If you’re new to 3D printing, you’ve probably seen a setting called infill inside your slicer.
You might see numbers like 10%, 15%, 20% or even 100% — but what does that actually mean?
Infill is simply the structure printed inside your model. Most 3D prints are not completely solid. Instead, the printer creates an outer shell and then builds a pattern inside it.
That internal structure is the infill.
Why Do We Use Infill?
Infill helps give your print strength without needing to fill the entire model with plastic.
Printing something completely solid would normally:
– Use much more filament
– Take much longer to print
– Make the model heavier
– Cost more to produce
For many everyday prints, there is simply no need for the inside to be completely solid.
What Does the Percentage Mean?
The infill percentage controls roughly how much of the inside of the model is filled.
For example:
0% infill means the model is mostly hollow inside.
10–15% infill gives you a lightweight internal structure and is often enough for decorative models.
20–30% infill is a good general-purpose range for many useful prints.
40–60% infill can be used when a part needs extra strength.
100% infill makes the inside completely solid, although it is rarely necessary.
One thing worth remembering is that increasing infill does not automatically make a print massively stronger.
Sometimes increasing the number of walls or perimeters can improve strength more effectively than simply increasing the infill percentage.
What Does Infill Look Like?
There are lots of different infill patterns available in modern slicers.
Some of the common ones include:
– Grid
– Lines
– Gyroid
– Honeycomb
– Cubic
Each pattern builds the internal structure slightly differently.
Gyroid is particularly popular because it provides strength in several directions while still printing efficiently.
For most beginner prints, though, you don’t need to worry too much about choosing the perfect pattern.
Your slicer’s default option will usually work perfectly well.
How Much Infill Should I Use?
There isn’t one correct answer because it depends on what you’re printing.
For a decorative model, figure or display item, around 10–15% can often be enough.
For everyday items, around 15–25% is a good starting point.
For brackets, tools or functional parts, you may want 25–40% or more, depending on how much force the part will need to handle.
For very strong parts, it’s also worth looking at wall thickness, print orientation and the material you’re using rather than simply setting the infill to 100%.
Does More Infill Mean a Better Print?
Not necessarily.
More infill means:
– More filament
– Longer printing times
– Heavier prints
– Higher printing costs
So using 80% infill when 15% would do the job is normally just wasting material and time.
The aim is to use enough infill for the job you’re asking the print to do.
A Simple Beginner Rule
If you’re unsure where to start, try around 15–20% infill.
For many normal PLA prints, that’s a perfectly sensible starting point.
If you’re printing something decorative, you may be able to go lower.
If you’re printing something that needs to carry weight or take knocks, you may want to increase it.
And remember — infill is only one part of making a strong print. Walls, layer direction, material and print orientation can all make a huge difference too.
Final Thoughts
Infill might look like a complicated slicer setting when you first start 3D printing, but it’s actually quite simple.
It allows you to create strong, lightweight prints without wasting huge amounts of filament filling the entire model.
So the next time your slicer asks you whether you want 10%, 20% or 50% infill, you’ll know exactly what that number is changing.
