Infill Pattern Matters as Much as Infill Percentage
In a hurry? Skip straight to the numbers.
Open the Infill Percentage Calculator →Two prints at the identical infill percentage can have meaningfully different real-world strength, because percentage only tells you how much material is inside - not how that material is geometrically arranged.
Percentage Is a Volume Number, Not a Strength Number
Infill percentage describes what fraction of the internal volume gets filled with plastic, but says nothing about the shape of the internal lattice doing the filling. A grid pattern, a honeycomb pattern, and a gyroid pattern at the exact same 20% infill use the same amount of material and take similar time, but distribute that material's load-bearing capability very differently depending on which direction force is applied.
Common Infill Patterns and Where Each Excels
| Pattern | Strength characteristic | Best suited for |
|---|---|---|
| Grid / Rectilinear | Strong along the two printed line directions, weaker diagonally | Fast general-purpose prints, non-critical parts |
| Honeycomb | Even strength distribution in the horizontal plane | Parts needing balanced X/Y strength |
| Gyroid | Near-uniform strength in all three dimensions, including Z | Functional parts, especially where load direction is unpredictable |
| Cubic / Cubic Subdivision | Distributes load across angled internal cube faces | Parts under compressive load from multiple angles |
| Concentric | Follows the part's outer contour | Flexible parts, TPU prints |
Why Gyroid Has Become the Default Recommendation
Gyroid infill's triply-periodic minimal surface geometry means there's no single weak plane running straight through the part in any one direction - unlike grid infill, which has genuinely weaker load paths along the diagonal between its two printed line directions. This is why gyroid has become the community and slicer-default recommendation for most functional prints: it doesn't require you to predict which direction a part will actually be stressed from in order to get reasonable strength, which grid and honeycomb patterns effectively do require for their theoretical strength advantage to apply.
The Research Finding Most People Miss: Diminishing Returns Beyond a Threshold
Mechanical testing of FDM parts has repeatedly found that strength gains from increasing infill percentage taper off substantially past roughly 50%, because at that point the shell (walls and top/bottom layers) is already carrying the majority of the structural load in typical parts, and additional interior infill is reinforcing a region that wasn't the weak point to begin with. This is a big part of why the "60-100%: high-strength parts" guideline on the calculator page is really an upper bound for genuinely load-bearing or watertight cases - for most "just needs to not snap" functional parts, switching to a stronger pattern at a moderate percentage (25-30% gyroid, for example) often outperforms a much higher percentage of a weaker pattern like grid, at a fraction of the material and time cost.
Putting This Into Your Slicer Settings
If a part failed under load at a "reasonable" infill percentage, check the pattern before assuming you simply need more material - switching from grid or lines to gyroid or cubic at the same percentage often closes the strength gap without adding print time or material cost at all.
Ready to Put This Into Practice?
Now that you understand how it works, plug in your own numbers and get an instant, accurate result.
Use the Infill Percentage Calculator Now →