{
  "slug": "treasury-bill-yield",
  "title": "Treasury Bill Yield Calculator",
  "heading": "T-Bill Yield Calculator",
  "category": "financial",
  "url": "https://www.revenuelab.fyi/toolbox/treasury-bill-yield",
  "summary": "Discount yield, investment yield, and after-tax return on T-bills.",
  "description": "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.",
  "formula": "Investment yield = (Face − Price) ÷ Price × (365 ÷ Days) × 100.",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=treasury-bill-yield",
  "inputs": [
    {
      "id": "face",
      "label": "Face value",
      "kind": "number",
      "hint": null,
      "default": 10000,
      "unit": "$",
      "min": 100,
      "max": null
    },
    {
      "id": "price",
      "label": "Purchase price",
      "kind": "number",
      "hint": null,
      "default": 9780,
      "unit": "$",
      "min": 1,
      "max": null
    },
    {
      "id": "days",
      "label": "Days to maturity",
      "kind": "number",
      "hint": null,
      "default": 182,
      "unit": null,
      "min": 1,
      "max": 365
    },
    {
      "id": "fed",
      "label": "Federal tax rate",
      "kind": "number",
      "hint": null,
      "default": 24,
      "unit": "%",
      "min": 0,
      "max": 50
    },
    {
      "id": "state",
      "label": "State tax rate",
      "kind": "number",
      "hint": null,
      "default": 6,
      "unit": "%",
      "min": 0,
      "max": 15
    }
  ],
  "outputs": [
    {
      "id": "invYield",
      "label": "Investment (coupon-equivalent) yield",
      "format": "percent",
      "hint": null,
      "primary": true
    },
    {
      "id": "discount",
      "label": "Bank discount yield",
      "format": "percent",
      "hint": null,
      "primary": false
    },
    {
      "id": "interest",
      "label": "Interest earned at maturity",
      "format": "currency",
      "hint": null,
      "primary": false
    },
    {
      "id": "afterTax",
      "label": "After federal tax yield",
      "format": "percent",
      "hint": null,
      "primary": false
    },
    {
      "id": "equivalent",
      "label": "Taxable-equivalent yield vs a CD",
      "format": "percent",
      "hint": null,
      "primary": false
    },
    {
      "id": "netInterest",
      "label": "After-tax interest",
      "format": "currency",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Face value: 10000 $",
      "Purchase price: 9780 $",
      "Days to maturity: 182",
      "Federal tax rate: 24 %",
      "State tax rate: 6 %"
    ],
    "outputs": [
      "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: $167.20"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter face value ($).",
      "Enter purchase price ($).",
      "Enter days to maturity.",
      "Enter federal tax rate (%).",
      "Enter state tax rate (%).",
      "Read your investment (coupon-equivalent) yield on the right — it updates as you type.",
      "Hit Share to keep the scenario or send it to someone."
    ]
  },
  "scenarios": [
    {
      "name": "Conservative",
      "description": "Lower-end numbers — what if things land soft?",
      "values": {
        "face": 6000,
        "price": 5870,
        "days": 109,
        "fed": 14,
        "state": 3.5999999999999996
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "face": 10000,
        "price": 9780,
        "days": 182,
        "fed": 24,
        "state": 6
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "face": 16000,
        "price": 15650,
        "days": 291,
        "fed": 38,
        "state": 9.600000000000001
      }
    }
  ],
  "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."
  ],
  "faq": [
    {
      "q": "How does the t-bill yield calculator work?",
      "a": "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."
    },
    {
      "q": "What do I need to enter?",
      "a": "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."
    },
    {
      "q": "What does the investment (coupon-equivalent) yield result mean?",
      "a": "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."
    },
    {
      "q": "Is this calculator free, and do I need an account?",
      "a": "Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser."
    },
    {
      "q": "How accurate is the result?",
      "a": "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."
    },
    {
      "q": "Who is this tool for?",
      "a": "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."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/bond-yield-to-maturity",
    "https://www.revenuelab.fyi/toolbox/cd-ladder"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Treasury Bill Yield Calculator (https://www.revenuelab.fyi/toolbox/treasury-bill-yield)"
}