PCB Trace Current Calculator
Calculate maximum current carrying capacity and electrical properties of PCB traces
Calculate PCB Trace Current Capacity
Width of the copper trace
Copper thickness (1 oz ≈ 35 μm, 2 oz ≈ 70 μm)
Total length of the trace (for resistance calculation)
Acceptable temperature rise above ambient (typically 10-20°C)
Additional Parameters
Operating environment temperature
Current Capacity Results
Configuration: External trace -0.00 × 0.000 mm, 0.0 mm length
Standard: IPC-2221 calculations - Temperature: 10.0°C rise, 35.0°C operating
Current Capacity Analysis
Example Calculation
Power Supply Trace Design
Application: 12V, 2A power distribution
Trace: External, 2mm wide, 35μm thick (1 oz copper)
Temperature Rise: 10°C maximum
Result: ~2.5A capacity (safe for 2A load)
Signal Trace Design
Application: Digital I/O, low current
Trace: Internal, 0.2mm wide, 35μm thick
Temperature Rise: 10°C maximum
Result: ~0.15A capacity (adequate for logic signals)
Copper Thickness Reference
Temperature Rise Guidelines
10°C
Conservative design, high reliability
20°C
Standard design practice
40°C
Maximum for most applications
Design Tips
External traces handle 2× more current than internal
Doubling width roughly doubles current capacity
Thicker copper increases current handling
Use thermal vias for high-current internal traces
Consider voltage drop for long traces
Add safety margin (typically 50%)
Understanding PCB Trace Current Capacity
Why Current Limits Matter
PCB traces have current limitations due to resistive heating. When current flows through a trace, it generates heat due to the trace's resistance. Excessive current can cause trace failure, PCB damage, or circuit malfunction.
Key Factors
- •Cross-sectional area: Width × thickness determines current capacity
- •Location: External traces dissipate heat better than internal
- •Temperature rise: Acceptable heating above ambient
- •Copper thickness: Thicker copper handles more current
IPC-2221 Standard
I = k × (ΔT)^b × A^c
- I: Maximum current (Amperes)
- k: Constant (0.048 external, 0.024 internal)
- ΔT: Temperature rise (°C)
- A: Cross-sectional area (mil²)
- b, c: Constants (0.44, 0.725)
Safety Note: Always add a safety margin to calculations. Consider derating factors for high-temperature environments and long-term reliability.