route PCB Design Calculator
PCB Trace Width Calculator
IPC-2221 compliant trace width and current capacity calculation. Supports external and internal copper layers with selectable temperature rise and copper weight.
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Trace Parameters
Current (I) Amps
Temperature Rise (ΔT) °C
Typical: 10°C (safe), 20–30°C (acceptable), >40°C (check reliability)
Copper Weight
Layer
Internal layers use k=0.024 (IPC-2221) — approximately half the current capacity of external layers (k=0.048).
Check Width mil (optional)
Enter a specific trace width to calculate its maximum current capacity.
Min Trace Width
—mil
Cross-Section Area
—mil²
Resistance / inch
—mΩ/in
IPC-2221 Table 6-1 Formula:
Area (mil²) = (I / (k × ΔT0.44))1/0.725
Where k = 0.048 for external layers, k = 0.024 for internal layers. Copper thickness: 1 oz/ft² = 1.378 mil (35 µm).
Area (mil²) = (I / (k × ΔT0.44))1/0.725
Where k = 0.048 for external layers, k = 0.024 for internal layers. Copper thickness: 1 oz/ft² = 1.378 mil (35 µm).
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Trace Width vs. Current Capacity
Current-carrying capacity at your selected ΔT. ● marks the minimum width for your input current.
functions IPC-2221 Equations
Area (mil²)= (I / (k × ΔT^0.44))^(1/0.725)
Width (mil)= Area / Thickness_mil
k_ext= 0.048 (external layer)
k_int= 0.024 (internal layer, ×0.5 derating)
I_max= k × ΔT^0.44 × Area^0.725 (inverse)
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Note: These tools and articles provide theoretical estimates for educational purposes. Actual results may vary depending on real-world component tolerances, parasitics, and thermal conditions.