🔌 PCB Trace Width & Power Calculator

🎯 Getting Started

This tool calculates the minimum PCB trace width required to safely carry a given current without overheating. Calculations are based on IPC-2221 and IPC-2152 industry standards.

• Current: The maximum current the trace will carry (Amperes)
• Temperature Rise: How much the trace temperature can increase above ambient (typically 10-30°C)
• Copper Thickness: The copper weight of your PCB (typically 1 oz/ft²)
• Layer Type: External layers dissipate heat better than internal layers

📐 IPC-2221 Formula

The industry-standard formula for trace width calculation:

A = (I / (k × ΔT^0.44))^1.378

• A = Cross-sectional area (square mils)
• I = Current (Amperes)
• k = Constant (0.048 for external, 0.024 for internal layers)
• ΔT = Temperature rise above ambient (°C)

Width is then calculated from area: W = A / (Thickness × 1.378)

🔥 Temperature Rise Guidelines

• 10°C: Conservative design, high reliability (recommended for critical applications)
• 20°C: Standard design, good balance of size and safety
• 30°C: Compact design, acceptable for most consumer electronics
• 40°C+: Aggressive design, requires thermal analysis

⚠️ Lower temperature rise = wider traces but better thermal performance and reliability.

⚡ Copper Thickness (Weight)

PCB copper is specified in ounces per square foot:

• 0.5 oz/ft²: 17.5 µm thick, low-cost boards
• 1 oz/ft²: 35 µm thick, standard PCB manufacturing (most common)
• 2 oz/ft²: 70 µm thick, high-current applications
• 3 oz/ft²: 105 µm thick, power electronics

Thicker copper allows narrower traces for the same current rating.

🌡️ Internal vs External Layers

External Layers (Top/Bottom): Better heat dissipation through air convection and radiation. Can handle more current for the same trace width.

Internal Layers (2+ layer boards): Heat trapped between layers, poorer thermal performance. Require wider traces or thicker copper for the same current.

💡 External layer traces can carry ~2x the current of internal traces at the same width and temperature rise.

💡 Design Tips

• Always add 20-30% safety margin to calculated trace widths
• Use multiple parallel traces or copper pours for high-current paths (>3A)
• Keep high-current traces short to minimize voltage drop and heat generation
• Consider using thicker copper (2 oz) for power supplies and motor drivers
• Place power traces on external layers when possible for better cooling
• Use thermal relief patterns for connections to large copper pours

📏 Common Applications

• Signal traces: <100mA → 0.2-0.4mm (8-15 mils) typical
• Logic power (3.3V/5V): 0.5-2A → 0.5-2mm (20-80 mils)
• Motor drivers: 2-5A → 2-5mm (80-200 mils) or copper pour
• Power supplies: 5A+ → Use copper pours, not traces