PCB Power Design

Current Capacity Calculator

IPC-2221 Compliant • Max Current Analysis

Determine the maximum safe current for your PCB traces. Input your trace width and copper weight to calculate the current capacity with specified temperature rise.

Trace Parameters

Trace Width (mm)

Copper Weight (oz/ft²)

Layer Type

Temperature Rise (°C)

Trace Length (mm) - for resistance calc

Current Capacity Results

Quick Reference: Current Capacity (10°C Rise)

Trace Width	1oz Ext	1oz Int	2oz Ext	2oz Int
10 mil	0.5A	0.3A	1.0A	0.6A
20 mil	1.0A	0.6A	2.0A	1.2A
50 mil	2.5A	1.5A	4.5A	2.8A
100 mil	4.5A	2.8A	8.0A	5.0A
200 mil	8.0A	5.0A	14A	9.0A

*Values are approximate. Use calculator for precise results.

IPC-2221 Current Capacity Formula

I = k × ΔT^0.44 × A^0.725

I = Current (Amps)

k = 0.048 (ext) / 0.024 (int)

ΔT = Temperature Rise (°C)

A = Cross-section Area (mil²)

Current Capacity Design Tips

🌡️

Temperature Rise

Lower temperature rise = more conservative design. Use 10°C for general applications, 20°C for space-constrained designs, 5°C for high-reliability applications.

📐

Safety Margin

Always apply a 20-50% safety margin to calculated values. Account for manufacturing variations, ambient temperature, and airflow conditions.

⚡

High Current

For currents above 10A, consider using multiple traces in parallel, adding copper planes, or using thicker copper weights (2oz or higher).

Need to Calculate Trace Width?

If you know your required current and want to find the minimum trace width, use our trace width calculator instead.

Trace Width Calculator Via Current Calculator

Current Capacity FAQ

What determines PCB trace current capacity?

Current capacity depends on trace width, copper thickness, layer position (internal vs external), acceptable temperature rise, and ambient conditions. Wider, thicker traces on external layers carry more current.

Why can external layers carry more current?

External layers dissipate heat through convection to air, while internal layers are surrounded by insulating FR4. This gives external traces approximately 2× the current capacity.

What temperature rise should I use?

Common choices are 10°C (conservative), 20°C (moderate), or 30°C (aggressive). Consider your ambient temperature and reliability requirements when choosing.

How do I handle high current (>10A)?

Options include: wider traces, thicker copper (2oz+), parallel traces, copper planes, thermal vias for heat dissipation, and active cooling in extreme cases.