How many perimeters and how much infill should I use?
The strength of an FDM part comes mainly from its walls, not its infill. Increasing from 2 to 4 perimeters provides more strength than doubling the infill, and takes much less time.
What the failure looks like
This isn't a failure: it's the setting where most people waste time and material. Neither 100% infill is the answer, nor does 10% work for everything.
Causes, most likely first
- 01
Default profiles
Almost all default profiles come with 2 perimeters and 15-20% infill: a generic compromise.
- 02
Confusing infill with strength
Infill distributes the load, but the outer skin does the heavy lifting.
Step-by-step fix
Decorative
2 perimeters, 10% infill, gyroid pattern, 3 top layers.
Standard functional
3-4 perimeters, 20-25% infill, gyroid or cubic, 4-5 top layers.
Load-bearing technical
4-6 perimeters, 30-40% infill, cubic or rectilinear aligned with the load, 5-6 layers.
Display models and pure volume
2 perimeters, 5-8% lightning infill if it bears no load.
Parts clamped with screws
Max out perimeters around the hole; infill matters little.
| Use | Perimeters | Infill | Pattern |
|---|---|---|---|
| Decorative / figure | 2 | 10% | Gyroid |
| Domestic functional | 3 | 20% | Gyroid |
| Load-bearing technical | 4-6 | 30-40% | Cubic |
| Display model / volume | 2 | 5-8% | Lightning |
| Flexible part (TPU) | 2-3 | 5-15% | Gyroid |
So it doesn't happen again
- Create three saved profiles in your slicer and stop improvising for every part.
- If you need more strength, increase perimeters before infill.
Related questions
Is gyroid always the best pattern?
It is the best all-rounder: isotropic and fast. For load in a specific direction, aligned rectilinear performs better.
100% infill for maximum strength?
It can even be worse: it accumulates internal stress and takes ages. 40-50% with more perimeters performs better.
Keep reading
Want to go deeper? We have a full article about this on the blog.
What if it isn't worth your time?
Sometimes the part is more urgent than the learning curve. We're a workshop in Viladecavalls: send us the file and we'll print it with the right material and settings.
Still not working?
Tell Marco which printer and material you use and he'll tell you what to change.
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