PCB Trace Width Calculator

When high current flows through a PCB trace, it generates heat. To prevent delamination or burning, the trace must be wide enough to dissipate that heat.

This calculator uses the IPC-2221 Standard to determine the minimum required trace width for a given current and allowable temperature rise. It also checks for Voltage Drop and Power Loss.

Design Parameters

Input

Current (I)

Amps

Copper Weight

Layer Type

Thermal Limits

IPC-2221

Temp Rise

°C

Ambient

°C

Trace Length

Required Geometry

Result

Min Trace Width

— mils

(— mm)

Electrical Characteristics

Resistance —

Voltage Drop —

Power Loss —

Max Temp —

IPC-2221 Formulas Explained

Required Area

Area = (I / (k × ΔT^0.44))^(1/0.725)

k = 0.048 (External) or 0.024 (Internal). Result in mils².

Trace Width

Width = Area / (Thickness × 1.378)

Thickness in oz/ft². 1 oz copper ≈ 1.378 mils thick.

Resistance

R = (ρ × L) / (W × T)

ρ (Copper Resistivity) ≈ 1.7e-6 Ω-cm at room temp.

Power Loss

P = I² × R

Energy dissipated as heat along the trace length.

How to Use

Calculate PCB trace widths in 3 steps.

Define Electrical Load

Enter the maximum Current your trace needs to carry. Select the Copper Weight (usually 1 oz) and whether it’s an External or Internal layer.

Set Thermal Constraints

Specify the allowed Temperature Rise (e.g., 10°C means the trace can heat up to 35°C if ambient is 25°C). Higher rise allows thinner traces.

Get Trace Dimensions

The tool calculates the minimum Trace Width in mils and mm. It also provides the DC Resistance and Voltage Drop for the specified length.