Print Settings
Infill Explained: Hollow, Strong, and Everything In Between
Why 3D prints aren’t always solid plastic — and how infill percentage changes strength, weight, and print time.
Updated August 8, 2026 · About 6 min read
Cut a 3D printed bracket in half and you might see a honeycomb, grid, or gyroid pattern inside — not a solid block of plastic. That inner structure is called infill, and it’s one of the biggest levers for strength, weight, and how long a print takes.
Understanding infill helps you buy (or design) parts that won’t fail — and won’t waste material on jobs that don’t need a tank-like interior.
Walls vs infill (the important distinction)
Think of a print like a cardboard box: the walls (perimeters) are the outer shell; infill is the packing material inside. For many everyday loads, thicker walls matter more than cramming the inside to 100%.
A part with 3–4 solid walls and 20% infill often outperforms a thin-walled part with 80% infill — especially for bending and impact on the outer surface.
What the percentages mean
0–10% — Light / hollow
Display pieces, large props, anything where weight and speed matter more than strength. Feels light; can flex or crush under load.
15–25% — Everyday sweet spot
Most organizers, stands, and general shop parts. Good balance of strength, time, and filament use. This is where a lot of commercial FDM prints land.
30–50% — Functional / durable
Mounts, clips, RC parts, brackets. Heavier and slower, but holds up better to real use — especially when paired with solid walls.
80–100% — Near-solid
Rare for large parts (slow and expensive). Used for tiny high-stress pieces or when you truly need maximum mass. Diminishing returns vs just adding walls.
Infill patterns (quick tour)
- Grid / lines — Simple, fast, common default
- Honeycomb / cubic — Strong in multiple directions
- Gyroid — Smooth, flexible strength; popular for functional parts
- Triangles — Stiff; good when you need rigidity
As a buyer you usually won’t pick the pattern — the shop will. What you care about is the result: does the part feel solid enough for how you’ll use it?
Print time and cost
Higher infill = more plastic + more nozzle travel = longer prints and higher cost. Doubling infill doesn’t always double strength, but it often doubles wait time on chunky parts. That’s why made-to-order shops tune infill to the product instead of printing everything solid.
What to ask when you order
- Will this part take load, vibration, or impact?
- Does weight matter (drone, RC, handheld tool)?
- Is it mostly decorative?
- Any heat or outdoor exposure? (Material choice + infill both matter — see our PLA vs PETG guide.)
Tell us the use case and we’ll set walls and infill accordingly — that’s part of printing it right the first time.
FAQ
Is 100% infill always stronger?
Not always in practice. Extra walls and smart orientation often beat a high-infill, thin-shell print. Solid is useful for small high-stress bits — not every organizer.
Why can two identical-looking prints feel different?
Same exterior, different walls/infill inside. That’s normal — and intentional when one SKU is display-grade and another is functional.
Can I request denser infill?
Often yes on custom orders. Expect a bit more cost and lead time for larger parts.
Need a stronger print?
Browse the shop or contact us with your use case — we’ll dial in walls, infill, and material.