3D Printing Infill Explained: How Much Do You Really Need?

Infill is the internal structure inside a 3D print — the lattice that fills the space between the outer walls. It is one of the biggest levers you have over a part's strength, weight, print time and cost. Yet most people either leave it at the default or crank it far higher than they need. Here is how to pick the right setting, material by material and object by object.

What Infill Percentage Means

Infill is expressed as a percentage of solid material inside the shell. At 0% the part is hollow (aside from its outer walls); at 100% it is completely solid. Most functional prints land somewhere between 15% and 40% — enough to support the walls and resist load without wasting material or time. The slicer calculates this after the walls and top/bottom layers are placed, so infill only fills what's left of the interior volume — a thick-walled small part may end up mostly solid even at a "low" infill setting, simply because little interior volume remains once the walls are subtracted.

How Much Do You Actually Need?

• 0–10% — display models, figurines and prototypes where strength does not matter. Light and fast.
• 15–25% — the sweet spot for most everyday and lightly loaded parts.
• 30–50% — functional parts that take real stress: brackets, mounts, tools.
• 50–100% — only for parts under heavy compression or where maximum durability is essential.

Strength does not scale linearly with infill. Going from 20% to 40% adds noticeable strength; going from 60% to 100% adds a lot of cost and time for diminishing returns. Past roughly 60%, you are mostly paying for material that does very little extra work.

Walls Matter More Than You Think

Here is the surprise: for many parts, adding wall perimeters gives more strength per gram than adding infill. The solid shell carries much of the load, while infill mainly stops the walls from flexing or collapsing inward. If a part feels weak, try three or four walls with moderate infill before reaching for 80%. A part with four walls and 25% infill is often both cheaper and stronger than one with two walls and 80% infill.

Infill Patterns

The pattern is the shape of the internal lattice, and slicers usually offer six or more choices. The common ones:

• Grid / lines — fast and fine for general use.
• Cubic — strong in all three axes, a solid all-round default for functional parts.
• Gyroid — strong in all directions and prints efficiently with minimal travel moves; a great default when you're not sure what pattern to pick.
• Honeycomb — strong and rigid, but slower to print because of the extra perimeter moves per cell.
• Triangles — good strength on parts that face sideways loads.
• Lightning — barely any material at all; it only supports the top surface from below. Excellent for pure display pieces where the interior is never seen or loaded.

For most jobs the pattern matters less than the percentage and wall count, so a sensible default like gyroid or cubic is fine unless you have a specific need.

How Infill Needs Change by Material

The right infill also depends on what you're printing in — the same percentage behaves differently across our material range:

• PLA and PETG — the two most common materials print reliably at any infill percentage, so the 15–25% sweet spot applies almost without exception.
• TPU — being flexible by nature, TPU parts (gaskets, grips, phone cases) rarely need infill above 15–20% even when load-bearing; the material itself absorbs impact rather than the lattice doing the work.
• Nylon and PA-CF — used for gears, brackets and load-bearing parts, these often justify 30–50% infill paired with extra walls, because the whole point of choosing an engineering material is mechanical performance.
• ASA outdoor parts — infill has little to do with weather resistance, but slightly higher infill (25–35%) adds impact resilience for parts left outdoors and handled roughly.

The Cost Connection

Because infill is material and material takes time to print, it directly affects your quote — see our full breakdown of 3D printing costs in Singapore for how the rest of the price is built. As a rough illustration: on a part where the interior would otherwise be solid, dropping infill from 80% to 20% can cut the internal material by roughly three-quarters, which typically shaves a similar proportion off both the print time and the material-cost line of your quote. Walls, top/bottom layers and the outer shape don't change, so the part looks identical — it's just lighter and cheaper for non-structural use. Time usually falls by slightly less than weight, since the printer still has to travel across each layer even where it's depositing less plastic. This is one of the easiest ways to print smarter without redesigning anything.

A Quick Reference by Object Type

Object type	Suggested infill	Pattern
Figurines, display models	0–10%	Grid or lightning
Keychains, phone stands	10–15%	Grid or gyroid
Organisers, enclosures	15–20%	Gyroid
Brackets, mounts, jigs	25–40%	Gyroid or honeycomb
Gears, structural parts	40%+	Honeycomb or triangles

Treat this as a starting point rather than a rule — the right number always depends on the specific load your part needs to survive.

A Simple Rule of Thumb

Start at 15–20% with three walls. Increase infill only if the part will carry load, and add walls before pushing infill very high. For decorative pieces, drop it lower to save money and print time.

Not sure what your part needs? Upload your model for an instant quote — we will suggest infill and wall settings to match how the part will be used.

Not sure which infill your part needs? Upload your file and we will flag anything that looks over- or under-built before it prints.