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Treasury Bill (T-Bill) Calculator

Calculate your T-bill purchase price, discount amount, and annualized yield for any term from 4 weeks to 52 weeks.

Updated July 2026 · Editorial standards

Your purchase price
$9,867.29
Discount (your profit)
$132.71
Coupon-equivalent yield
5.395%
Face value$10,000.00Annualized return5.395%Term return1.345%

T-Bill Details

$
%

Key figures

Purchase price
$9,867.29
Discount (profit)
$132.71
Coupon-equiv. yield
5.395%
Annualized return
5.395%

A 13-week (91 days) T-bill with 5.25% discount rate: you pay $9,867.29 and receive $10,000.00 at maturity — a $132.71 gain.The coupon-equivalent yield (5.395%) is higher than the discount rate because it accounts for the smaller amount you actually invested.

Purchase price
$9,867.29
By KalkWiseVerified against official sources Updated July 2026

What is the treasury bill (t-bill) calculator?

In short

A $10,000 face-value 13-week T-bill at a 5.25% discount rate costs $9,867.08 at purchase. You earn $132.92 in 91 days — a coupon-equivalent yield of 5.42% annualized. T-bills are backed by the U.S. government and are state-tax exempt.

This T-bill calculator converts a Treasury bill's discount rate into purchase price, dollar profit (discount amount), coupon-equivalent yield, and annualized return. It works for all standard terms: 4-week (28 days), 13-week (91 days), 26-week (182 days), and 52-week (364 days).

How to use this calculator

  1. 1Enter the face value (the amount you receive at maturity — minimum $100).
  2. 2Enter the discount rate as shown at auction (e.g., 5.25%).
  3. 3Select the term: 4-week, 13-week, 26-week, or 52-week.
  4. 4Read your purchase price and coupon-equivalent yield to compare against CDs, HYSA, or money-market rates.

The formula

P=F×(1−d×t360)
CEY=F−PP×365t
T-bills use a 360-day bank discount convention. Purchase price = F × (1 − d × t/360). The discount you earn = F − P. Coupon-equivalent yield (CEY) uses 365 days and the actual invested amount: CEY = (F − P)/P × 365/t. CEY is always higher than the discount rate because the denominator is the lower purchase price, not face value.
F
— Face value (maturity value)
d
— Bank discount rate (annual)
t
— Days to maturity
P
— Purchase price
CEY
— Coupon-equivalent yield

Worked example

The scenario

$10,000 face value, 5.25% discount rate, 91-day (13-week) term.

gives

The result

Purchase price = $10,000 × (1 − 0.0525 × 91/360) = $10,000 × 0.986708 = $9,867.08. Discount earned = $132.92. CEY = ($132.92 / $9,867.08) × (365/91) = 5.418%. You invest $9,867.08 and receive $10,000 in 91 days.

Common use cases

  • Comparing T-bill yields against high-yield savings accounts and CDs for short-term cash.
  • Calculating exact return before purchasing at TreasuryDirect.gov or through a brokerage.
  • Understanding why the coupon-equivalent yield is higher than the quoted discount rate.
  • Evaluating T-bills as a state-tax-exempt alternative to savings accounts.

Limitations & assumptions

  • Auction discount rates change weekly — the rate shown is the rate at the specific auction you buy.
  • Secondary-market T-bill prices differ from auction prices; this calculator uses the bank discount formula for new issues.
  • T-bills are exempt from state and local income tax, but subject to federal tax — not shown here.
  • Bills bought through a broker may include a small markup; TreasuryDirect has no markup but fewer automation options.

Frequently asked questions

The discount rate (e.g., 5.25%) is calculated on face value using a 360-day year — it's the convention used at U.S. Treasury auctions. The coupon-equivalent yield (5.42% for a 91-day bill at 5.25%) uses the actual purchase price and a 365-day year, making it directly comparable to CD or savings account APYs. CEY is always higher than the discount rate.

Disclaimer: KalkWise calculators are provided for general informational and educational purposes only and do not constitute financial, investment, tax, or legal advice. Results are estimates based on the figures you enter and the assumptions described above. Actual outcomes will vary. Consult a qualified professional before making financial decisions.