{
  "slug": "wire-gauge",
  "title": "Wire Gauge & Voltage Drop Calculator",
  "heading": "Wire Size & Voltage Drop Calculator",
  "category": "other",
  "url": "https://www.revenuelab.fyi/toolbox/wire-gauge",
  "summary": "Voltage drop over a run and the gauge you actually need.",
  "description": "Keep voltage drop under 3% on branch circuits. Long runs to a shed or well pump are where undersized copper quietly costs you performance.",
  "formula": "Vdrop = 2 × K × I × L ÷ circular mils (K ≈ 12.9 for copper).",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=wire-gauge",
  "inputs": [
    {
      "id": "amps",
      "label": "Load current",
      "kind": "number",
      "hint": null,
      "default": 20,
      "unit": "A",
      "min": 0.5,
      "max": null
    },
    {
      "id": "volts",
      "label": "System voltage",
      "kind": "number",
      "hint": null,
      "default": 120,
      "unit": "V",
      "min": 12,
      "max": null
    },
    {
      "id": "length",
      "label": "One-way run length",
      "kind": "number",
      "hint": null,
      "default": 100,
      "unit": "ft",
      "min": 1,
      "max": null
    },
    {
      "id": "awg",
      "label": "Wire gauge (AWG)",
      "kind": "number",
      "hint": null,
      "default": 12,
      "unit": null,
      "min": 0,
      "max": 14
    },
    {
      "id": "material",
      "label": "Conductor",
      "kind": "select",
      "hint": null,
      "default": "cu",
      "options": [
        {
          "value": "cu",
          "label": "Copper"
        },
        {
          "value": "al",
          "label": "Aluminum"
        }
      ]
    }
  ],
  "outputs": [
    {
      "id": "pct",
      "label": "Voltage drop (%)",
      "format": "decimal",
      "hint": null,
      "primary": true
    },
    {
      "id": "drop",
      "label": "Voltage drop (V)",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "endVolts",
      "label": "Voltage at load",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "recAwg",
      "label": "Recommended AWG for 3% drop",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "watts",
      "label": "Power lost in wire (W)",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "needMils",
      "label": "Required circular mils",
      "format": "decimal",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Load current: 20 A",
      "System voltage: 120 V",
      "One-way run length: 100 ft",
      "Wire gauge (AWG): 12",
      "Conductor: Copper"
    ],
    "outputs": [
      "Voltage drop (%): 6.58",
      "Voltage drop (V): 7.9",
      "Voltage at load: 112.1",
      "Recommended AWG for 3% drop: 8",
      "Power lost in wire (W): 158",
      "Required circular mils: 14,333"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter load current (A).",
      "Enter system voltage (V).",
      "Enter one-way run length (ft).",
      "Enter wire gauge (awg).",
      "Enter conductor.",
      "Read your voltage drop (%) 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": {
        "amps": 12,
        "volts": 72,
        "length": 60,
        "awg": 7,
        "material": "cu"
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "amps": 20,
        "volts": 120,
        "length": 100,
        "awg": 12,
        "material": "cu"
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "amps": 32,
        "volts": 192,
        "length": 160,
        "awg": 14,
        "material": "cu"
      }
    }
  ],
  "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 wire size & voltage drop calculator work?",
      "a": "Keep voltage drop under 3% on branch circuits. Long runs to a shed or well pump are where undersized copper quietly costs you performance. The underlying maths is: Vdrop = 2 × K × I × L ÷ circular mils (K ≈ 12.9 for copper)."
    },
    {
      "q": "What do I need to enter?",
      "a": "5 values: load current, system voltage, one-way run length, wire gauge (awg), and conductor. 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 voltage drop (%) 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/generator-sizing",
    "https://www.revenuelab.fyi/toolbox/electricity-cost"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Wire Gauge & Voltage Drop Calculator (https://www.revenuelab.fyi/toolbox/wire-gauge)"
}