Wall Thickness Calculator
Design walls in whole multiples of your line width and they come out solid, every time — here's how many perimeters that takes.
Usually 100–120% of nozzle diameter.
Why "2mm walls" isn't always 2mm walls
A slicer builds walls from whole perimeter lines, so a modeled wall thickness that isn't an exact multiple of the line width gets rounded to the nearest whole number of perimeters — a 2mm wall at a 0.42mm line width doesn't divide evenly (4.76 perimeters), so the slicer either prints 4 perimeters (1.68mm, thinner than intended) or 5 (2.1mm, thicker), depending on its rounding behavior. Modeling wall thickness as an exact multiple of line width from the start avoids this entirely.
Minimum wall thickness for actual strength
A single 0.4mm-nozzle perimeter is rarely enough for anything handled or load-bearing — 2–3 perimeters (roughly 0.8–1.3mm at a 0.42mm line width) is a common practical minimum for small functional parts, and thin-walled parts under any bending stress benefit from more perimeters over more infill, since walls do most of the structural work in bending.