{
  "slug": "pipe-flow-rate",
  "title": "Pipe Flow Rate Calculator",
  "heading": "Pipe Flow Rate & Velocity Calculator",
  "category": "other",
  "url": "https://www.revenuelab.fyi/toolbox/pipe-flow-rate",
  "summary": "GPM, velocity, and fill time for a given pipe size.",
  "description": "Keep water velocity under about 7 ft/s in copper to avoid erosion and noise. Doubling pipe diameter roughly quadruples capacity at the same velocity.",
  "formula": "GPM = area (sq ft) × velocity (ft/s) × 448.8.",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=pipe-flow-rate",
  "inputs": [
    {
      "id": "diameter",
      "label": "Inside diameter",
      "kind": "number",
      "hint": null,
      "default": 1,
      "unit": "in",
      "min": 0.125,
      "max": null
    },
    {
      "id": "velocity",
      "label": "Flow velocity",
      "kind": "number",
      "hint": null,
      "default": 5,
      "unit": "ft/s",
      "min": 0.1,
      "max": 20
    },
    {
      "id": "volume",
      "label": "Volume to fill",
      "kind": "number",
      "hint": null,
      "default": 500,
      "unit": "gal",
      "min": 0,
      "max": null
    }
  ],
  "outputs": [
    {
      "id": "gpm",
      "label": "Flow rate (gal/min)",
      "format": "decimal",
      "hint": null,
      "primary": true
    },
    {
      "id": "gph",
      "label": "Gallons per hour",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "lpm",
      "label": "Liters per minute",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "fillMin",
      "label": "Minutes to fill volume",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "areaSqIn",
      "label": "Pipe area (sq in)",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "cfs",
      "label": "Cubic feet per second",
      "format": "decimal",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Inside diameter: 1 in",
      "Flow velocity: 5 ft/s",
      "Volume to fill: 500 gal"
    ],
    "outputs": [
      "Flow rate (gal/min): 12.24",
      "Gallons per hour: 734",
      "Liters per minute: 46.3",
      "Minutes to fill volume: 40.9",
      "Pipe area (sq in): 0.785",
      "Cubic feet per second: 0.0273"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter inside diameter (in).",
      "Enter flow velocity (ft/s).",
      "Enter volume to fill (gal).",
      "Read your flow rate (gal/min) 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": {
        "diameter": 0.6,
        "velocity": 3,
        "volume": 300
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "diameter": 1,
        "velocity": 5,
        "volume": 500
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "diameter": 1.6,
        "velocity": 8,
        "volume": 800
      }
    }
  ],
  "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 pipe flow rate & velocity calculator work?",
      "a": "Keep water velocity under about 7 ft/s in copper to avoid erosion and noise. Doubling pipe diameter roughly quadruples capacity at the same velocity. The underlying maths is: GPM = area (sq ft) × velocity (ft/s) × 448.8."
    },
    {
      "q": "What do I need to enter?",
      "a": "3 values: inside diameter, flow velocity, and volume to fill. 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 flow rate (gal/min) 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/sprinkler-run-time",
    "https://www.revenuelab.fyi/toolbox/pump-horsepower"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Pipe Flow Rate Calculator (https://www.revenuelab.fyi/toolbox/pipe-flow-rate)"
}