What is plating thickness and how does it affect via current capacity?

Plating thickness is the amount of copper electroplated onto the via wall after drilling. Standard plating is 25 micrometers (1 mil). Heavier plating (35 um or more) creates a thicker copper wall, which increases the cross-sectional area of the via and allows it to carry more current before heating up. Thicker plating also reduces via resistance and voltage drop.

How much does via resistance contribute to overall power loss in a circuit?

For a single via carrying 1 amp with standard plating, resistance is typically 1-3 milliohms, which at 1A creates only 1-3 millivolts of drop - usually negligible. However, for high-current power delivery (10+ amps), multiple thin vias, or long PCB thickness, via resistance can become significant. Use multiple vias in parallel for high-current connections and check the calculated voltage drop against your circuit's tolerance budget.

Should I use multiple vias in parallel, and how does it affect current capacity?

Multiple vias in parallel simply add their individual current capacities together. For example, two 2-amp vias in parallel can safely carry 4 amps (assuming equal thermal distribution and proper board layout). Use multiple vias to distribute heat, reduce resistance, and achieve higher current capacity than a single large via. It also improves PCB reliability by avoiding current crowding.

PCB Via Current Calculator

Enter your via drill size, copper plating thickness, and how much the board is allowed to heat up. Get the maximum safe current, via resistance, voltage drop, and how many vias to use in parallel. Runs entirely in your browser - nothing uploaded.

IPC-2221 ? Max current (A) Via resistance (mΩ) ? Voltage drop (mV) Power dissipation (mW) Parallel vias mm / mil toggle

Units

Via Geometry

Drill diameter common presets

Drill diameter mm ?

Copper plating thickness (µm) ?

µm

Via length / PCB thickness mm ?

Allowable Temperature Rise ?

Custom temperature rise (C)

Parallel Vias ?

Number of vias in parallel

Standard

IPC standard reference

IPC-2221 (1998) is the widely used conservative baseline. It was derived from single-layer board data. Results are on the safe side for most designs.

Max current - single via (IPC-2221)

1 via = - A

Via resistance ?

milliohms

Voltage drop ?

millivolts at max current

Power dissipated ?

milliwatts at max current

Copper cross-section ?

mil² and mm²

Via current capacity and thermal management

How via current rating is calculated using IPC-2221

PCB vias are small copper tubes that connect traces across layers. The IPC-2221 standard defines via current capacity using the same empirical formulas as traces, based on the copper cross-sectional area (determined by drill diameter and plating thickness) and the allowable temperature rise. The calculator computes this area as a hollow cylinder - the outer diameter includes plating thickness, and the inner diameter is the drilled hole. Larger vias or thicker plating increase capacity proportionally. For example, increasing plating from 25 µm to 50 µm can boost current capacity by 20-30% because the copper wall becomes thicker.

Via resistance, voltage drop, and power dissipation

Real vias have DC resistance, which causes voltage drop and dissipates power as heat. This calculator reports via resistance in milliohms. For low currents (under 2 amps) with standard plating, via resistance is typically 1-3 mΩ and contributes only millivolts of drop - usually not a concern. However, for high-current power delivery circuits (10+ amps), multiple thin vias, or long PCB thickness (thick boards), via resistance becomes significant and must be accounted for in your power budget. Use multiple vias in parallel to reduce resistance and distribute current evenly across the PCB.

FAQ

What is the difference between finished via diameter and drill diameter?

Drill diameter is the size of the hole before plating. Finished via diameter includes the copper plating on both the inside and outside of the via wall. The calculator uses drill diameter and plating thickness to compute the cross-sectional area of copper. A typical 10 mil drill hole with 1 mil plating on each side results in about 10.5-11 mil effective wall thickness for current-carrying purposes.

Do I need to account for via temperature rise separately from trace temperature?

Vias are much smaller than traces (on a per-unit-area basis) and can run hotter per unit current. However, vias are usually short (PCB thickness only) so voltage drop and power dissipation are modest. The bigger concern is avoiding via thermal hotspots near sensitive components. Distributing high current across multiple vias spreads the heat and is a best practice for reliability.

Can I exceed the calculated current if the board is cooled actively?

Active cooling (fans, liquid cooling) can extend via capacity somewhat by lowering ambient temperature, but it does not change the fundamental limit set by copper cross-section and resistivity. A better approach is to use thicker copper, larger diameter vias, or more vias in parallel. Relying on exotic cooling for basic current distribution is unreliable and poor design practice.

Last reviewed: June 19, 2026