Wall Gap Calculator — Minimum Resolvable Gap

When a gap is narrower than one extrusion width, the slicer has two choices: skip it (leaving a gap) or fill it with a thin extrusion. Many slicers fill thin gaps to avoid weak spots, which eliminates the intended gap.

The practical minimum is 0.4mm (one nozzle width). Gaps of 0.5-0.6mm print more reliably. Anything under 0.4mm will likely be filled by the slicer or leave an inconsistent channel.

Enable "Detect thin walls" and adjust "Thin wall minimum width" in your slicer. Some slicers have "Gap fill" settings that control whether narrow spaces are filled. Reducing line width can help print slightly narrower gaps.

Narrow gaps between walls create weak points because there is less material connecting the two sides. If structural integrity matters, ensure gaps are clearly wider than the nozzle so the slicer creates clean separate walls.