PCB Copper Weight Calculator

This tool converts copper weight (in ounces per square foot) to physical thickness (in micrometers or mils), calculates DC resistance of a trace based on dimensions and temperature, and estimates total copper mass for a given board area. All results are derived from standard IPC-2221 material constants and resistivity models.

Copper weight directly affects current-carrying capacity, thermal performance, impedance control, and etch yield. Heavier copper (e.g., 2 oz or more) is used for high-power traces, ground planes, and thermal management, while standard 1 oz is typical for signal routing.

“Oz” refers to ounces per square foot — a unit of surface density, not mass per volume. 1 oz/ft² equals ~35 µm (1.4 mils) thickness for pure copper. The calculator uses this standardized conversion, assuming 100% copper density (8.96 g/cm³).

Standard copper weights range from 0.5 oz (17.5 µm) to 6 oz (210 µm); common trace widths are 0.1–10 mm; and lengths vary widely — but inputs should reflect actual net geometry (e.g., longest path for worst-case resistance). For plane weight estimation, board area should match the copper layer’s active coverage.

The calculator applies the temperature coefficient of copper (α = 0.00393/°C) to adjust resistivity from the reference value at 20°C. Higher temperatures increase resistance — critical for power integrity and thermal derating in high-current designs.

Yes — copper weight is layer-agnostic, and the calculator treats all layers identically. However, note that outer-layer copper may be slightly thicker due to plating (e.g., 1 oz base + 0.5 oz plating ≈ 1.5 oz finished), so input the final *finished* copper weight for accuracy.

Verify units: trace width and length must be in millimeters (mm), and ensure you’re using finished copper weight—not base foil weight. Also check for unintended scaling errors (e.g., entering cm instead of mm) or excessive temperature values skewing resistivity.

The mass calculation assumes uniform copper coverage over the specified board area and ideal density. It excludes features like vias, pads, or etched gaps — so treat it as a first-order estimate for material costing or thermal mass modeling. For precision, use CAD-derived copper area data.

No — this calculator computes only DC (or low-frequency) resistance using bulk resistivity. For RF/microwave designs above ~1 MHz, skin depth reduces effective conduction area; use dedicated AC resistance or field solvers for accurate high-frequency loss estimation.

They describe the same physical property but in different units: weight (oz/ft²) is a manufacturing specification tied to foil roll density; thickness (µm/mils) is the resulting dimension after lamination and etching. The calculator bridges these conventions using industry-standard conversion factors.