High-Speed PCB Design

PCB Trace Width Calculator

Calculate trace width, voltage drop, and power loss per IPC-2221.

Accurate PCB trace width calculation is critical for thermal management and signal integrity. When current flows through a copper trace, resistance generates heat. This tool uses the IPC-2221 Standard to calculate the minimum width required to keep the temperature rise within safe limits.

It also acts as a Voltage Drop Calculator, ensuring your power delivery network (PDN) maintains sufficient voltage at the load.

Design Parameters

Input
Amps

Thermal Limits

IPC-2221
°C
°C

Required Geometry

Result
Min Trace Width
— mils
(— mm)

Electrical Characteristics

Resistance —
Voltage Drop —
Power Loss —
Max Temp —
FR4 PCB Substrate Width

How to Use

Calculate PCB trace widths in 3 steps.

1

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.

2

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.

3

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.

Common Questions regarding PCB Traces

What is IPC-2221?
IPC-2221 is the generic standard for printed board design. It provides the formula used by most engineers to determine the relationship between current, temperature rise, and trace width.
Internal vs External Layers: What’s the difference?
External layers (Top/Bottom) are exposed to air, allowing better heat dissipation. Internal layers are buried inside the FR4 substrate, which traps heat. Therefore, internal traces must be significantly wider (approx 2x) to carry the same current as external traces.
How does Copper Weight affect width?
“Weight” refers to the thickness of the copper foil. 1 oz/ft² is approx 1.37 mils (0.035 mm) thick. Using heavier copper (e.g., 2 oz) doubles the cross-sectional area, allowing you to use a narrower trace for the same current.