Copper Weight to Thickness Calculator

In PCB design and electronics manufacturing, copper weight (measured in oz/ft²) is the standard way to specify how thick the copper layer on a board should be — but working with the actual physical thickness requires a conversion. Enter a copper weight (oz/ft²) or a thickness in mils and select your conversion direction to get results in mils, microns (μm), and inches, plus the equivalent copper weight. Also try the find Via Impedance with Via Impedance Calculator.

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Thickness

Copper Weight

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What is the standard conversion formula for copper weight to thickness?

The standard formula is: Thickness (mils) = Weight (oz/ft²) × 1.37. This means 1 oz/ft² of copper equals 1.37 mils thickness, or 0.00137 inches. See also our Coplanar Waveguide Calculator.

Why is copper thickness important in PCB design?

Copper thickness affects current carrying capacity and trace impedance. Thicker copper can handle more current but may affect impedance calculations in high-speed digital and RF circuits.

What are the most common copper weights used in PCBs?

The most common copper weights are 0.5 oz (0.7 mils), 1 oz (1.4 mils), and 2 oz (2.8 mils). Heavy copper applications may use 3 oz or higher. You might also find our PCB Impedance Calculator useful.

How do I convert mils to micrometers?

To convert mils to micrometers (μm), multiply by 25.4. For example, 1.4 mils equals 35.6 μm. This conversion is useful for international specifications.

What is the difference between copper weight and copper thickness?

Copper weight (oz/ft²) measures mass per unit area, while thickness (mils/μm) measures physical dimension. Both describe the same copper layer but in different units.

Can I calculate trace current capacity from copper thickness?

Yes, trace current capacity depends on copper thickness and trace width. Thicker copper allows higher current density, typically following IPC-2221 standards for temperature rise calculations.