3D printing & CAD · Beginner

Infill

The hidden pattern a printer builds inside a part instead of solid plastic

What is infill in 3D printing?

Infill is the internal structure a 3D printer builds inside a part, instead of printing it solid. You set it as a percentage and a pattern, such as grid or gyroid. Less infill saves time and material; more makes the part heavier and stronger.

Think of it like this

Like the honeycomb inside a lightweight door: the outside looks solid, but a hidden pattern gives strength without the weight.

Where it fits in a 3D project

  1. Create
  2. Surface
  3. Rig
  4. Animate
  5. Render
  6. Export

Export: Saving and sharing the result: file formats, engines and printing.

How infill works

  1. 01The slicer plans solid outer walls and top and bottom layers.
  2. 02It fills the space inside with a pattern at your chosen density.
  3. 03Denser infill or stronger patterns add strength, time and material.
  4. 04Top layers bridge over the infill to close the surface.

Infill vs wall thickness

PropertyInfillWall thickness
What it isA pattern inside the partSolid lines forming the outer shell
Effect on strengthModerateOften larger
Material costSpread through the whole volumeOnly at the surface

For stronger parts, add walls before raising infill; an extra wall often adds more strength for the same plastic.

Where infill is used

  • Light display models at low density
  • Brackets and load-bearing parts at higher density
  • Flexible prints, where the pattern controls the squish

Beginner tip

Low infill suits most display prints, so start there. Go higher only for parts that take load, and add an extra wall or two first, since walls carry much of the strength.

Terms related to infill

Infill FAQ

What infill percentage should I use?
A common starting point is around 15 to 20 percent for display models and 30 to 50 percent for functional parts. Solid 100 percent infill is rarely needed and uses far more time and material.
What is the best infill pattern for strength?
Gyroid and cubic are popular all-round choices because they are strong in every direction. Grid and lines print fast but are weaker in some directions. For most beginners, gyroid is a safe default.
Does more infill make a print stronger?
Yes, up to a point, but the gains shrink as density rises. Extra walls or thicker top and bottom layers often strengthen a part more for the same added plastic.

Updated October 29, 2026 · Browse all 3D terms