PCB Via Current Capacity

Calculate the maximum current a plated through-hole via can carry based on IPC-2221.

PCB Via Cross Section

Via Parameters

Max Safe Current

-- A

Cross-Sectional Area

-- sq mils
Resistance
-- mΩ
Voltage Drop
-- mV

Calculated based on IPC-2221 internal trace formulas.

How PCB Via Current Capacity is Calculated

A PCB via is essentially a tiny cylindrical wire formed by the copper plating inside the drilled hole. Because they are embedded inside the fiberglass FR4 board, they heat up when large currents flow through them.

To calculate the safe current carrying capacity, we use the IPC-2221 standards. First, we find the cross-sectional area of the copper cylinder:
Area = π × (Diameter - PlatingThickness) × PlatingThickness.

Once the area (in square mils) is known, the IPC-2221 formula for internal layers (which are most representative of a via barrel surrounded by FR4) is used to determine the max current for the specified allowable temperature rise (ΔT):
I = 0.024 × ΔT0.44 × Area0.725

It's generally recommended practice to use multiple vias (stitching) for high current paths rather than relying on a single large via, to reduce both resistance and parasitic inductance.