{
  "slug": "project-buffer-estimator",
  "title": "Project Buffer Estimator",
  "heading": "Project Buffer Estimator",
  "category": "other",
  "url": "https://www.revenuelab.fyi/toolbox/project-buffer-estimator",
  "summary": "How much schedule padding a project actually needs.",
  "description": "Estimates slip. This applies an optimism factor and a risk buffer to your raw estimate so the date you promise is a date you can hit.",
  "formula": "Committed = estimate × (1 + overrun) × (1 + risk).",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=project-buffer-estimator",
  "inputs": [
    {
      "id": "estimate",
      "label": "Raw estimate",
      "kind": "number",
      "hint": null,
      "default": 20,
      "unit": "days",
      "min": 1,
      "max": null
    },
    {
      "id": "optimism",
      "label": "Historical overrun",
      "kind": "number",
      "hint": null,
      "default": 30,
      "unit": "%",
      "min": 0,
      "max": 200
    },
    {
      "id": "risk",
      "label": "Risk buffer",
      "kind": "number",
      "hint": null,
      "default": 15,
      "unit": "%",
      "min": 0,
      "max": 100
    }
  ],
  "outputs": [
    {
      "id": "total",
      "label": "Commit to",
      "format": "decimal",
      "hint": null,
      "primary": true
    },
    {
      "id": "adjusted",
      "label": "Overrun-adjusted days",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "buffer",
      "label": "Buffer added",
      "format": "decimal",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Raw estimate: 20 days",
      "Historical overrun: 30 %",
      "Risk buffer: 15 %"
    ],
    "outputs": [
      "Commit to: 29.9",
      "Overrun-adjusted days: 26",
      "Buffer added: 9.9"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter raw estimate (days).",
      "Enter historical overrun (%).",
      "Enter risk buffer (%).",
      "Read your commit to 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": {
        "estimate": 12,
        "optimism": 20,
        "risk": 10
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "estimate": 20,
        "optimism": 30,
        "risk": 15
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "estimate": 32,
        "optimism": 50,
        "risk": 25
      }
    }
  ],
  "limitations": [
    "Estimates assume standard, average conditions — local rules, pricing, and materials vary.",
    "Results are rounded for readability; add a buffer before ordering, booking, or committing.",
    "Double-check anything with a real cost attached against a local quote."
  ],
  "faq": [
    {
      "q": "How does the project buffer estimator work?",
      "a": "Estimates slip. This applies an optimism factor and a risk buffer to your raw estimate so the date you promise is a date you can hit. The underlying maths is: Committed = estimate × (1 + overrun) × (1 + risk)."
    },
    {
      "q": "What do I need to enter?",
      "a": "3 values: raw estimate, historical overrun, and risk buffer. 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 commit to result mean?",
      "a": "It is returned as a decimal number 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. Estimates assume standard, average conditions — local rules, pricing, and materials vary."
    },
    {
      "q": "Who is this tool for?",
      "a": "It's built for anyone doing everyday planning maths — a quick estimate that would otherwise need four browser tabs and a calculator app."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/scope-creep-cost",
    "https://www.revenuelab.fyi/toolbox/freelance-utilization-rate"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Project Buffer Estimator (https://www.revenuelab.fyi/toolbox/project-buffer-estimator)"
}