Copper Weight to Thickness

Formula

Description

PCB copper thickness is traditionally specified in ounces per square foot (oz/ft²). One ounce of copper spread over one square foot gives a thickness of approximately 35 µm (1.37 mils). This is the standard unit used by PCB manufacturers worldwide. Common weights are 0.5 oz (17.5 µm), 1 oz (35 µm), and 2 oz (70 µm). Heavier copper (3-6 oz) is used for high-current power circuits. The result is in meters (base SI unit); use the unit selector to view in mm or µm.

Variables

• t — Copper thickness (m, display in µm)
• oz — Copper weight in oz/ft²

Practical Notes

Standard PCB copper weights: 0.5 oz (17.5 µm) for HDI and fine-pitch, 1 oz (35 µm) most common default, 2 oz (70 µm) for power circuits, 3 oz (105 µm) and higher for high-current applications. Plating adds additional copper: typical via plating is 20-25 µm. The minimum trace width for a given current depends directly on copper thickness — thicker copper allows narrower traces for the same current capacity.