Via Current & Properties Calculator
Estimate plated via current capacity, resistance, voltage drop, inductance, capacitance, and aspect ratio.
About via current estimates
A_barrel ≈ π × finished diameter × plating thickness
The plated barrel is treated as a conductor and rated with the same IPC-2221 estimate used for traces. Switch the mode to find the current a via can carry, or the diameter needed for a target load current. Resistance, drop, parasitic inductance/capacitance, and aspect ratio follow from the geometry.
How it works
A plated through-hole via carries current in the thin copper barrel on its wall, not through a solid post — so the conducting cross-section is roughly the circumference times the plating thickness. A typical 25 µm plated barrel in a 0.3 mm via has only about 0.024 mm² of copper, comparable to a narrow trace, which is why one via often isn't enough for a high-current net. Because the barrel is short, its resistance is small, but its current capacity is set by how much the copper can heat before it's damaged — the same IPC-2221 temperature-rise limit used for traces.
Worked example and the fix for high current
If a single via only carries a couple of amps at your allowed temperature rise, the standard answer is to use several in parallel: current splits between them and the effective copper area adds up, so four vias share the load roughly four ways. Designers routinely stitch a field of vias under a power pad or thermal pad for exactly this reason.
Limits
These are first-order estimates. Real via ratings depend strongly on plating quality, nearby copper planes that spread heat, and whether the via is filled — so confirm against your fabricator's capabilities before committing a high-current design. For the trace side of the same net, use thePCB trace current calculator.
Plating thickness varies more than you would like
A via's current capacity depends on the thickness of the plated barrel, and that is a process parameter rather than something you specify precisely. Typical plating is around 20-25 µm but it varies between fabricators and across a panel, and it thins in high-aspect-ratio holes. Because a single via's cross-section is far smaller than the trace feeding it, the practical answer for a high-current net is several vias in parallel rather than one sized exactly — the margin is cheap and the plating is not under your control.