Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Investment (coupon-equivalent) yield
4.511%
Bank discount yield
4.352%
Interest earned at maturity
$220.00
After federal tax yield
3.429%
Taxable-equivalent yield vs a CD
3.647%
After-tax interest
$167.20
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How to use this
- 1Enter face value ($).
- 2Enter purchase price ($).
- 3Enter days to maturity.
- 4Enter federal tax rate (%).
- 5Enter state tax rate (%).
- 6Read your investment (coupon-equivalent) yield on the right — it updates as you type.
- 7Hit Share to keep the scenario or send it to someone.
About this calculator
T-bills are sold at a discount and mature at face value — there is no coupon. Their interest is exempt from state and local income tax, which raises the effective yield in high-tax states.
Worked example
Using the values the calculator loads with:
Inputs
- Face value: 10000 $
- Purchase price: 9780 $
- Days to maturity: 182
- Federal tax rate: 24 %
- State tax rate: 6 %
Results
- Investment (coupon-equivalent) yield: 4.511%
- Bank discount yield: 4.352%
- Interest earned at maturity: $220.00
- After federal tax yield: 3.429%
- Taxable-equivalent yield vs a CD: 3.647%
- After-tax interest: $167.20
What each field means
Inputs
- Face value ($)
- The face value used in the calculation, measured in $. Starts at 10000 $ so you have a working example on load.
- Purchase price ($)
- The purchase price used in the calculation, measured in $. Starts at 9780 $ so you have a working example on load.
- Days to maturity
- The days to maturity used in the calculation. Starts at 182 so you have a working example on load. Accepted range: 1–365.
- Federal tax rate (%)
- The federal tax rate used in the calculation, measured in %. Starts at 24 % so you have a working example on load. Accepted range: 0–50 %.
- State tax rate (%)
- The state tax rate used in the calculation, measured in %. Starts at 6 % so you have a working example on load. Accepted range: 0–15 %.
Results
- Investment (coupon-equivalent) yield
- Returned as a percentage and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Bank discount yield
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Interest earned at maturity
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- After federal tax yield
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Taxable-equivalent yield vs a CD
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- After-tax interest
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the t-bill yield calculator work?
T-bills are sold at a discount and mature at face value — there is no coupon. Their interest is exempt from state and local income tax, which raises the effective yield in high-tax states. The underlying maths is: Investment yield = (Face − Price) ÷ Price × (365 ÷ Days) × 100.
What do I need to enter?
5 values: face value, purchase price, days to maturity, federal tax rate, and state tax rate. Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the investment (coupon-equivalent) yield result mean?
It is returned as a percentage and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds.
Is this calculator free, and do I need an account?
Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser.
How accurate is the result?
It applies the standard formula exactly, so the arithmetic is precise. Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
Who is this tool for?
It's built for anyone comparing money scenarios before committing — budgeting a payment, sanity-checking a quote, or seeing what a change in rate or term actually costs.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Treasury Bill Yield Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/treasury-bill-yield
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/treasury-bill-yield" target="_blank" rel="noopener">Treasury Bill Yield Calculator — RevenueLab</a> (2026).</p>
Source: [Treasury Bill Yield Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/treasury-bill-yield) (2026).