AtlasCalcsUtility Calculation Suite
2026-09-22 7 min read

T-Bill Calculator

T-Bill price, discount and investment yield for a treasury bond. Live calculator with worked steps, charts and formulas.

Calculator

T-Bill Face Value
$
Discount (Bank) Rate(%)
%
Days to Maturity(days)
days

This treasury & government calculator runs on standard bond mathematics: coupons and face value discounted at the market yield with 2 payment(s) per year. Money is calculated at full precision and rounded only for display.

Results

Optimal

Purchase Price

$9,874

Profit at Maturity

$126

Bank Discount Rate

5.00%

Investment (Bond-Equivalent) Yield

5.13%

Days to Maturity

91

Live results update as you type — currently showing purchase price of $9,874. Replace the defaults with your own quote for an exact comparison.

Visualizations

Discount vs Proceeds

Discount1%
Price paid99%

Formula

Bank-discount pricing on a 360-day year; investment yield restates on 365 days for comparison with coupons.

Price = Face × (1 − d·days/360); Inv = (Profit/Price) × 365/days

Variables

SymbolNameUnitDescription
dDiscount ratepercentBank discount
daysDays to maturitydaysTerm

Explanation

What a T-Bill costs, the profit at maturity and both yield quotes.

Step-by-Step Calculation

Follow each step to understand how the result is calculated from your inputs.

Step 1

Discount the face by the bank-discount formula.

Price = Face × (1 − d·days/360)
Discount:5.00%
Result: $9,873.61
Step 2

Profit is face minus price.

Profit = Face − Price
Result: $126.39
Step 3

Convert to bond-equivalent yield on a 365-day base.

Inv = (Profit/Price) × 365/days
Result: 5.13%
Final Answer
$9,874

Worked Examples

See how the calculator works with different scenarios.

Scenario

The t-bill calculator run on the values above, showing the full calculation path rather than only the answer.

Inputs

T-Bill Face Value:10000
Discount (Bank) Rate:5
Days to Maturity:91

Calculation

1. Discount the face by the bank-discount formula. → $9,873.61 2. Profit is face minus price. → $126.39 3. Convert to bond-equivalent yield on a 365-day base. → 5.13%

Result

Purchase Price: $9,874

Interpretation

Pay $9,873.61 for $10,000 in 91 days; investment yield 5.13%.

Understanding Your Result

Your Result: Purchase Price: $9,874

What This Means

What a T-Bill costs, the profit at maturity and both yield quotes.

Why It Matters

Pay $9,873.61 for $10,000 in 91 days; investment yield 5.13%.

Professional Interpretation

Pay $9,873.61 for $10,000 in 91 days; investment yield 5.13%.

How this is calculated

Bank-discount pricing on a 360-day year; investment yield restates on 365 days for comparison with coupons.

What drives the result

T-Bills are sold at a discount with no coupons; notes and bonds pay coupons. Municipal interest is typically federal-tax exempt, so compare on a taxable-equivalent basis. Savings bonds (I and EE) accrue or composite with inflation and reward holding to term.

Recommendations

  • •T-Bills are state/local-tax exempt — compare after-tax with CDs.
  • •Roll 4/8/13/17/26/52-week bills to build a cash ladder.

Educational Content

Introduction

Sovereign and government-linked bonds (Treasuries, T-Bills, municipals, savings bonds) share one trait: the credit backstop is a government. Pricing still follows present value, but tax treatment, auction mechanics and inflation linkage change the comparison.

Concept Explanation

T-Bills are sold at a discount with no coupons; notes and bonds pay coupons. Municipal interest is typically federal-tax exempt, so compare on a taxable-equivalent basis. Savings bonds (I and EE) accrue or composite with inflation and reward holding to term.

