{
  "id": "pcb-trace-width",
  "slug": "pcb-trace-width-calculator",
  "url": "https://electronics.tools/tools/pcb-trace-width-calculator/",
  "name": "PCB Trace Width Calculator",
  "group": "pcb-wire",
  "summary": "A = (I / (k·ΔT^0.44))^(1/0.725). 1 A, 1 oz, 10 °C external is 11.83 mil (0.3004 mm).",
  "formulas": [
    {
      "id": "area",
      "label": "IPC-2221A §6.2 area",
      "plain": "A = (I / (k · ΔT^0.44))^(1/0.725)",
      "mathml": "<math display=\"block\" xmlns=\"http://www.w3.org/1998/Math/MathML\" aria-label=\"A = (I / (k · ΔT^0.44))^(1/0.725)\"><mrow><mi>A</mi><mo>=</mo><mrow><mo>(</mo><mrow><mfrac><mi>I</mi><mrow><mi>k</mi><mi>Δ</mi><msup><mi>T</mi><mn>0.44</mn></msup></mrow></mfrac><msup><mi>)</mi><mrow><mn>1</mn><mo>/</mo><mn>0.725</mn></mrow></msup></mrow><mo>)</mo></mrow></mrow></math>",
      "symbols": [
        "A",
        "I",
        "k",
        "ΔT"
      ],
      "sources": [
        "ipc"
      ]
    },
    {
      "id": "width",
      "label": "Width from thickness",
      "plain": "W = A / (t_oz · 1.378 mil)",
      "mathml": "<math display=\"block\" xmlns=\"http://www.w3.org/1998/Math/MathML\" aria-label=\"W = A / (t_oz · 1.378 mil)\"><mrow><mi>W</mi><mo>=</mo><mfrac><mi>A</mi><mrow><mi>t</mi><mo>×</mo><mn>1.378</mn></mrow></mfrac></mrow></math>",
      "symbols": [
        "W",
        "A"
      ],
      "sources": [
        "ipc"
      ]
    }
  ],
  "variables": [
    {
      "symbol": "I",
      "name": "Current",
      "unit": "A",
      "role": "input",
      "precision": {
        "sig": 4
      },
      "range": {
        "min": 0,
        "softMax": 35,
        "note": "Curve fit quoted around I ≤ 35 A"
      },
      "default": 1,
      "urlParam": "i"
    },
    {
      "symbol": "t",
      "name": "Copper thickness",
      "unit": "oz/ft²",
      "role": "input",
      "precision": {
        "sig": 4
      },
      "range": {
        "min": 0,
        "note": "1 oz/ft² = 1.378 mil (35 µm convention)"
      },
      "default": 1,
      "urlParam": "oz"
    },
    {
      "symbol": "ΔT",
      "name": "Temperature rise",
      "unit": "°C",
      "role": "input",
      "precision": {
        "sig": 4
      },
      "range": {
        "min": 0,
        "softMin": 10,
        "softMax": 100,
        "note": "Curve fit quoted for about 10–100 °C"
      },
      "default": 10,
      "urlParam": "dt"
    },
    {
      "symbol": "Tamb",
      "name": "Ambient temperature",
      "unit": "°C",
      "role": "input",
      "precision": {
        "sig": 4
      },
      "default": 25,
      "urlParam": "ta"
    },
    {
      "symbol": "L",
      "name": "Length",
      "unit": "mm",
      "role": "input",
      "precision": {
        "sig": 4
      },
      "range": {
        "min": 0
      },
      "default": 50,
      "urlParam": "len"
    },
    {
      "symbol": "k",
      "name": "Layer (k = 0.048 external, 0.024 internal)",
      "unit": "1",
      "role": "input",
      "precision": {
        "sig": 1
      },
      "default": "external",
      "urlParam": "layer"
    },
    {
      "symbol": "A",
      "name": "Cross-section",
      "unit": "mil²",
      "role": "output",
      "precision": {
        "sig": 4
      }
    },
    {
      "symbol": "W",
      "name": "Trace width",
      "unit": "mil",
      "role": "output",
      "precision": {
        "sig": 4
      }
    },
    {
      "symbol": "Wmm",
      "name": "Trace width",
      "unit": "mm",
      "role": "output",
      "precision": {
        "sig": 4
      }
    },
    {
      "symbol": "R",
      "name": "DC resistance at Tamb+ΔT",
      "unit": "Ω",
      "role": "output",
      "precision": {
        "sig": 4
      }
    }
  ],
  "examples": [
    {
      "id": "1a-1oz-10c-ext-50mm",
      "title": "1 A, 1 oz, 10 °C external, 50 mm",
      "input": [
        {
          "symbol": "I",
          "value": 1,
          "unit": "A",
          "display": "1 A"
        },
        {
          "symbol": "t",
          "value": 1,
          "unit": "oz/ft²",
          "display": "1 oz/ft²"
        },
        {
          "symbol": "ΔT",
          "value": 10,
          "unit": "°C",
          "display": "10 °C"
        },
        {
          "symbol": "Tamb",
          "value": 25,
          "unit": "°C",
          "display": "25 °C"
        },
        {
          "symbol": "L",
          "value": 50,
          "unit": "mm",
          "display": "50 mm"
        },
        {
          "symbol": "k",
          "value": "external",
          "unit": "1",
          "display": "external"
        }
      ],
      "output": [
        {
          "symbol": "A",
          "value": 16.296001347209486,
          "unit": "mil²",
          "display": "16.3 mil²"
        },
        {
          "symbol": "W",
          "value": 11.825835520471326,
          "unit": "mil",
          "display": "11.83 mil"
        },
        {
          "symbol": "Wmm",
          "value": 0.3003762222199717,
          "unit": "mm",
          "display": "0.3004 mm"
        },
        {
          "symbol": "R",
          "value": 0.08402555077080005,
          "unit": "Ω",
          "display": "84.03 mΩ"
        }
      ],
      "computedBy": "pcbTraceWidth"
    },
    {
      "id": "1a-int",
      "title": "Same, internal layer",
      "input": [
        {
          "symbol": "I",
          "value": 1,
          "unit": "A",
          "display": "1 A"
        },
        {
          "symbol": "t",
          "value": 1,
          "unit": "oz/ft²",
          "display": "1 oz/ft²"
        },
        {
          "symbol": "ΔT",
          "value": 10,
          "unit": "°C",
          "display": "10 °C"
        },
        {
          "symbol": "k",
          "value": "internal",
          "unit": "1",
          "display": "internal"
        }
      ],
      "output": [
        {
          "symbol": "W",
          "value": 30.764199672661377,
          "unit": "mil",
          "display": "30.76 mil"
        },
        {
          "symbol": "Wmm",
          "value": 0.781410671685599,
          "unit": "mm",
          "display": "0.7814 mm"
        }
      ],
      "computedBy": "pcbTraceWidth"
    }
  ],
  "sources": [
    {
      "title": "IPC-2221A Generic Standard on Printed Board Design §6.2 (current-carrying capacity)",
      "url": "https://www.ipc.org/system/files/technical_resource/E38%26S16_01%20-%20IPC-2221.pdf",
      "retrieved": "2026-11-02",
      "standard": "IPC-2221A"
    }
  ],
  "datePublished": "2026-11-02T00:00:00+08:00",
  "dateModified": "2026-11-02T00:00:00+08:00",
  "author": {
    "name": "Jasper",
    "url": "https://electronics.tools/about/#jasper"
  },
  "relatedTools": [
    "https://electronics.tools/tools/awg-wire-size-calculator/",
    "https://electronics.tools/tools/ohms-law-calculator/"
  ]
}