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PCB Trace Width & Current Calculator

IPC-2152 based PCB trace width calculator. Enter current, temperature rise, copper weight and layer — get minimum trace width, resistance, voltage drop and power dissipation. Includes quick-reference table and width-vs-current plot.

// Electrical Requirements
A
°C
°C
mm
V
// PCB Stack-up Parameters
// IPC-2152 Method
IPC-2152 trace width equation:
W = I / (k × ΔTb × (ACu)c)
where ACu = W × t (copper cross-section area, mil²)
k=0.048 (ext), 0.024 (int)  ·  b=0.44  ·  c=0.725

Solved iteratively for W:
ACu = (I / (k × ΔTb))1/c mil²
W = ACu / tCu (in mils)

Trace resistance:
R = ρCu × L / (W × t)    [ρ = 1.724×10−8 Ω·m]
Corrected for temperature: R(T) = R20(1 + 0.00393(T−20))
// Results
Trace Sizing (IPC-2152)
Minimum trace width—
Recommended width (1.5× safety)—
Copper cross-section—
Copper thickness tCu—
Max current at recommended W—
Electrical Performance
Trace resistance R—
R at operating temperature—
Voltage drop ΔV—
% voltage drop—
Power dissipated in trace—
Actual temperature rise—
// Trace Width vs Current (at selected ΔT & Cu weight)
External layer Internal layer
// Quick Reference — 1 oz External, ΔT=10°C
CurrentMin WidthRec. WidthResistance/cmUse case
RF design rules: For RF signal traces, use 50Ω microstrip width — not this IPC-2152 width (which is for DC current). Only use this calculator for power supply traces, bias feeds, and DC routing. For RF signal paths, use the Microstrip Calculator.

PCB Trace Width and Current Capacity — IPC-2152 Guide

PCB trace width for current carrying is governed by IPC-2152, the standard for determining the current-carrying capacity of printed board conductors. The key variables are: current (A), allowable temperature rise (ΔT), copper weight (oz/ft²), and whether the trace is on an external or internal layer. External traces dissipate heat more effectively than internal traces, so they can carry more current at the same width.

External vs Internal Layers

External traces have direct convective and radiative cooling, making them roughly twice as current-capable as internal traces at the same width and ΔT. The IPC-2152 k-factor is 0.048 for external and 0.024 for internal. For high-current traces, always route on external layers where possible, and consider using copper pours and thermal vias to help dissipate heat from internal layers.

Temperature Rise Budget

IPC-2152 allows you to specify ΔT — the permitted temperature rise above ambient. A ΔT of 10°C is conservative and widely used for signal traces. For power traces, ΔT of 20–30°C is often acceptable, giving a narrower (cheaper) trace. However, always verify that T_amb + ΔT remains well below the PCB's glass transition temperature (T_g ≈ 135°C for standard FR4) and below the component derating temperatures.

RF vs Power Trace Width

This calculator is for DC/power traces only. RF signal traces must be sized for characteristic impedance (typically 50Ω), not current capacity. A 50Ω microstrip on FR4 at 1 oz is typically 2.8–3.0 mm wide on a 1.6 mm substrate — much wider than the IPC-2152 minimum for a typical RF signal level of −10 dBm (0.7 mA). Never size RF signal traces for current; always use the Microstrip Calculator for RF routing.