T-Bill Calculator
Treasury bills are sold at a discount and pay face value at maturity — the difference is your interest, free of state and local tax. Example: a $10,000 26-week bill at $98.50 per $100 earns $150 in about six months, an annualized yield of roughly 3%.
How to use this calculator
- Enter price you pay (per $100 face).
- Enter face value at maturity.
- Enter days to maturity.
- Your results appear instantly below and update as you change the numbers.
How this calculator works
You buy a T-bill for less than its face value; at maturity the Treasury pays you the full face value. Worked example: a $10,000 bill bought at 98.50 with 182 days to maturity costs $9,850 and pays $10,000 — a $150 gain, quoted as a 2.97% bank discount yield and a 3.05% investment yield. The calculator derives the discount and shows both yields: the bank discount yield (360-day year, on face value — how the Treasury quotes auctions) and the investment yield (365-day year, on what you paid — the number comparable to CDs and bonds).
Frequently asked questions
Are T-bill yields state-taxable?
Interest on Treasury bills is exempt from state and local income tax — only federal tax applies. That makes the after-tax yield higher than a CD at the same rate in most states.
What is the minimum to buy a T-bill?
$100 via TreasuryDirect. You can also buy through a brokerage, where the minimum is often $1,000.
How are T-bill yields quoted?
Auction results quote the bank discount yield, which understates the return you actually earn. The investment yield (also called bond equivalent yield) is the comparable number — it is always slightly higher.
What happens at maturity?
The Treasury repays the full face value to your TreasuryDirect or brokerage account. You can let it sit, or use TreasuryDirect's reinvest option to roll the proceeds into a new bill at the next auction — the standard way to build a T-bill ladder.
Disclaimer: Results are estimates for general information only and do not constitute financial, tax, or legal advice. Figures reflect 2026 rules and may change. Always confirm current limits and consult a qualified professional before making decisions. Official figures: IRS.gov · 2026 limits per IRS tax inflation adjustments.