks	6	119
26 weeks	3	104
52 weeks	1	104

People build a ladder so cash comes back on a schedule. A ladder also spreads the money over more than one auction rate.

Size your cash cushion with the emergency fund calculator →

How many bills does a T-bill ladder need?

It depends on how often you want money back. More bills means cash comes due more often, in smaller amounts. The waits are all the same length when the term, divided by the number of bills, is a whole number of weeks. If not, one wait is longer.

\text{weeks apart} = \left\lfloor \frac{T}{n \times c} \right\rfloor \times c

In words: Divide the term in weeks by the number of bills. Then round down to a whole number of auctions.

$T$: the term of each bill, in weeks
$n$: the number of bills
$c$: the weeks between auctions: 4 for 52-week bills, 1 for the rest

\text{last wait} = T - (n - 1) \times \text{weeks apart}

In words: Start with the term. Take off the weeks apart, once for each bill after the first.

$T$: the term of each bill, in weeks
$n$: the number of bills

Term	Most bills	Even ladders (bills → weeks apart)	What 4 bills give
4 weeks	4	1 → 4, 2 → 2, 4 → 1	1 week apart, even
6 weeks	6	1 → 6, 2 → 3, 3 → 2, 6 → 1	1 week apart, then 3
8 weeks	8	1 → 8, 2 → 4, 4 → 2, 8 → 1	2 weeks apart, even
13 weeks	13	1 → 13, 13 → 1	3 weeks apart, then 4
17 weeks	17	1 → 17, 17 → 1	4 weeks apart, then 5
26 weeks	26	1 → 26, 2 → 13, 13 → 2, 26 → 1	6 weeks apart, then 8
52 weeks	13	1 → 52, 13 → 4	12 weeks apart, then 16

Thirteen and 17 are prime numbers. So those two terms make an even ladder only with one bill, or with a new bill each week.

Want cash back about once a month? These ladders come close.

13-week bills, 3 bills: 4 weeks apart, then a 5-week wait.
26-week bills, 6 bills: 4 weeks apart, then a 6-week wait.
52-week bills, 13 bills: 4 weeks apart, with equal waits.

Are T-bills taxed by your state?

No. The IRS says the federal government taxes the interest on Treasury bills. States and cities do not charge income tax on it. Bank interest is usually taxed by both. So a bill can keep more after tax than a bank account with the same rate.

This formula finds the bank rate that leaves you the same amount after tax.

\text{bank rate to match} = i \times \frac{1 - f}{1 - f - s}

In words: Take one minus your federal rate. Divide it by one minus both tax rates. Then multiply by the investment rate.

$i$: the investment rate, as a decimal
$f$: your federal tax rate, as a decimal
$s$: your state and local tax rate, as a decimal

The table uses a 4.00% bill and made-up tax rates. It assumes you do not deduct state tax on your federal return.

Federal rate	State 0%	3%	5%	7%	9.3%	13.3%
12%	4.00%	4.14%	4.24%	4.35%	4.47%	4.71%
22%	4.00%	4.16%	4.27%	4.39%	4.54%	4.82%
24%	4.00%	4.16%	4.28%	4.41%	4.56%	4.85%
32%	4.00%	4.18%	4.32%	4.46%	4.63%	4.97%

Here is the same idea in dollars. Say a bill pays $202.22 of interest. Your federal rate is 22% and your state rate is 5%. The bill owes $44.49 of federal tax and no state tax, so you keep $157.73. The same interest from a bank owes $10.11 more, in state tax. You keep $147.62.

A common shortcut divides the rate by one minus the state rate. With these tax rates it says 4.21%. The full math says 4.27%.

Your broker or TreasuryDirect reports the interest on Form 1099-INT, in box 3. You report it for the year the bill ends. This is not tax advice.

Tax is one part of the choice. A bank account lets you take money out when you like. A bill ties it up until the bill ends, unless you sell it at the market price.

Compare a bill with a CD on the CD calculator →

See what cash in a savings account earns on the high-yield savings calculator →

Why do 52-week bills and leap years use different math?

Two small Treasury rules change the investment rate. A bill longer than 183 days uses a longer formula. That lets you compare it with bonds, which pay interest every six months. And the year counts 366 days when a February 29 falls in the year after the bill is issued.

P \left[1 + \left(t - \frac{y}{2}\right) \frac{i}{y}\right] \left(1 + \frac{i}{2}\right) = F

In words: Grow the price for half a year at half the rate. Then grow it for the days left over. You must land on the face value.

$P$: the price you pay
$t$: the days until the bill ends
$y$: the days in the year after the bill starts: 365 or 366
$i$: the investment rate, as a decimal
$F$: the face value, paid to you when the bill ends

i = \frac{-b + \sqrt{b^2 - 4ac}}{2a} \qquad a = \frac{t}{2y} - 0.25 \quad b = \frac{t}{y} \quad c = \frac{P - F}{P}

In words: This is the line above, solved for the rate. The calculator does this step for you.

$i$: the investment rate, as a decimal
$a,\ b,\ c$: three helper numbers, set by the days and the price

These examples use a made-up 4% discount rate.

A 52-week bill: the short formula says 4.226%. The longer Treasury formula says 4.183%.
A 13-week bill: the investment rate is 4.097% in a 365-day year. It is 4.108% in a 366-day year.
A bill issued on February 25, 2027 counts 365 days. A bill issued on March 4, 2027 counts 366.

