What Is Infill In 3D Printing?

3D printing is not always the easiest thing to do, and this is mostly due to the fact that there is so much that you need to know to be able to do it successfully.

What Is Infill In 3D Printing

One aspect of 3D printing that you may have heard of is called infill.

In this article, we are going to explain to you exactly what infill is in 3D printing, so you can gain a better understanding of it. Hopefully, this will help you to expand on your 3D printing knowledge and skills. 

What Is Infill?

3D printing allows you to control two aspects of a part, which are the exterior walls and infill. The walls will form the outer bit of the part, and the infill is whatever is inside of this.

Although you will have a limited amount of control over the walls, you will have much more control over the infill, which plays a big part in the strength, weight, buoyancy, structure, and more.

When you are 3D printing, you will be able to define a specific number of parameters that will determine the type of infill that is used for a part.

You can set these parameters in a slicer program when a 3D model will be translated into G-code instructions. The two most important parts of these parameters are the infill density and the infill pattern.

We are going to take a look at infill in 3D printing below, before going through some of the basics that you need to know about it below.

3D Printing VS Traditional Manufacturing

When it comes to 3D printing, infill is very different from traditional manufacturing processing. We will use injection molding and subtractive manufacturing as examples for this.

Injection molding actually involves inserting a material into a mold to form a part. Due to the nature of this method, it is not possible to control internal structures. As a result of this, these parts are typically either solid or empty.

Subtractive manufacturing involves cutting material off from a larger piece of stock. Similarly to injection molding, infill cannot be adjusted, which is why the interior will be completely solid.

On the other hand, 3D printing will involve selective extrusion of material in almost any pattern. We are going to explore the different options for infill density and pattern below.


Infill density is something that can significantly affect the material consumption. If you didn’t already know, the infill density is the fullness of the inside of a part.

This is typically defined as a percentage somewhere between 0 and 100. 0% indicates a hollow part, whereas 100% would be a completely solid part.

This will affect the weight of a part, and the fuller the part is, the heavier it will be.

As well as the weight of the part, the print time, material consumption, and buoyancy can also be impacted by the infill density.

How To Determine The Right Percentage

How To Determine To Right Percentage

The majority of standard prints do not need to be really strong, and you can go ahead and use an infill density of between 15 and 50%. This density percentage will keep the print time long and conserve material. It also provides a decent amount of strength.

Functional prints will need to be stronger than this. This is why it is recommended to use a higher infill of more than 50%.

Although, you can go as high as 100% if you want to. The setting is higher, and this means that it will take longer for the print, but you will create a stronger part.

For small figures and models that are only ever going to be used for display purposes, you can use an infill density of between 0 to 15%.

This will result in a quick print that will not consume very much filament. It will create a lightweight end result that is not very strong.

Recommended Settings

Standard prints: 15-50%
Functional prints: 50-100%
Figurine and model prints: 0-15%
Flexible prints: 1-100%


There are some infill patterns that will offer strength in either 2 or 3 dimensions. Infill patterns are the structure and shape of the materials that are inside of a part.

They can range from simple lines to more complex geometric shapes, and they can affect the strength, weight, flexibility, and print time.

There are lots of different infill patterns that you can choose from, depending on the program that you are using. Some programs will have more patterns than others.

Just like the infill density, there are some patterns that are better than others for certain purposes.

Different infill patterns will have different attributes, like their complexity, efficiency, and the number of planes of connective strength.

How To Determine Which Pattern To Use

You will need to ensure that you choose a pattern that will suit the needs of your part. We will explain some of the most common options below.

Lines – The lines infill pattern contains lines that are printed in one direction. This pattern provides strength in two dimensions, and it is great for quick prints. This pattern doesn’t use very much material, and it is quite light.

Honeycomb – The honeycomb structure is great when it comes to visual appeal, and it is great for semi-fast prints that will require moderate strength. It shouldn’t use up too much material.

Grid – The grid infill pattern is very similar in appearance to the lines pattern, but it has two dimensional lines instead of one-directional lines.

There is also twice as much space between the lines. The grid pattern uses an average amount of material.

Triangles – The triangle pattern looks like overlapping triangular lines that go in 3 directions in the XY plane. It only provides strength in two dimensions, but it still works for making strong prints.

Tri-hexagon – This infill pattern contains various lines that go in three directions in the XY plane, which creates hexagonal patterns that have triangles in between them.

This pattern provides strength in two dimensions, and it is great for creating strong prints.

Mark Andrews
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