A simple desk holder needs only 15% infill, while a bracket meant to hold several kilograms already needs 50-70%. Many beginners print everything with PLA at a flat 20%, because that's what the slicer's default profile suggests - so they either waste filament on decorative prints or end up with a part that breaks exactly where strength mattered.
This guide shows how to match infill percentage to a specific use case, which pattern to pick, and how infill affects print time and material use. Instead of guessing, you get concrete numbers you can plug straight into Cura, PrusaSlicer, or Bambu Studio.
Starting infill settings - table
| Parameter | Value | Comment |
|---|---|---|
| Decorative infill | 0-15% | Display models and prototypes with no load |
| Light functional infill | 15-25% | Holders, enclosures, parts without major forces |
| Medium infill | 25-40% | Parts exposed to moderate stress |
| Structural infill | 50-70% | Brackets, hinges, mechanical parts |
| Maximum infill | 80-100% | Rarely needed, mostly small parts under heavy point loads |
| Default infill pattern | Grid or gyroid | A good balance between speed and strength |
| Pattern for maximum strength | Gyroid or honeycomb | Strength that's similar in every direction |
| Number of perimeters | 3-4 | Often matters more for strength than infill itself |
| Top/bottom solid layers | 4-6 | Prevents discoloration and pillowing over the infill |
| Gyroid angle | 0 degrees | Default value, usually no need to change it |
You'll find print temperatures for the specific material you're setting infill for in our temperature table.
Why infill percentage matters
Infill determines stiffness and resistance to bending and compression, but the relationship isn't linear. Up to around 40-50%, every extra percent noticeably improves strength; beyond that threshold the gain slows down, while filament use and print time keep climbing at the same rate. That's why printing at 100% rarely makes sense outside a few exceptions.
Infill never works in isolation from the rest of your settings. Just like with first layer settings, one neglected parameter can undo a well-chosen infill percentage - perimeters that are too thin, or too few solid top layers, mean that even 60% infill won't save a weak point in the structure.
It's also worth remembering that infill usually accounts for a smaller share of a print's volume than it seems - in a typical mid-sized part, the perimeters and solid layers generate most of the mass, not the core itself. That's why jumping from 15% to 25% usually adds a modest amount to the print's weight, not a dramatic one.
How much infill for different uses
Decorative models and prototypes
Figurines, display pieces, or prototypes printed to check dimensions don't need to carry any load. 0-15% infill is enough - mainly so the model doesn't sag under the weight of the top layers. Surface quality matters most here, so it's better to spend the time you save on slower, cleaner outer walls than on higher infill.
Everyday functional parts
Cable holders, organizers, electronics enclosures, or tool holders are typical 15-25% applications. That's the range most home and office prints fall into - stiff enough that the part won't deform, without wasting filament or time.
Structural and mechanical parts
Brackets under load, hinges, mounting parts, or components under stress need 50-70% infill, and even more under heavy point loads. Tough PLA works well for this kind of print, since its higher impact resistance handles dynamic loads better than standard PLA, regardless of the infill percentage.
Infill pattern and strength
Grid and lines (rectilinear). The fastest patterns to print, but also the weakest - rectilinear achieves roughly only about 70% of gyroid's strength at the same density, and its strength depends heavily on load direction.
Gyroid. A continuous, wavy structure that distributes stress almost evenly in every direction. It holds up well in shear even at low density, which is why it's the default choice in most modern slicer profiles. That comes at the cost of roughly 5-10% longer print time compared to straight lines.
Honeycomb. The strongest of the common patterns - it can carry up to 10-15% more force than gyroid at the same density, especially under compression and shear. It's noticeably slower to print, though, about 20-30% slower than gyroid, and works best where every bit of strength matters more than time.
Cubic and triangles. Cubic gives equal strength along the X, Y, and Z axes, though it's slightly weaker than gyroid in any single direction. The triangular pattern performs well along two of the three axes and can be a good compromise when the load direction is predictable.
Infill and material
PLA and PETG respond to infill in a similar way, but PETG's higher flexibility lets it handle lower infill better in spots exposed to impact - where PLA at 15% would crack, PETG tends to flex instead. ABS and ASA, due to their tendency to shrink, generally handle moderate infill in the 20-35% range better than very high infill, which increases internal stress and the risk of cracking while cooling.
