PCB Via Current Calculator
Estimate the electrical loading of plated-through PCB vias from finished hole diameter, barrel plating, board thickness, parallel via count, and total net current.
The calculator reports barrel area, resistance, voltage drop, power loss, current density, and a conservative loading status for PCB power-routing review.
Engineering tool
PCB Via Current Calculator
Estimate via barrel area, resistance, current sharing, voltage drop, power loss, and loading risk.
Finished drilled diameter after copper plating.
Nominal copper thickness on the via barrel wall.
Approximate current path through the board thickness.
Current shared by all parallel vias.
Used for conservative current-density screening.
Whole number of similar vias sharing the net current.
Result console
- Copper barrel area
- 0.023562mm²
- Current per via
- 500mA
- Resistance per via
- 1.170701mΩ
- Voltage drop
- 0.585351mV
- Power loss per via
- 0.292675mW
- Total power loss
- 1.170701mW
- Current density
- 21.220659A/mm²
- Equivalent resistance
- 0.292675mΩ
Via loading status
Safe
The electrical loading is within the calculator's conservative screening range. Verify finished plating, pad connection, plane spreading, and thermal performance with fabrication data and testing.
Formula reference
PCB Via Barrel Formulas
The barrel is approximated as a thin copper cylinder. All electrical calculations use SI units and copper resistivity at nominal room temperature.
Via barrel area: A ≈ π × D × tVia resistance: R = ρ × L / ACurrent per via: Ivia = Itotal / NVoltage drop: Vdrop = Ivia × RPower per via: Pvia = Ivia² × RTotal power: Ptotal = N × PviaVariable definitions
- D
- finished hole diameter
- t
- copper barrel plating thickness
- L
- via barrel length or PCB thickness
- N
- number of parallel vias
- ρ
- copper resistivity, 1.724 × 10⁻⁸ Ω·m
Worked Example
For four 0.3 mm finished vias with 25 µm plating through a 1.6 mm board carrying 2 A total, each via carries 0.5 A.
The approximate barrel area is 0.02356 mm², resistance is 1.17 mΩ per via, voltage drop is 0.59 mV, and power loss is about 0.29 mW per via.
Engineering Notes
- Via current depends on barrel plating thickness and finished hole diameter.
- Multiple parallel vias reduce current per via, equivalent resistance, and localized heating.
- Via thermal performance depends on connected copper planes, pads, stackup, and airflow.
- PCB manufacturer finished-hole and plating tolerances should be included in worst-case analysis.
- High-current vias should be verified against fabrication rules and thermal measurements.
Support reference
FAQ
How much current can a PCB via carry?
Via current capability depends on finished hole diameter, barrel plating, board thickness, copper-plane connections, allowed temperature rise, and fabrication tolerance. Use the result as a screening estimate and validate high-current designs.
How do you calculate via resistance?
Approximate barrel area as π × finished hole diameter × plating thickness, then calculate R = ρL/A using copper resistivity and the via barrel length.
Why use multiple vias in parallel?
Parallel vias divide current, reduce equivalent resistance and voltage drop, spread heat, and improve redundancy. Layout symmetry helps the vias share current more evenly.
Does via plating thickness matter?
Yes. Thicker barrel plating increases copper area and lowers resistance, current density, and I²R heating. Use the fabricator's minimum finished plating for worst-case design.
How does PCB thickness affect via resistance?
A thicker PCB creates a longer copper barrel. Resistance and power loss increase approximately in proportion to barrel length when diameter and plating remain unchanged.
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