PCB Unit Converter

Length Conversion

Convert between mil, mm, inch, and micron

0.0254

Copper Weight

Convert between oz/ft² and thickness

35.0018

Area Conversion

Convert between square units

0.00064516

Temperature

Convert between Celsius and Fahrenheit

77

Fahrenheit (°F)

Quick Reference

Copper Weight to Thickness

oz/ft²	Micron	Mil
1/3 oz	9 μm	0.35 mil
1/2 oz	17 μm	0.7 mil
1 oz	35 μm	1.4 mil
2 oz	70 μm	2.8 mil
3 oz	105 μm	4.2 mil

Common Conversions

1 mil0.0254 mm = 25.4 μm

1 mm39.37 mil

1 inch25.4 mm = 1000 mil

1 oz copper35 μm = 1.4 mil thickness

Unit Tips

Mil (thousandths of an inch) is commonly used in US PCB specifications
Metric (mm) is standard in most international specifications
Copper weight in oz/ft² is an industry-standard way to specify copper thickness
1 oz copper ≈ 35 μm thickness is a fundamental PCB conversion
When in doubt, check your manufacturer's preferred unit system

Frequently Asked Questions

What is a mil in PCB design?

A mil is 1/1000 of an inch (0.001 inch or 0.0254 mm). It's commonly used in the US PCB industry for trace widths, spacing, and hole sizes. For example, a '6 mil trace' means a trace that is 0.006 inches or about 0.15 mm wide.

How do I convert oz copper to thickness?

Copper weight in oz/ft² converts to thickness: 1 oz = 35 μm (1.4 mil), 2 oz = 70 μm (2.8 mil), 0.5 oz = 17 μm (0.7 mil). This is based on the weight of copper per square foot of the PCB surface.

Should I use mil or mm for my design?

It depends on your manufacturer and design tools. US manufacturers often prefer mil, while Asian and European manufacturers may prefer mm. Most modern CAD tools support both. The key is consistency - pick one system and stick with it throughout your design.

What is the standard copper weight for flex PCB?

Standard copper weights for flex PCB are 1/2 oz (17 μm) and 1 oz (35 μm). Thinner copper (1/3 oz) is used for tighter bends, while thicker copper (2 oz) is used for high-current applications. Thinner copper allows for smaller bend radii.

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