KiCad "Via diameter" DRC error: via pad too small
KiCad design rule check (PCB) message: Via diameter (via_diameter in kicad-cli reports).
What it means
A via's copper pad is smaller than the minimum via diameter in your rules. Increase the via size, or lower the rule if your fab supports smaller vias.
Common causes
- Vias placed with a custom size smaller than the board minimum.
- A net class whose via size is below the board minimum.
How to fix it
- Set the via size in Board Setup → Net Classes or Pre-defined Sizes.
- Select the vias and use Edit → Edit Track & Via Properties to apply the new size.
Where the setting lives
Board Setup → Design Rules → Constraints → Minimum via diameter.
What fabs need
JLCPCB lists 0.25 mm as the minimum via pad diameter.
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Checked against KiCad 10's source and documentation. Last reviewed 2026-11-07.
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