The calculator picks the right formula and the right year for each bill.

How we checked this calculator

We ran our formulas on every Treasury bill auction we could test. The bills were issued from January 2005 to October 2026. That is 5,080 auctions. Our price matched the Treasury’s price to six decimal places in all of them. Our investment rate matched to three decimal places in all of them.

The results come from the Treasury’s Fiscal Data site. We pulled them on November 12, 2026. They are past results, not a forecast.

The small rules matter. A plain calculator that skips them gets real auctions wrong.

A fixed 365-day year gets the rate wrong in 826 of the 1,086 auctions with a leap day in the year ahead.
The short formula gets the rate wrong for 154 of the 259 bills longer than 183 days.
The investment rate was never below the discount rate in any of the 5,080 auctions.

A match on past auctions checks our math. It does not tell you what a future bill will pay.

T-bill formulas for a spreadsheet

You can check any result in a spreadsheet. Put the face value in A1, the discount rate in A2 and the days in A3. The price is A1 times one minus A2 times A3 over 360. The interest is A1 minus that price.

Type the rate as a decimal, so 4% is 0.04. Then use these cell formulas.

Price, in cell B1: =A1*(1-A2*A3/360)
Interest, in cell B2: =A1-B1
Investment rate, in cell B3: =(B2/B1)*365/A3
Investment rate in one step: =365*A2/(360-A2*A3)

The last two lines work for bills of 183 days or fewer in a 365-day year. Both give 4.097% for a 4% discount rate and 91 days.

What this calculator leaves out

The calculator shows the math for bills bought at auction and held to the end. It leaves out broker fees and price gaps. It does not know today’s rates or holiday date shifts. Tax results use the rates you type and are not tax advice.

Selling early means taking the market price. It can be less than you paid.
Every new bill gets the rate of its own auction. A renewed bill can pay more or less than the last one.
Rising prices can outrun the interest. Then your money buys less later.
The rate you see first is a past average, not today’s rate. From 1928 to 2025, 3-month bills averaged 3.4% a year.

Want the long view? One page shows how bills did next to bonds and stocks.

See how bills, bonds and stocks grew since 1928 on the investment calculator →

Questions people ask

How do you calculate the price of a Treasury bill?

Multiply the discount rate by the days to maturity, divide by 360, and take that share off the face value. For a $10,000 bill at a made-up 4% rate for 13 weeks (91 days), the price is $9,898.89. The $101.11 gap is your interest.

What is the difference between the discount rate and the investment rate?

The discount rate measures interest against the face value over a 360-day year. The investment rate measures it against the price you paid over a 365-day or 366-day year. In 5,080 past Treasury auctions, from 2005 to 2026, the investment rate was never the lower one. Past results, not a forecast.

How much does a $10,000 T-bill pay?

It depends on the rate and the term. Take a 26-week bill. At a made-up discount rate of 3%, a $10,000 bill pays $151.67. At 4% it pays $202.22, and at 5% it pays $252.78. You get the interest when the bill ends.

Are T-bills exempt from state tax?

Yes. The IRS says the interest is taxed by the federal government. It is exempt from all state and local income taxes. Your broker or TreasuryDirect reports it on Form 1099-INT, in box 3. This is not tax advice.

What is the minimum to buy a T-bill?

The minimum is $100. TreasuryDirect sells bills in $100 steps, up to $10 million in one auction for a non-competitive bid. That is why the ladder rounds each bill down to the nearest $100 and shows any money left over.

How often are T-bills auctioned?

Most are auctioned every week. That covers the 4, 6, 8, 13, 17 and 26-week bills. The 52-week bill is auctioned every four weeks. A holiday can move a date. Check the Treasury’s auction calendar before you plan to buy.

How many bills do I need for a T-bill ladder?

Two bills are enough to make a ladder. With same-term bills, an even ladder needs a bill count that divides the term. Thirteen-week bills only split evenly into 13 weekly bills. Eight-week bills split evenly into 2, 4 or 8.

Where do I find today’s T-bill rate?

The Treasury posts it. You can look up the result of every auction on its TreasuryDirect site. The Treasury also posts bill rates each day, in two forms: the bank discount rate and the coupon equivalent. Rates change at each auction, so this page does not quote one.

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Reviewed by Tavish Sharma, CFA · Last reviewed Nov 12, 2026

Published by Amaltash Advisors LLC, an SEC-registered investment adviser

Sources

Treasury Bills, TreasuryDirect, US Department of the Treasury
Understanding Pricing and Interest Rates, TreasuryDirect, US Department of the Treasury
Price, Yield and Rate Calculations for a Treasury Bill, TreasuryDirect, US Department of the Treasury
31 CFR Part 356, Appendix B, section VI: price, discount rate and investment rate for Treasury bills, Electronic Code of Federal Regulations (eCFR)
General Auction Timing, TreasuryDirect, US Department of the Treasury
How Auctions Work, TreasuryDirect, US Department of the Treasury
Reinvesting a Treasury Marketable Security, TreasuryDirect, US Department of the Treasury
Daily Treasury Bill Rates, US Department of the Treasury
Treasury Securities Auctions Data, Fiscal Data, US Department of the Treasury
Publication 550, Investment Income and Expenses, Internal Revenue Service
Topic no. 403, Interest received, Internal Revenue Service
Historical Returns on Stocks, Bonds and Bills, 1928–2025, NYU Stern School of Business (Aswath Damodaran)