Applications

▸Parking cash in T-Bills versus a money-market fund after tax
▸Choosing municipal versus corporate bonds in a high tax bracket
▸Holding I Bonds as an inflation hedge or EE Bonds for a 20-year double
▸Rolling Treasury auctions into a cash ladder

Benefits

  • •Puts discount, coupon and tax-exempt structures on one comparable basis
  • •Converts muni yields to taxable-equivalent hurdles
  • •Shows T-Bill discount versus investment (bond-equivalent) yield
  • •Separates real yield from inflation compensation on linkers

Limitations

  • •State-tax and AMT treatment varies by issue and domicile
  • •Auction prices move between announcement and settlement
  • •CPI linkage lags actual inflation prints by months
  • •Early redemption penalties (savings bonds) change realized returns

Best Practices

  • •Compare T-Bills to CDs on an after-tax, same-day-count basis
  • •Rerun muni math at your exact marginal bracket
  • •Hold savings bonds to their guarantee dates (12 months minimum, 20 years for EE doubling)
  • •Track CPI reset dates for I Bonds and TIPS

Common Misconceptions

Myth: Treasuries are risk-free in every sense
Truth: Credit risk is minimal, but price risk from rate moves and inflation risk on nominal bonds remain.
Myth: A muni always beats a corporate
Truth: Only above a break-even bracket. Below it, the taxable bond wins after tax.

Practical Tips

  • •T-Bill interest is state/local-tax exempt.
  • •Roll bills to build a cash ladder.

Common Mistakes

Comparing discount yield to a coupon
Convert to investment yield first.

Assumptions

This calculator makes the following assumptions to provide estimates:

Held to maturity; no coupon: Discount instrument.

Limitations

Be aware of these limitations when using this calculator:

Limitation: State-tax and AMT treatment varies by issue and domicile
Limitation: Auction prices move between announcement and settlement
Limitation: CPI linkage lags actual inflation prints by months
Limitation: Early redemption penalties (savings bonds) change realized returns

Frequently Asked Questions

Answers to common questions about this calculator.

Discount vs investment yield?
Discount divides by face (360 days); investment divides by price (365 days) — investment is higher and comparable.
Who uses the t-bill calculator?
It is used by investors comparing treasury bond options, by advisers checking a quote before a client commits, and by planners sizing contributions for a goal. It sits in the Treasury & Government group of the Bonds & Fixed Income section of Atlascalcs.
How accurate is the t-bill calculator?
Every figure follows directly from the inputs using standard bond mathematics, so it is accurate to the quality of the values you enter. Dealer quotes round to cents and apply day-count conventions, so expect pennies of difference on accrued interest and settlement figures.
How current are the yields used here?
The calculator uses the figures you enter, so update the yield to your dealer quote or auction result. Market yields move intraday; ratio and tax thresholds follow the conventions in the references.
Does rounding change the results?
All math runs at full precision and rounds only for display. Dealers round to cents and apply day-count conventions, so expect pennies of difference on accrued interest.
Should I compare coupons or yields?
Always yields (YTM for total return, current yield for income). Two bonds with different coupons price identically at the same YTM.
What should I have ready before buying?
Face, coupon, maturity, frequency, price or yield, settlement date, tax bracket and any call or conversion terms. With those, every figure here ties to a quote.

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Related Guides

Deepen your understanding with these educational resources.

Glossary

Technical terms used in mortgage calculations explained in plain language.

T-Bill
U.S. Treasury bill (≤1 year) sold at a discount with no coupons.
Par (Face) Value
Principal repaid at maturity, usually $1,000 per bond.

Authoritative References

Trusted sources and standards referenced by this calculator.

Applicable Standards

Present-value pricing with periodic compounding at the quoted yieldYTM solved numerically (bisection) to full precision; display rounded onlyT-Bill bank discount on 360 days; investment yield on 365 daysMoney rounded for display only; all calculations run at full precision

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Page Information

Last Updated:

2026-09-22

Version:

2.0.0

License:

Free to use for educational and professional purposes.