Engineering Tools

PCB Via Current Calculator

Estimate the maximum safe current capacity of a plated-through via hole using the IPC-2221 standards.

Max Estimated Current

0.00 A

Cross-Sectional Area

0.00 sq mils

How is Via Current Calculated?

The calculation is based on the IPC-2221 standards for internal trace heating. A via is treated thermally similar to an internal trace since it is surrounded by FR4 material, which restricts heat dissipation compared to outer traces.

1. Calculate Plating Cross-Sectional Area

A via is essentially a copper tube. To find its cross-sectional area, we subtract the area of the inner empty cylinder from the outer plated cylinder.

Area = π × (D² - (D - 2t)²) / 4
Where D is the finished hole diameter, and t is the plating thickness.

2. Apply IPC-2221 Internal Formula

Once the area is found in square mils (mils²), the IPC-2221 formula for internal traces is applied:

I = k × ΔT^0.44 × Area^0.725

I: Current in Amperes.
k: Derating constant (k = 0.024 for internal layers/vias).
ΔT: Allowed temperature rise above ambient (typically 10°C or 20°C).

Best Practices for Power Vias

When routing heavy currents (like motor drivers or power supplies), a single via is rarely enough, and using one massive via creates manufacturing issues (solder wicking, thermal relief problems).

The Golden Rule: It is always better to use an array of multiple small vias (e.g., three 0.3mm vias) rather than one giant via. Multiple small vias provide a significantly larger surface area for current flow and better thermal dissipation into the surrounding copper pours.