PCB Trace Width Calculator

Estimate PCB trace width using current, temperature rise, and copper thickness based on IPC-2221 (external layers).

A
mA

1 oz/ft² (1.378 mils)
2 oz/ft² (2.756 mils)
3 oz/ft² (4.134 mils)
0.5 oz/ft² (0.689 mils)


function calculatePCBTraceWidth() {
const current = parseFloat(document.getElementById(“current”).value) * parseFloat(document.getElementById(“currentUnit”).value);
const tempRise = parseFloat(document.getElementById(“tempRise”).value);
const thickness_mils = parseFloat(document.getElementById(“copperThickness”).value);

if (isNaN(current) || current <= 0 || isNaN(tempRise) || tempRise <= 0) {
document.getElementById("traceResult").innerHTML = "⚠️ Please enter valid values for current and temperature rise.";
return;
}

// IPC-2221 constants for EXTERNAL layers
const k = 0.048;
const b = 0.44;
const c = 0.725;

// Cross-sectional area in mils^2
const area_mils2 = Math.pow(current / (k * Math.pow(tempRise, b)), 1 / c);

// Width in mils = Area / Thickness
const width_mils = area_mils2 / thickness_mils;

// Convert mils to mm
const width_mm = width_mils * 0.0254;

document.getElementById("traceResult").innerHTML = `
📏 Required Trace Width:
${width_mm.toFixed(3)} mm or
${width_mils.toFixed(2)} mils
`;
}

function clearTraceFields() {
document.getElementById(“current”).value = “”;
document.getElementById(“tempRise”).value = “”;
document.getElementById(“traceResult”).innerHTML = “”;
}

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