Published 2026-09-03 · 2 min read
How thick should walls be for 3D printing
Wall thickness is the single number that decides whether your part survives being held. Not infill, which is what most people reach for first. Here are the real figures for a standard 0.4 mm nozzle.
The absolute minimum: two extrusion widths
A wall should be a multiple of the extrusion width. With a 0.4 mm nozzle the usual extrusion is also 0.4 mm, so good walls are 0.8, 1.2, 1.6 mm and so on.
A 1 mm wall is not better than 0.8: the slicer lays two 0.4 passes and is left with a 0.2 mm gap it fills badly. Always round to a multiple.
- Decorative parts, no mechanical load: 0.8 mm.
- Parts held in the hand or screwed together: 1.6 mm.
- Load-bearing parts: 2.4 mm and up.
- Threads and snap fits: at least 2 mm of material around them.
Perimeters matter more than infill
Under bending, the material at the surface carries almost all the load; the core barely works. That is why a part with 4 perimeters and 15% infill is stronger than one with 2 perimeters and 50% infill — while using less plastic and less time.
If you want strength, raise the perimeter count before you raise infill. The difference shows up immediately in a break-it-by-hand test.
Where prints actually break
A print almost always fails between layers, not within them: layer adhesion is the weakest link. A hook printed lying down holds several times more than the same hook printed standing up.
So orientation on the bed matters as much as thickness. Think about where the force comes from, and place the part so the force does not pull the layer lines apart.
Check thickness in the model, not in the slicer
The slicer shows the problem only after everything is drawn. A parametric editor shows it from the start: wall thickness is a number you can change at any time, and the part rebuilds.
In GrafitGo you can cut the part with the section plane to see the real internal thickness, and the reported volume tells you instantly how many grams of PLA a change costs.
How many perimeters should I use?
Three for ordinary parts, four or five for parts under load. Above six the gain gets small compared with the added print time.
How much infill is enough?
15–20% for most parts. Above 40% you rarely gain enough to justify the material if your walls are already thick.
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