TPU and flexible materials
With flexible filaments such as TPU 98A, the relationship flips compared to rigid materials. Lower infill, around 15-25%, preserves flexibility and cushioning, while high infill stiffens the print and partly defeats the point of using a flexible material. If softness matters - for example in insoles or shock-absorbing holders - stay near the lower end.
Variable infill and local reinforcement
You don't always need to raise infill across the whole model to reinforce one critical spot. Most modern slicers let you apply a modifier mesh to just a fragment of the geometry - a screw hole or a hinge eyelet, for example - and set much higher infill there without changing the rest of the model. This saves time and filament in places where extra density wouldn't add anything to overall strength anyway.
Adaptive infill and lightning infill
Some slicers offer adaptive infill, which automatically densifies the structure closer to the outer walls and thins it out deeper inside the model, where stress is usually lower. Lightning infill goes a step further - it builds only thin ribs supporting the top layers, which can cut print time by as much as 30-50% compared to gyroid at similar surface quality. It mainly works well on low-load models, though, since it doesn't provide uniform strength throughout the part's volume.
Infill, print time, and filament use
Going from 15% to 50% infill on a typical mid-sized part can extend print time by tens of percent and increase filament use by a similar amount - though rarely in a simple 1:1 ratio, since perimeters and solid layers stay unchanged. Before setting high infill "just in case," it's worth asking whether the part actually carries a load or just looks solid. In many cases, adding one or two extra perimeters is a better fix than raising infill - it costs less time and often adds more strength.
Settings for popular setups
| Setup | Recommended infill and speed | Comment |
|---|---|---|
| Bowden | 15-30%, infill speed 60-80 mm/s | Longer retraction path, don't push speed too far with dense patterns |
| Direct drive | 15-40%, infill speed 80-120 mm/s | Shorter retraction allows higher speeds without losing quality |
| Enclosed CoreXY | 20-50%, infill speed 150-300 mm/s | A stiff frame keeps quality high even at high density |
| AMS / CFS (multi-material) | 20-40%, gyroid pattern | Gyroid makes for smoother color transitions with no visible gaps |
Common mistakes
Setting 100% "just to be safe." This is the slowest and most expensive way to print, and strength gains grow disproportionately little above 70%.
Ignoring perimeter count. Two extra perimeters often add more stiffness than doubling the infill.
Too little infill under large flat surfaces. Without proper support, top layers start to sag, which shows up as pillowing on the print's surface.
Using the same pattern for everything. Rectilinear on a mechanical part wastes strength, and gyroid on a simple decoration wastes time.
Skipping a real load test. Settings found online are a starting point, not a guarantee - if a part will carry a specific load, print a sample and actually test it before committing to a production run.
Changing infill without changing speed. Dense patterns at too high a speed can hurt outer wall quality, because the printer can't keep up with cooling and positioning.
Ignoring the material when choosing infill. What works for PLA won't necessarily work for TPU or ABS - each material responds differently to core density.
Frequently asked questions
What infill should I use by default if I don't know what the print is for?
A safe starting point is 20% infill with a gyroid pattern - a value that works well for most home and office applications without adding too much print time.
Does 100% infill make a print as strong as an injection-molded part?
Not quite - even at 100% infill, an FDM print still has a layered structure and bond lines that limit its strength compared to a solid injection-molded part of the same material.
Does higher infill always mean higher strength?
Not always - past a certain point, usually 50-70%, strength gains clearly slow down, and real-world strength is more often decided by perimeter count and layer thickness than by pushing core density even higher.
Which infill pattern works best for parts loaded from multiple directions?
Gyroid, thanks to its nearly uniform strength distribution in every direction, is a good default choice for parts that may be loaded from different sides.
Does low infill save a lot of filament?
Yes, though the savings are smaller than you might expect, since perimeters and top/bottom solid layers stay unchanged regardless of the core infill percentage.
Summary
Infill percentage is worth matching to the specific use case rather than setting once and forgetting - 15% for decoration, 20-25% for everyday objects, and 50-70% where real mechanical strength matters. Infill pattern and perimeter count affect the outcome just as much as density itself, so changing only one of these parameters rarely solves a strength problem on its own.
If you're looking for a material that handles higher infill and real loads well, check out our technical filaments - you'll find materials matched to specific structural applications.