This PCB Trace Width Calculator is based on the legacy IPC-2221 standard, a widely recognized guideline for estimating trace widths based on current, copper weight, and temperature rise. Although IPC-2221 has been succeeded by the more modern and detailed IPC-2152, which incorporates empirical data and thermal modeling, IPC-2221 remains popular for its simplicity and conservative approach. Its results, particularly for external traces, tend to be conservative, often recommending wider traces than strictly necessary. While modern PCB design software may use IPC-2152 for improved accuracy, this calculator is ideal for quick, first-approximation results, making it a valuable tool for early-stage design and educational purposes.
Input for Trace Width Calculation:
Input for Resistance, Voltage Drop and Power Loss Calculation:
Ω·m (Copper at 20°C typ. 1.68e-8Ω·m)
/°C (Copper typ. 0.00393/°C)
Calculated Output:
Internal Trace
Ω
V
W
External Trace
mil
Ω
V
W
X Min: X Max:
IPC-2221 PCB Trace Width Formula
\[ w = \frac{1}{t}\cdot\left(\frac{I}{k \cdot T_{Rise}^b}\right)^{\frac{1}{c}} \]
Where:- \( I \) = Current (A)
- \( T_{Rise} \) = Temp. rise (°C)
- \( t \) = Copper weight (mil), where 1 oz/ft² ≈ 1.378 mil
- \( k \) = 0.024 for internal layers, \( k \) = 0.048 for external layers
- \( b \) = 0.44
- \( c \) = 0.725
Assumptions used in IPC-2221 Trace Width Formula:
- Assumes steady-state (not pulsed) current conditions.
- Trace is isolated in air, with no significant nearby heat sources or planes.
- Uniform copper thickness across the entire trace length.
- No forced convection or external cooling is accounted for.
- Uses different constants for internal (k = 0.024) and external (k = 0.048) layers.
- Formula is empirical and derived from legacy test data.
- Assumes constant cross-sectional area (no tapering or widening).
- Does not include resistance from vias, pads, or connectors.
Trace Resistance Formula
\[ R = \rho \cdot \frac{L}{w \cdot t} \cdot \left(1 + \alpha \cdot (T_{Ambient} + T_{Rise} - 20)\right) \]
Where:- \( \rho \) = Resistivity of copper (Ω·m)
- \( L \) = Trace length (m)
- \( w \) = Trace width (m)
- \( t \) = Copper thickness (m)
- \( \alpha \) = Temperature coefficient of copper (/°C)
- \( T_{Ambient} \), \( T_{Rise} \) in °C
Voltage Drop Formula (Ohm's Law)
\[
V = I \cdot R
\]
Where:- \( V \) = Voltage drop (V)
- \( I \) = Current through the trace (A)
- \( R \) = Trace resistance (Ω)
Power Loss Formula
\[
P = I^2 \cdot R
\]
Where:- \( P \) = Power dissipated in the trace (W)
- \( I \) = Current through the trace (A)
- \( R \) = Trace resistance (Ω)
Disclaimer: This calculator is provided for educational and informational purposes only. While efforts have been made to ensure the correctness of the formulas, unit conversions, and default parameters, Pylon Technology Solutions Ltd. (PTSolns) does not guarantee the accuracy, completeness, or suitability of the results for any specific application. Calculated values such as trace width, resistance, voltage drop, and power loss are estimates based on standard industry formulas (e.g., IPC-2221) and may not reflect real-world performance. It is the user's responsibility to verify results and ensure compliance with relevant design standards and safety requirements. PTSolns assumes no liability for any loss, damage, or consequences resulting from the use of this tool. This calculator is subject to modifications or updates at any time without prior notice.