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Via Current Capacity Calculator

Work out via current capacity instantly with clear inputs, formula shown and shareable results.

About Via Current Capacity Calculator

A via's conductor is the plated barrel, an annulus of copper whose area is pi times diameter times plating thickness. Applying the same IPC-2221 relation used for traces gives the current capacity, which is why power connections between layers use several vias in parallel rather than one.

Formula

Via capacity

barrel area = pi x d x plating thickness; current from the IPC-2221 area relation

Worked example

With the default values below, Via Current Capacity Calculator returns Current per via of 2.29. Change any input above and every figure here is recalculated in your browser.

Inputs used

Finished via diameter
0.3 mm
Plating thickness
25 µm
Board thickness
1.6 mm
Permitted temperature rise
20 °C

Results

Current per via
2.29 A
Barrel cross-sectional area
0.02160 mm²
Via resistance
1,274.17 mΩ
Vias needed for 5 A
3 vias

Step by step

  1. 1Values used
  2. 2Via capacity
  3. 3Current per via= 2.29 A
  4. 4Barrel cross-sectional area= 0.02160 mm²
  5. 5Via resistance= 1,274.17 mΩ
  6. 6Vias needed for 5 A= 3 vias

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 5 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

Frequently Asked Questions

Why is a single via not enough for power?

A 0.3 mm via with 25 micron plating carries only about 1-2 A for a 20 degree rise. Power nets therefore stitch multiple vias in parallel.

Does via length affect current capacity?

Barely — capacity is set by cross-section and cooling. Length affects resistance and therefore voltage drop and local heating.

Related Calculators

Via Current Capacity Calculator – Calculate Current per via