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Best infill percentage for 3D printing

Short answer: 10–15% for decorative prints, 15–25% for everyday items, 25–40% for functional parts, and 50–100% only for small parts that take heavy loads.

Recommended infill by use

Walls beat infill

Bending and impact loads are carried mostly by the outer skin, the same way an I-beam's flanges do the work. Adding two extra walls usually adds more strength per gram than doubling infill. Tests by the community consistently show strength rising slowly above ~40% infill while weight and time keep climbing linearly.

Which pattern is strongest?

Gyroid and cubic give similar strength in every direction and print reliably. Grid and lines are strong along their lines but weaker across them, and grid can cause nozzle collisions at crossings. Lightning infill only supports top surfaces — great for models, useless for strength.

Weight and cost

Infill changes weight less than people expect because the walls and top/bottom layers are solid. On a 20 mm cube with 1.2 mm walls, going from 20% to 100% infill only raises the weight from about 4.8 g to 9.9 g. Use the infill estimator to see the trade-off for your own model.

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