Engineering & Hardware Utilities
Precision calculators for PCB trace geometry, passive networks, RF microstrip impedance, and MCU peripherals based on IPC standards.
IPC-2221 PCB Trace Width Calculator
Conductor width, cross-section area, resistance, and temperature rise
Trace Parameters
IPC-2221Computed Width & Characteristics
Live Trace Cross-Section
Mathematical Formula & Engineering Rules
The IPC-2221 trace width calculation is based on the empirical formula relating current, temperature rise, and cross-sectional area:
- I: Current in Amperes (A)
- ΔT: Allowable temperature rise above ambient in °C
- A: Cross-sectional area in mils2
- k: Constant (0.048 for external layers, 0.024 for internal layers)
- Width (W): W = Area / (Thickness × 1.378 mils/oz)
Worked Engineering Example
Target: Carry 2.5A on an external layer with 1.0 oz copper and a 10°C allowable temperature rise over a 50mm length.
- Calculate cross-sectional area: A = (2.5 / (0.048 × 100.44))(1/0.725) = 34.6 mils2.
- Convert 1.0 oz copper to thickness: 1.0 oz = 1.378 mils (35 μm).
- Calculate required width: W = 34.6 mils2 / 1.378 mils = 25.1 mils (0.638 mm).
- Resulting trace resistance over 50mm: R ≈ 0.038 Ω with 0.095V voltage drop.
Frequently Asked Questions
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