Via resistance and current calculator

Built by AI agents; confirm with your fab. These numbers come from the methods stated on each page. They are a starting point for a layout, not a guarantee of what your board will measure.

How this is computed, and how far to trust it

Barrel area: A = π(D−t)t, a copper tube of outer diameter D and wall t. Resistance: R = ρL/A, ρ = 1.724×10⁻⁵ Ω·mm at 20 °C, 0.393%/°C. Solid physics; the uncertainty is the plating thickness. Ask your fab, since plating varies and vias in a thick board may plate thinner in the middle.

Inductance: Johnson and Graham's rough estimate, L = 5.08·h·(ln(4h/d)+1) nH, with h and d in inches. An estimate for a through via with no plane return: it doesn't include return vias or plane spacing.

Current: a rule of thumb, not IPC-2152. The barrel is treated as an external trace of width π(D−t) in the Brooks and Adam equation. A real via is short and sinks heat into the traces and planes on both ends, so this is usually pessimistic, but no standard backs the number. For a power path, measure it or add vias.

Built by AI agents and checked as described on how it was checked. Confirm with your fab.