PCB Trace Width Calculator
Calculate minimum trace width for current capacity (IPC-2221)
📐 Input Parameters
°C
°C
Common Current Presets
📊 Results
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IPC-2221 Note: These calculations use the IPC-2221 standard formulas.
For safety-critical designs, add 10-20% margin and verify with your PCB manufacturer.
Internal layers dissipate heat less efficiently than external layers.
Quick Reference: Trace Width vs Current (1oz copper, 10°C rise, external)
| Current | Min Width (mil) | Min Width (mm) | Notes |
|---|
Understanding the Formula
The IPC-2221 standard provides the following formula for trace current capacity:
I = k × ΔT0.44 × A0.725
Where:
- I = Current (Amps)
- k = 0.048 for external layers, 0.024 for internal layers
- ΔT = Temperature rise above ambient (°C)
- A = Cross-sectional area (mil²)
Solving for area: A = (I / (k × ΔT0.44))1/0.725
Then width = Area / Thickness
Copper Weight to Thickness
| Copper Weight | Thickness (µm) | Thickness (mil) | Common Use |
|---|---|---|---|
| 0.5 oz | 17.5 | 0.7 | Flexible PCBs, fine pitch |
| 1 oz | 35 | 1.4 | Standard (most common) |
| 2 oz | 70 | 2.8 | Power circuits |
| 3 oz | 105 | 4.2 | High current |
| 4 oz | 140 | 5.6 | Very high current |