Guide
3D Printing Infill: Strength, Weight, and Cost
Infill is the pattern printed inside a part. Most 3D prints are not solid plastic. They have a shell on the outside and a lattice inside. That inside lattice is the infill. You set it as a percentage. Zero percent is hollow. One hundred percent is solid. Infill controls how strong, heavy, and costly a part is. Most parts do well between 15 and 50 percent.
What infill actually is
Picture the inside of a printed part. It is rarely solid. Instead it holds a grid or honeycomb of plastic with gaps.
That inner grid is the infill. The walls you see on the outside are separate. They are called the shell or perimeters.
You pick an infill percentage. Higher percent means more plastic inside and fewer gaps. Lower percent means more empty space.
Common infill percentages
You do not need to memorize much. A few common settings cover most parts.
Fifteen to 20 percent works for models, toys, and light-duty parts. It is the everyday default. Forty to 50 percent suits parts that take real stress. Seventy-five to 100 percent is for parts that must be very strong or stiff.
Above 50 percent, you get less extra strength for each bit of added plastic. That is why very few parts need to be fully solid.
How infill affects strength, weight, and cost
More infill makes a part stronger and stiffer. It also makes the part heavier and more expensive. Every extra percent adds plastic and print time.
The gain is not steady. Going from 15 to 40 percent adds a lot of strength. Going from 60 to 100 percent adds much less for a lot more plastic.
Wall thickness matters too. Often, adding one more shell wall makes a part stronger than raising infill. Thicker walls carry load better than a dense center.
What we pick and why
For most parts, we aim for a smart balance. We want the part strong enough for its job without wasting plastic.
A common target is 15 to 25 percent for display and light-use parts. We go higher for functional parts that carry load or take impact.
The pattern also matters. Grid and honeycomb patterns give good strength for the plastic used. We set sensible defaults so you do not have to.
Choosing infill for your own part
Ask one question first. What job does the part do? A desk model can be light. A bracket that holds weight needs more.
If you are not sure, start in the middle. Around 20 percent is a safe base for many parts. Raise it only if the part must take real force.
You do not have to solve this alone. Upload your file and we handle sensible settings. For PA-CF or TPU, we send a fast human quote.
Quick takeaways
- Infill is the lattice printed inside a part, set as a percentage.
- Most parts do well between 15 and 50 percent.
- More infill means more strength, more weight, and more cost.
- Above 50 percent, you gain little strength for a lot more plastic.
- Thicker walls often add more strength than higher infill.
Have a part to print? Get an instant price.
Instant QuoteCommon questions
- What is a good infill percentage?
- For models and light-use parts, 15 to 20 percent is fine. For parts that carry load, use 40 to 50 percent. Very few parts need 100 percent.
- Does more infill make a part stronger?
- Yes, but the gain slows down. Going from 15 to 40 percent adds a lot of strength. Going from 60 to 100 percent adds much less.
- Does infill affect the price?
- Yes. More infill uses more plastic and more print time. Both raise the cost. Lower infill can save you money.
- Is 100 percent infill ever needed?
- Rarely. It makes a part very heavy and costly. Most strong parts do well at 50 to 75 percent with thicker walls.
- Do I have to set infill myself?
- No. We pick sensible settings for your part. Upload your STL for an instant price on PLA and PETG.