PCB Copper Weight: 0.5oz vs 1oz vs 2oz

Choosing the right copper weight for your PCB is one of those decisions that seems simple until you realize how much it affects everything else—trace width, current capacity, cost, manufacturability, and even impedance. Whether you're designing a low-power IoT sensor or a beefy motor controller, understanding the trade-offs between 0.5oz, 1oz, and 2oz copper is essential.

This guide breaks down everything you need to know about copper weight selection, with real numbers and practical recommendations. No fluff, just facts.

What Is Copper Weight (And Why oz/ft²)?

Copper weight is measured in ounces per square foot (oz/ft²)—a unit that confuses newcomers because it describes weight rather than thickness. The logic is simple: take 1 square foot of copper, weigh it, and that's your copper weight.

This system dates back to early PCB manufacturing when copper foil was sold by weight. Today, the convention persists even though designers care about thickness, not weight. Here's the conversion you'll actually use:

Current Capacity: The Main Event

The biggest reason to choose heavier copper is current capacity. Thicker copper has a larger cross-sectional area, which means more room for electrons to flow and better heat dissipation.

Notice the pattern? Doubling the copper weight roughly halves the required trace width. For high-current applications, the difference between 0.5oz and 2oz copper can mean the difference between a feasible design and an impossible routing nightmare.

Use our Trace Width Calculator to find exact values for your specific current, temperature rise, and copper weight combination.

0.5oz Copper: The Lightweight Champion

1oz Copper: The Industry Standard

If you don't specify copper weight, you'll almost certainly get 1oz copper. It's the default for good reason—it balances cost, manufacturability, and performance for most applications.

2oz Copper: The Power Handler

When you need to move serious current or dissipate significant heat, 2oz copper becomes essential. It's commonly used in power electronics, automotive applications, and industrial controls.

Complete Side-by-Side Comparison

Here's everything in one table for easy reference:

Resistance and Voltage Drop: The Hidden Cost

Copper weight directly affects resistance, which determines voltage drop along your traces. This matters a lot for power delivery, especially in low-voltage systems.

Notice something interesting? When you size traces properly for the same current and temperature rise, the voltage drop is similar regardless of copper weight. The advantage of heavier copper is that you can achieve this with narrower traces, saving board space.

But what if board space isn't constrained? Then you can use wider traces with lighter copper to achieve lower resistance:

Manufacturing Considerations

Etching Limitations

Thicker copper requires longer etching time, which causes more undercutting. This is why minimum trace and space rules increase with copper weight:

Plating and Hole Quality

Via plating is affected by copper weight too. With heavier copper, more plating is needed to ensure reliable barrel integrity. This can impact via sizing decisions—see our Via Sizing Guide for details.

Cost Impact

The cost increase for heavier copper varies by fab house and quantity:

Impedance and Signal Integrity

Copper weight affects trace impedance because it changes the geometry. Thicker copper means a different height-to-width ratio, which changes characteristic impedance.

For controlled impedance designs, always specify your copper weight when requesting stackup calculations from your fab house. Use our Impedance Calculator to see how copper thickness affects your trace geometry.

Using Mixed Copper Weights

Modern PCB manufacturing allows different copper weights on different layers. This is common in power electronics where you might want:

• 2oz copper on outer layers for power traces and heat dissipation
• 1oz copper on inner signal layers for routing density
• 0.5oz copper on high-speed layers for controlled impedance

Application Selection Guide

Quick Decision Guide

Common Mistakes to Avoid

For more PCB design pitfalls, read our guide on 10 Common PCB Trace Width Mistakes.

Conclusion

Choosing the right copper weight is about matching your design requirements to material capabilities. 1oz copper remains the sweet spot for most applications—it's the default for good reason. Go lighter (0.5oz) when you need fine features or controlled impedance. Go heavier (2oz+) when you need to move serious current or dissipate heat.

The key is to calculate your actual requirements using tools like our Trace Width Calculator and let the numbers guide your decision. Don't over-specify copper weight "just in case"—it adds cost and reduces routing flexibility.