Infill Percentage to Print Weight

Infill percentage and print weight

Infill decides how much plastic sits inside the part. You can ballpark the weight with weight ≈ solid_weight · (1 − (1 − infill%) · hollow_ratio), where hollow_ratio is the slice of internal volume that lives between the perimeters. At 100% infill the part is fully solid, so weight and strength peak. 20% is what Cura ships with and it strikes a good balance. 15% is on the light side and fine for decorative work, while 0% leaves you a hollow shell. The pattern counts too, since gyroid and honeycomb hold up better per gram than plain linear or grid fills. Run the numbers on a 50 cm³ PLA model: at 20% it lands near 25 g against roughly 62 g solid, so you keep more than half your filament.

Applications

Stretch your filament on decorative parts and prototypes by dropping to 10–15%. Beef up functional parts such as gears, brackets, and tool holders past 50% with gyroid or cubic. Keep scale models and miniatures light at 10–15%. For toys and cosplay props, 20–25% balances weight nicely. Reach for cubic or gyroid when the load can come from any direction, and save lines or zigzag for the cases where stress runs along a single axis.

FAQ

Does more infill always mean stronger? Not really. Once you cross 40–50% the returns flatten out, and above that range your wall count does more for strength than the infill does.

Best infill for functional parts? Go gyroid or cubic at 30–50% with at least 4 perimeters. When the part sees high stress, add walls before you turn up the infill.

Why is my part heavier than the calculator says? Walls, the top and bottom layers, and any supports pile on another 10–30% past the infill volume. This estimate only covers the infill region.